Pre-Action and Deluge Sprinkler Systems

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−---

−title: Pre-Action and Deluge Sprinkler Systems

−category: Fire Protection

−toc_depth: 3

−description: >

− When to use: Water-based fire suppression systems in which the distribution piping is normally dry and water is admitted only when a separate fire detection system operates the pre-action or deluge valve. Covers single-interlock pre-action systems (water admitted on detection alone) and double-interlock pre-action systems (water admitted only on coincident detection and loss of supervisory air), both of which use closed (automatic) sprinklers and are selected for water-sensitive, high-value, or freezer occupancies where an accidental discharge would cause unacceptable damage — data centers and equipment rooms, telecommunications and electrical rooms, archives, museums, rare-book and records storage, freezer and refrigerated warehouses, and clean rooms. Also covers deluge systems, which use open (orificed) sprinklers or spray nozzles on dry piping so that water discharges simultaneously from every device the instant the deluge valve trips, for high-hazard occupancies where rapid total-area application is required — transformer and oil-filled equipment rooms, aircraft hangars, flammable and combustible liquid handling, chemical process areas, conveyors, and similar exposures. Includes the releasing detection and control system, the pre-action or deluge valve and its trim, the supervisory air or nitrogen supply, the closed- or open-head distribution piping, low-point drainage, the water supply and fire pump interface, and acceptance testing including the valve trip test and water delivery time verification.

− Not intended for: Wet-pipe systems in conditioned occupied spaces (see [[sync/wet-pipe-fire-sprinkler-systems]]); conventional dry-pipe systems that trip on sprinkler operation alone without a separate detection event (see [[sync/dry-pipe-fire-sprinkler-systems]]); gaseous clean-agent total-flooding suppression for the same water-sensitive rooms where no water is acceptable at all (see [[sync/clean-agent-fire-suppression]]); the fire detection and alarm system beyond the releasing circuits, initiating devices, and releasing control unit serving these valves (see [[sync/fire-alarm-systems]]); fire pump installations (see [[sync/fire-pumps]]); foam-water and foam-deluge systems requiring foam concentrate proportioning (which add NFPA 11 and NFPA 16 requirements beyond this standard); water-mist systems; underground fire service mains; or standpipe and hose systems.

−---

−

−# Scope {toc}

−

−## This standard covers the design documentation requirements, materials, installation, testing, and acceptance criteria for pre-action and deluge fire sprinkler systems. {note}

−## These systems share a defining characteristic that distinguishes them from both wet-pipe and conventional dry-pipe systems: the distribution piping is normally dry, and water is admitted to the piping by a pre-action valve or deluge valve that is operated by a separate, independent fire detection system rather than by the opening of a sprinkler alone. {note}

−

−## The detection system, arranged and listed for releasing service, is the primary actuating event, and the releasing control unit, not the sprinkler, decides when water enters the pipe. {note}

−

−## The scope extends from the supply-side connection at the pre-action or deluge valve assembly — including the valve trim, the priming and pilot lines, the supervisory air or nitrogen supply, the solenoid and pneumatic actuators, the manual release, the intermediate chamber drain, and the main drain — through all above-ground supply mains, cross mains, branch lines, and end connections to the individual sprinklers or open nozzles.

−

−## The releasing detection and control system, low-point auxiliary drains, valve supervisory devices, the waterflow alarm, the fire department connection, system pitch and drainage, hangers and seismic bracing, and the air or nitrogen supply are included.

−

−## The hydraulic design, the system volume, and the detection-to-discharge response time govern all of these components together as an integrated suppression and detection system. {note}

−

−## Pre-action and deluge systems installed under this standard shall comply with NFPA 13, NFPA 72 (for the detection and releasing functions), the International Fire Code (IFC), and the International Building Code (IBC) as adopted locally.

−

−## Where local amendments modify NFPA 13 or NFPA 72 requirements, the local amendment shall govern unless it is less stringent than the base standard, in which case the base standard governs.

−

−## The Contractor and the designer shall confirm the editions of NFPA 13 and NFPA 72 adopted in the jurisdiction prior to beginning design work.

−

−## Successive editions have changed system volume limits, water delivery time rules, design-area penalties for double-interlock systems, releasing circuit requirements, and corrosion protection that affect both design and material procurement. {note}

−

−## This standard does not govern foam-water deluge or foam-deluge systems that require foam concentrate, proportioning equipment, and the additional design rules of NFPA 11 and NFPA 16.

−

−## This standard does not govern occupancy-specific or commodity-specific systems designed under the storage chapters of NFPA 13, which require specialized density, area, in-rack sprinkler, and water-delivery analysis beyond the scope of this document.

−

−## The Engineer of Record shall confirm whether foam or storage-specific rules apply to any portion of the project before releasing this standard for use.

−

−# Differentiation from Wet-Pipe and Dry-Pipe Systems {toc}

−

−## Pre-action and deluge systems are the most mechanically and electrically complex water-based suppression systems; they introduce a separate detection system, a releasing control unit, electrical releasing circuits, and a valve actuation chain, each of which is an additional component that shall be designed, installed, supervised, tested, and maintained.

−

−```datasheet

−label: System Type Selected

−type: select

−drawing_ref: true

−options:

− - "Single-interlock pre-action (water-sensitive, high-value, closed heads)"

− - "Double-interlock pre-action (freezer / refrigerated, closed heads)"

− - "Deluge (high-hazard, open heads, total-area discharge)"

−default: "Single-interlock pre-action (water-sensitive, high-value, closed heads)"

−```

−

−```datasheet

−label: Reason for Pre-Action or Deluge Selection

−type: select

−drawing_ref: true

−options:

− - "Data center or computer equipment room"

− - "Telecommunications or electrical equipment room"

− - "Archive, library, museum, or records storage"

− - "Freezer or refrigerated warehouse (double-interlock)"

− - "Clean room or laboratory"

− - "Transformer or oil-filled equipment room (deluge)"

− - "Aircraft hangar (deluge — see also NFPA 409)"

− - "Flammable / combustible liquid or chemical process (deluge)"

− - "Combustible conveyor (deluge)"

− - "Other — see basis of design"

−default: "Data center or computer equipment room"

−```

−

−## A pre-action or deluge system shall not be substituted for a wet-pipe or dry-pipe system where the simpler system is appropriate.

−

−## The justification for the added complexity of a pre-action or deluge system shall be documented by the Engineer of Record in the basis-of-design narrative.

−

−## A single-interlock or double-interlock pre-action system is selected when the protected space is water-sensitive or high-value and an accidental discharge from a physically damaged sprinkler or fitting would cause unacceptable loss. {note}

−

−## The pre-action interlock keeps water out of the piping until a fire is independently confirmed by detection, so a broken sprinkler in an empty room leaks air, not water. {note}

−

−## A double-interlock pre-action system is the standard choice for freezer and refrigerated warehouses, where a single-interlock system would still admit water on detection alone and where the operators want both a detection event and a sprinkler event to coincide before water enters the pipe. {note}

−

−## A deluge system is selected when the hazard is severe enough that water shall be applied simultaneously over an entire area the instant a fire is detected, faster than sequential sprinkler operation can achieve.

−

−## Deluge systems use open sprinklers or spray nozzles with no thermal element, so every device on the system discharges together when the deluge valve trips. {note}

−

−## Representative deluge applications are transformer and oil-filled equipment rooms, aircraft hangars, flammable and combustible liquid handling and process areas, chemical plants, and combustible conveyors where a fire can spread along the line faster than individual heads would open. {note}

−

−# Referenced Standards {toc}

−

−## Materials, design, installation, and testing shall comply with the current adopted editions of the following standards.

−

−| Standard | Title |

−|----------|-------|

−| NFPA 13 | Standard for the Installation of Sprinkler Systems |

−| NFPA 20 | Standard for the Installation of Stationary Pumps for Fire Protection |

−| NFPA 24 | Standard for the Installation of Private Fire Service Mains and Their Appurtenances |

−| NFPA 25 | Standard for the Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems |

−| NFPA 70 | National Electrical Code |

−| NFPA 72 | National Fire Alarm and Signaling Code |

−| NFPA 291 | Recommended Practice for Fire Flow Testing and Marking of Hydrants |

−| NFPA 409 | Standard on Aircraft Hangars |

−| IBC | International Building Code |

−| IFC | International Fire Code |

−| ASTM A53 | Standard Specification for Pipe, Steel, Black and Hot-Dipped, Zinc-Coated, Welded and Seamless |

−| ASTM A135 | Standard Specification for Electric-Resistance-Welded Steel Pipe |

−| ASTM A234 | Standard Specification for Piping Fittings of Wrought Carbon Steel and Alloy Steel for Moderate and High Temperature Service |

−| ASTM A795 | Standard Specification for Black and Hot-Dipped Zinc-Coated (Galvanized) Welded and Seamless Steel Pipe for Fire Protection Use |

−| ASME B16.5 | Pipe Flanges and Flanged Fittings |

−| ASME B16.9 | Factory-Made Wrought Buttwelding Fittings |

−| ASME B16.11 | Forged Fittings, Socket-Welding and Threaded |

−| UL 199 | Automatic Sprinklers for Fire Protection Service |

−| UL 260 | Dry Pipe Valves for Fire Protection Service |

−| UL 262 | Gate Valves for Fire Protection Service |

−| UL 312 | Check Valves for Fire Protection Service |

−| UL 753 | Alarm Accessories for Automatic Water-Supply Control Valves for Fire Protection Service |

−| UL 864 | Control Units and Accessories for Fire Alarm Systems |

−| UL 1091 | Butterfly Valves for Fire Protection Service |

−| UL 2017 | General-Purpose Signaling Devices and Systems |

−| FM Global 1011-1014 | Approval Standard for Deluge and Pre-Action Valves and Their Trim |

−| FM Global 2024 | Approval Standard for Air Maintenance Devices for Sprinkler Systems |

−| FM Global DS 2-0 | Installation Guidelines for Automatic Sprinklers |

−| FM Global DS 2-8N | Corrosion in Automatic Sprinkler Systems |

−| ANSI/AWWA C606 | Grooved and Shouldered Joints |

−

−## Where standards conflict, the more stringent requirement shall govern unless directed otherwise by the Engineer of Record in writing.

−

−# Submittals {toc}

−

−## Action Submittals {toc}

−

−### The Contractor shall submit the following for the Engineer of Record's review and the Authority Having Jurisdiction's approval prior to procurement and installation.

−### The submittal package shall demonstrate compliance on two fronts at once: the hydraulic and water-delivery performance of the water side under NFPA 13, and the detection, releasing, and sequence-of-operation performance of the detection side under NFPA 72.

−### The two sides are coordinated through a single document — the sequence of operations (releasing matrix) — that the AHJ uses to confirm that the right detection event causes the right valve to release at the right time. {note}

−

−### The following items shall be submitted as a coordinated package:

−

−- Working drawings for the sprinkler system complying with NFPA 13 Chapter 28, including floor plans showing pipe routing, pipe sizes, sprinkler or open-nozzle types and locations, elevations, riser diagrams, the hydraulic reference node diagram, and pitch and drainage details with all auxiliary drain locations

−- A releasing matrix (sequence of operations) identifying each initiating device or zone, the cross-zoned logic, the releasing output to each pre-action or deluge valve, the alarm and supervisory outputs, and any interlocks to HVAC, dampers, door release, or equipment shutdown

−- Detection and releasing system drawings complying with NFPA 72, including detector layout and spacing, the releasing control unit, releasing circuit class and survivability, manual release station locations, end-of-line supervision, and battery / secondary power calculations

−- Hydraulic calculations performed by the pipe-sizing method, demonstrating that the system meets the design density and area for each hazard area, with the demand plotted against the supply curve including hose stream allowances and the required safety margin demonstrated at the design point

−- A calculated system volume and, where required by NFPA 13, a water delivery time calculation demonstrating that water reaches the inspector's test connection within the applicable time limit (double-interlock pre-action and deluge systems are treated as dry-pipe systems for water delivery purposes)

−- Trip-time calculations for the pre-action or deluge valve demonstrating that the valve operates and water is delivered within the time assumed in the sequence of operations

−- Product data and listings for the pre-action or deluge valve and trim, the releasing solenoid, the releasing control unit, all detectors, the air maintenance device or nitrogen generator (pre-action), all sprinklers or open nozzles, valve supervisory switches, the waterflow alarm device, the fire department connection, and hangers

−- Manufacturer's installation instructions for the valve, the releasing control unit, and the detection devices, including any limitations on application, system arrangement, supervisory air tolerance, or releasing circuit compatibility

−- A pipe pitch and drainage plan showing all low points, auxiliary drains, the main drain, and elevation callouts confirming compliance with the minimum pitch required by NFPA 13

−- Seismic bracing calculations, where required by the project's Seismic Design Category

−

−```datasheet

−label: Action Submittals Required

−type: checkbox

−options:

− - "Working drawings per NFPA 13 Chapter 28"

− - "Releasing matrix / sequence of operations"

− - "Detection and releasing drawings per NFPA 72"

− - "Hydraulic calculations"

− - "System volume and water delivery time calculation"

− - "Valve trip-time calculations"

− - "Product data and listings for valve, releasing panel, detectors"

− - "Manufacturer installation instructions"

− - "Pipe pitch and drainage plan with auxiliary drain locations"

− - "Battery / secondary power calculations"

− - "Seismic bracing calculations (if required)"

−default: "Working drawings per NFPA 13 Chapter 28"

−```

−

−### No work shall proceed on any portion of the pre-action or deluge system until the corresponding submittals are reviewed, returned, and any required approval from the AHJ is in hand.

−

−### Working drawings shall be prepared by or under the supervision of a person with qualifications acceptable to the AHJ.

−

−### The Contractor shall confirm designer qualification requirements for both the water-side and detection-side disciplines before assigning the design work.

−

−### The water-side layout shall be prepared by a licensed fire protection engineer or a NICET-certified sprinkler designer, and the detection and releasing design by a person holding NICET certification in fire alarm systems or a licensed engineer, as required by the jurisdiction.

−

−## Closeout Submittals {toc}

−

−### The following shall be submitted at substantial completion before the system is accepted:

−

−- Contractor's Material and Test Certificate for Aboveground Piping (NFPA 13 Figure 29.1.1), signed by the installing contractor, certifying materials, joint types, flushing, hydrostatic test, air pressure test (pre-action), valve trip test, water delivery time, and alarm and supervisory device operation

−- Record of Completion and inspection/test forms for the detection and releasing system per NFPA 72, signed by the fire alarm contractor

−- As-built drawings reflecting field changes from the reviewed working drawings, including the as-built releasing matrix

−- Operation and maintenance manual including valve impairment and reset procedures, releasing panel programming record, detector sensitivity records, air or nitrogen supply maintenance, seasonal drainage procedures, and NFPA 25 and NFPA 72 inspection intervals

−- Warranty documentation for all components carrying a manufacturer warranty

−- Hydraulic and water delivery design information signs confirming the installed signs match the design calculations

−- Air leakage test record for pre-action systems demonstrating compliance with the NFPA 13 air-leakage limit

−

−```datasheet

−label: Closeout Submittals Required

−type: checkbox

−options:

− - "Contractor's Material and Test Certificate for Aboveground Piping"

− - "NFPA 72 Record of Completion for detection / releasing"

− - "Valve trip test record with water delivery time"

− - "Air leakage test record (pre-action)"

− - "As-built drawings and as-built releasing matrix"

− - "Operation and maintenance manual with panel programming record"

− - "Manufacturer warranty documentation"

− - "Hydraulic and water delivery design information signs"

−default: "Contractor's Material and Test Certificate for Aboveground Piping"

−```

−

−### The Contractor shall submit the closeout submittal items listed above at substantial completion before the system is accepted.

−

−# Quality Assurance {toc}

−

−## Installer Qualifications {toc}

−

−### Because these systems combine a water-based system and a detection/releasing system, the installing entity shall hold, or shall engage subcontractors holding, both a fire protection (sprinkler) contractor's license and a fire alarm contractor's license as required locally.

−

−### Pre-action and deluge system installation shall be performed by a licensed fire protection contractor as required by the state and local jurisdiction.

−

−### The individual preparing the sprinkler working drawings and hydraulic calculations shall hold qualifications acceptable to the AHJ.

−

−### Where state law requires NICET certification, the sprinkler designer shall hold NICET Level III or IV in water-based systems layout and the detection designer shall hold NICET certification in fire alarm systems, as applicable.

−

−### Where the Contractor's in-house staff lacks experience in system volume sizing, water delivery time analysis, releasing circuit design, cross-zoned detection logic, and integration of the valve actuation chain with the releasing control unit, the design shall be subcontracted to or peer-reviewed by qualified specialists.

−

−### The Contractor shall identify both the sprinkler design lead and the detection design lead on the working drawings.

−

−## Coordination with Other Trades {toc}

−

−### The sprinkler Contractor shall coordinate early and continuously with the fire alarm, mechanical, electrical, structural, and architectural trades.

−

−### The pre-action or deluge valve room or enclosure shall be in a heated space adjacent to the protected area.

−

−### The releasing control unit shall be provided with conditioned space, dedicated power, and secondary (battery) power.

−

−### The air compressor or nitrogen generator (pre-action) requires dedicated electrical service and possibly ventilation.

−

−### Auxiliary drains shall be accessible at every low point.

−

−### The releasing matrix shall be coordinated with HVAC shutdown, damper closure, and any equipment power-down required when the valve releases.

−

−### The location and structural capacity of the structure to which hangers and seismic braces attach shall be confirmed with the structural engineer before hanger installation.

−

−### Hanger design loads shall account for the water-filled pipe weight plus an allowance for residual water remaining after a release.

−

−## Listing and Approval {toc}

−

−### All sprinklers and open nozzles, pre-action and deluge valves, releasing solenoids, releasing control units, detection devices, air maintenance devices, nitrogen generators, valves, hangers, seismic brace assemblies, and alarm devices shall be listed by a Nationally Recognized Testing Laboratory (UL, FM, or another NRTL accepted by the AHJ) for the specific application and service conditions.

−

−### Sprinklers shall be listed to UL 199 and open nozzles to their applicable listing.

−

−### The releasing control unit shall be listed to UL 864 for releasing service; a general-purpose fire alarm control unit that is not specifically listed for releasing service shall not be used to operate a pre-action or deluge valve.

−

−### The releasing solenoid and the valve shall be listed together as a compatible combination, and mixing solenoid and valve from different manufacturers is not permitted unless the combination is independently listed.

−

−## FM Global Compliance {toc}

−

−### Where the building's property insurance carrier or the Owner requires FM Global compliance, all components shall be FM-approved in addition to UL-listed.

−

−```datasheet

−label: FM Global Compliance Required

−type: radio

−options:

− - "Not required"

− - "Required — FM-approved components throughout"

−default: "Not required"

−```

−

−### FM and UL listings are not identical, and cross-zoned detection arrangements accepted under one listing or jurisdiction may not be accepted under another. {note}

−

−### The Contractor shall confirm approval status for each product and each detection arrangement at procurement, not after installation.

−

−## Corrosion Protection {toc}

−

−### Internal corrosion is an aggressive problem in pre-action and deluge systems: residual water trapped at low points after testing or a release, combined with the oxygen in the supervisory air (pre-action) or the open atmosphere (deluge), drives microbiologically influenced corrosion (MIC) and oxygen pitting that can perforate the pipe wall over the service life. {note}

−

−### For pre-action systems the Contractor shall provide one of three corrosion-mitigation approaches: galvanized steel pipe throughout; nitrogen inerting using a listed nitrogen generator that displaces oxygen; or both, where the Owner's risk profile or insurance requirements warrant enhanced protection.

−

−```datasheet

−label: Corrosion Mitigation Approach

−type: radio

−options:

− - "Galvanized steel pipe throughout, air supervised (pre-action)"

− - "Black steel pipe, nitrogen inerted (pre-action)"

− - "Galvanized steel pipe, nitrogen inerted (pre-action, enhanced)"

− - "Galvanized steel pipe, complete drainage (deluge)"

−default: "Galvanized steel pipe throughout, air supervised (pre-action)"

−```

−

−### NFPA 13 recognizes nitrogen inerting as an alternative to galvanized pipe for corrosion control on supervised dry systems, and nitrogen is the default for long-life critical assets such as data centers and freezer warehouses. {note}

−

−### Deluge piping, being open to atmosphere, shall not be nitrogen-inerted; deluge piping shall be galvanized and shall be designed to drain completely after each release and test.

−

−# Environmental and Service Conditions {toc}

−

−## Temperature Range {toc}

−

−### The valve trim, priming water, pilot lines, and supply-side piping shall not be allowed to freeze.

−

−```datasheet

−label: Minimum Protected Space Temperature

−type: range

−unit: °F

−drawing_ref: true

−options:

− min: -40

− max: 100

− setpoints: [-40, -20, 0, 32, 40, 70, 100]

−default: 70

−```

−

−```datasheet

−label: Valve Room Minimum Temperature

−type: range

−unit: °F

−options:

− min: 40

− max: 70

− setpoints: [40, 50, 60, 70]

−default: 50

−```

−

−### The valve and its trim shall be installed in a heated enclosure or valve room maintained at not less than 40°F (4°C) at all times.

−

−### Where the protected space is a freezer or refrigerated room, the designer shall account for the temperature differential at the valve-room-to-cold-space boundary and shall provide insulation, heat trace, or vapor barriers as required to prevent moisture migration into the dry piping during defrost cycles.

−

−### A single-interlock system shall not be used in a freezer, because it admits water on detection alone, before any sprinkler opens, filling cold piping with water that will freeze.

−

−### The double interlock exists specifically so that water is not admitted to freezer piping until a sprinkler has also opened. {note}

−

−## Maximum Working Pressure {toc}

−

−### On a pre-action system the supervisory air pressure shall be maintained within the range specified by the valve manufacturer's listing; differential pre-action valves require the air pressure to be held above a manufacturer-specified value to keep the clapper seated, while low-differential and electrically operated valves hold by other means and use a lower supervisory pressure.

−

−```datasheet

−label: System Working Pressure

−type: range

−unit: psi

−drawing_ref: true

−options:

− min: 40

− max: 250

− setpoints: [40, 100, 125, 150, 175, 200, 250]

−default: 150

−```

−

−```datasheet

−label: Supervisory Air or Nitrogen Pressure (pre-action)

−type: range

−unit: psi

−options:

− min: 7

− max: 60

− setpoints: [7, 10, 15, 20, 25, 40, 60]

−default: 20

−```

−

−### The system working pressure shall not exceed 175 psi at the valve unless the system and components are rated for a higher pressure.

−

−### Where the water supply static pressure exceeds 175 psi, a listed pressure-reducing valve shall be provided.

−

−# Design Basis and Hazard Classification {toc}

−

−## Occupancy Hazard Classification {toc}

−

−### Hazard classification determines the design density, the design area, and therefore the flow and pressure demand on the water supply. {note}

−

−### The hazard classification shall be assigned by the designer based on the occupancy descriptions in NFPA 13 Chapter 5 and confirmed with the Owner and the AHJ before the hydraulic design is finalized.

−

−```datasheet

−label: Predominant Occupancy Hazard Classification

−type: select

−drawing_ref: true

−options:

− - "Light Hazard"

− - "Ordinary Hazard Group 1"

− - "Ordinary Hazard Group 2"

− - "Extra Hazard Group 1"

− - "Extra Hazard Group 2"

− - "Special hazard — deluge, engineered density"

−default: "Ordinary Hazard Group 1"

−```

−

−### Pre-action systems most commonly protect Light Hazard and Ordinary Hazard occupancies, while archives and records storage may be Light Hazard or may invoke the storage rules. {note}

−

−### Deluge systems are typically applied to Extra Hazard and special-hazard occupancies where the density is high and the design covers the entire deluge zone, not a calculated remote area. {note}

−

−## Design Density and Area {toc}

−

−### Design density and area shall be determined from NFPA 13 for the applicable hazard classification, with the system-type adjustment applied.

−### The adjustment is the single most important design-basis distinction among the three system types covered by this standard, and the designer shall apply it correctly.

−

−```datasheet

−label: Design Area Basis by System Type

−type: radio

−options:

− - "Single-interlock pre-action — wet-pipe design area (no 30% increase)"

− - "Double-interlock pre-action — wet-pipe area increased 30% (dry-pipe rule)"

− - "Deluge — entire zone area, all heads flowing simultaneously"

−default: "Single-interlock pre-action — wet-pipe design area (no 30% increase)"

−```

−

−```datasheet

−label: Design Density

−type: range

−unit: gpm/ft²

−drawing_ref: true

−options:

− min: 0.10

− max: 0.60

− setpoints: [0.10, 0.15, 0.20, 0.30, 0.40, 0.45, 0.60]

−default: 0.15

−```

−

−```datasheet

−label: Design Area (pre-action) or Deluge Zone Area

−type: range

−unit: ft²

−drawing_ref: true

−options:

− min: 1500

− max: 6500

− setpoints: [1500, 1950, 2600, 3250, 3900, 5200, 6500]

−default: 1950

−```

−

−### A single-interlock pre-action system admits water on detection alone, typically before the sprinklers open, so NFPA 13 does not apply the 30 percent design-area increase to it; it is treated, for area purposes, like a wet-pipe system at the same hazard classification.

−

−### NFPA 13 requires the design area for a double-interlock pre-action system to be increased by 30 percent over the wet-pipe area for the same hazard, without revising the density, exactly as for a dry-pipe system.

−

−### The 30 percent increase for a double-interlock pre-action system is mandatory and shall not be reduced by engineering judgment.

−

−### A deluge system discharges from every open device the instant the valve trips, so the design covers the entire area served by the deluge zone at the required density, with no remote area because all heads flow at once.

−

−### The water supply and fire pump shall be sized for simultaneous flow from every open device in the deluge zone, or in multiple zones where the design assumes more than one zone may operate together.

−

−## Hose Stream Allowance {toc}

−

−### The hose stream allowance is the same as for a wet-pipe system at the same hazard classification: 100 gpm for light hazard, 250 gpm for ordinary hazard, and 500 gpm for extra hazard. {note}

−

−### The hose stream allowance shall be specified to match the hazard classification of the sprinkler or deluge design.

−

−```datasheet

−label: Hose Stream Allowance

−type: select

−unit: gpm

−options:

− - "100 gpm (Light Hazard)"

− - "250 gpm (Ordinary Hazard)"

− - "500 gpm (Extra Hazard)"

−default: "250 gpm (Ordinary Hazard)"

−```

−

−### The hose stream demand shall be applied simultaneously with the sprinkler or deluge demand.

−

−## Water Supply Verification {toc}

−

−### Because deluge demand is large with all heads flowing, deluge systems frequently require a fire pump. {note}

−

−### Water supply data shall be obtained by a hydrant flow test conducted at or near the project site in accordance with NFPA 291, no more than 12 months prior to the date of submittal.

−

−```datasheet

−label: Water Supply Source

−type: select

−options:

− - "Public water main — flow test required"

− - "Dedicated fire water storage tank and pump"

− - "Combined public main and storage tank"

−default: "Public water main — flow test required"

−```

−

−### Static pressure, residual pressure, and pitot flow shall be recorded.

−

−```datasheet

−label: Static Pressure at Flow Test

−type: range

−unit: psi

−drawing_ref: true

−options:

− min: 20

− max: 150

− setpoints: [20, 40, 50, 60, 70, 80, 90, 100, 120, 150]

−default: 70

−```

−

−```datasheet

−label: Residual Pressure at Flow Test

−type: range

−unit: psi

−drawing_ref: true

−options:

− min: 10

− max: 130

− setpoints: [10, 20, 30, 40, 50, 60, 70, 80, 100, 130]

−default: 50

−```

−

−### The designer shall plot the supply curve and confirm that the system demand including hose stream falls below the supply curve with the safety margin required by NFPA 13.

−

−### Where the available supply does not meet the demand, a fire pump shall be provided per [[sync/fire-pumps]].

−

−# System Types {toc}

−

−## Single-Interlock Pre-Action {toc}

−

−### A single-interlock pre-action system uses closed (automatic) sprinklers on piping that is held under supervisory air or nitrogen, and it admits water to the piping on the operation of the detection system alone. {note}

−### When a detector operates, the releasing control unit energizes the release solenoid (or trips a pneumatic actuator), the pre-action valve opens, and water fills the piping up to the still-closed sprinklers; water then discharges only when a sprinkler subsequently opens from heat. {note}

−

−### The single interlock provides one layer of protection against accidental discharge: a physically broken sprinkler or fitting in a room with no fire releases supervisory air and signals a trouble condition, but it does not admit water, because no detector has operated.

−

−### Single-interlock systems are limited by NFPA 13 to no more than 1,000 automatic sprinklers controlled by any single pre-action valve.

−

−```datasheet

−label: Maximum Sprinklers per Pre-Action Valve

−type: range

−unit: heads

−options:

− min: 100

− max: 1000

− setpoints: [100, 250, 500, 750, 1000]

−default: 1000

−```

−

−### Because water arrives on detection before the sprinklers open, the single-interlock system does not take the 30 percent design-area penalty.

−

−## Double-Interlock Pre-Action {toc}

−

−### A double-interlock pre-action system also uses closed sprinklers on supervised dry piping, but it requires two coincident events before water is admitted: a detection event and a loss of supervisory air pressure caused by a sprinkler opening or by piping damage. {note}

−### Only when the releasing control unit sees both signals — typically a cross-zoned detection signal and a low-air signal — does it energize the release solenoid to open the valve. {note}

−

−### The double requirement makes the system suitable for freezers, because water is not admitted to the cold piping on a detector alone, so a false detector signal in an empty freezer does not fill the piping. {note}

−

−### A double-interlock system is treated as a dry-pipe system for water delivery time and for the 30 percent design-area increase.

−

−## Deluge {toc}

−

−### A deluge system uses open sprinklers or spray nozzles — there is no thermal element — on piping that is open to atmosphere downstream of the deluge valve. {note}

−### The deluge valve is held closed only by the pilot/priming arrangement, not by system pressure on the discharge side, and it is operated by the detection system through the releasing control unit. {note}

−### When the valve trips, water flows to every open device simultaneously and discharges over the entire protected zone at once. {note}

−

−### Deluge systems shall be used where the hazard demands immediate total-area application, such as transformer and oil-filled equipment, aircraft hangars, flammable liquid and chemical process areas, and combustible conveyors.

−

−### Because the piping is open, a deluge system is not air-supervised; instead the detection circuit, the valve actuation, and the open-nozzle layout shall be supervised and tested, and the piping shall be designed to drain completely after each operation.

−

−# Releasing Detection and Control {toc}

−

−## Releasing Control Unit {toc}

−

−### The releasing control unit monitors the initiating devices, executes the releasing logic defined in the sequence of operations, energizes or de-energizes the release solenoid depending on the listed arrangement, and transmits alarm, supervisory, and trouble signals to the building fire alarm system or supervising station. {note}

−

−### The detection and releasing function shall be provided by a control unit listed to UL 864 for releasing service and installed in accordance with NFPA 72.

−

−### A general-purpose fire alarm control unit not specifically listed for releasing service shall not operate a pre-action or deluge valve.

−

−### The releasing control unit shall be provided with secondary (battery) power sized to carry the system through the standby and alarm periods required by NFPA 72.

−

−### The releasing circuits shall meet the class and survivability required by NFPA 72 for the application.

−

−## Detection Type and Layout {toc}

−

−### The choice of detection device depends on the speed of detection required, the environment (temperature, dust, airflow, ceiling height), and the hazard. {note}

−

−### Detection devices shall be selected and spaced for the hazard and the protected environment in accordance with NFPA 72.

−

−```datasheet

−label: Releasing Detection Type

−type: select

−drawing_ref: true

−options:

− - "Spot smoke detectors"

− - "Spot heat detectors (fixed-temperature / rate-of-rise)"

− - "Linear (line-type) heat detection cable"

− - "Optical flame detectors (UV / IR)"

− - "Pneumatic rate-of-rise detection"

− - "Combination — see releasing matrix"

−default: "Spot smoke detectors"

−```

−

−### Detection devices shall be of a type listed for releasing service.

−

−### Flame detectors are common over flammable liquid and transformer hazards where the fastest possible response is required; linear heat detection suits cable trays and conveyors; spot smoke detection suits data centers and clean rooms where incipient detection is valued. {note}

−

−## Cross-Zoned Detection {toc}

−

−### Cross-zoning guards against an accidental release from a single faulty or transient detector signal, which is exactly the failure mode that pre-action and deluge systems exist to prevent. {note}

−

−### For releasing service, where cross-zoned (coincidence) logic is used, two separate detection zones or two separate detectors shall operate before a release signal is issued.

−

−```datasheet

−label: Detection Releasing Logic

−type: radio

−drawing_ref: true

−options:

− - "Cross-zoned detection (two zones / two detectors required)"

− - "Single detection zone (where accepted by AHJ)"

− - "Double interlock — cross-zoned detection AND low-air signal"

−default: "Cross-zoned detection (two zones / two detectors required)"

−```

−

−### On a single-interlock pre-action system, cross-zoned detection alone releases the valve.

−

−### On a double-interlock pre-action system, the releasing logic requires a cross-zoned (or single-zone, per the listing) detection signal together with the low-air signal.

−

−### The Contractor shall confirm acceptance of the proposed cross-zoning arrangement with the AHJ and, where applicable, the insurer before finalizing the design, because cross-zoned detection is not accepted in every jurisdiction and is not universally FM-approved.

−

−## Manual Release and Abort {toc}

−

−### Where the sequence of operations and the AHJ permit, an abort or delay function may be provided.

−

−```datasheet

−label: Manual Controls Provided

−type: checkbox

−options:

− - "Manual release station (releasing-service listed)"

− - "Manual emergency release at valve"

− - "Abort / delay function (only where AHJ permits)"

−default: "Manual release station (releasing-service listed)"

−```

−

−### A manual release station shall be provided at the protected area or at the valve, listed for releasing service, allowing trained personnel to trip the valve manually.

−

−### Abort and delay functions shall be applied only where they are explicitly permitted, because they introduce a delay into a life-safety releasing function.

−

−### The manual release shall remain capable of operating the valve independent of the abort function.

−

−# Valves and Trim {toc}

−

−## Pre-Action / Deluge Valve {toc}

−

−### The pre-action or deluge valve is a listed valve held closed by a pilot/priming arrangement and operated by the releasing solenoid (electric release), a pneumatic actuator (pneumatic release), or both, in the combination defined by the system type and the listing. {note}

−### On electric release, the releasing control unit energizes or de-energizes the solenoid to vent the priming chamber and allow the valve to open. {note}

−

−### The valve type — single-interlock or double-interlock pre-action, or deluge — shall be specified for the system's hazard and release configuration.

−

−```datasheet

−label: Valve Type

−type: radio

−drawing_ref: true

−options:

− - "Single-interlock pre-action valve (electric release)"

− - "Double-interlock pre-action valve (electric/pneumatic release)"

− - "Deluge valve (electric release)"

− - "Deluge valve (electric/pneumatic release)"

−default: "Single-interlock pre-action valve (electric release)"

−```

−

−### The valve release method — electric, pneumatic, or both — shall be specified and shall be compatible with the selected valve type.

−

−```datasheet

−label: Valve Release Method

−type: radio

−options:

− - "Electric release (solenoid from releasing control unit)"

− - "Pneumatic release (pilot line / dry pilot actuator)"

− - "Electric and pneumatic (double interlock)"

−default: "Electric release (solenoid from releasing control unit)"

−```

−

−### The pre-action or deluge valve size shall be specified to match the hydraulic design of the system.

−

−```datasheet

−label: Valve Size

−type: select

−unit: in

−drawing_ref: true

−options:

− - "2 in."

− - "2-1/2 in."

− - "3 in."

− - "4 in."

− - "6 in."

− - "8 in."

−default: "4 in."

−```

−

−### The valve and the releasing solenoid shall be listed together as a compatible assembly.

−

−### Diaphragm valves are common on modern pre-action and deluge systems because a single valve body can be trimmed for single-interlock, double-interlock, or deluge service by changing the trim and release arrangement. {note}

−

−## Valve Trim {toc}

−

−### The valve assembly shall be furnished with the manufacturer's standard listed trim for the selected system type.

−

−### The valve assembly shall be furnished with the manufacturer's standard listed trim for the selected system type, and the trim shall not be field-assembled from non-listed parts.

−

−### The trim shall include a water-side pressure gauge and, on pre-action systems, a supervisory air/nitrogen-side gauge.

−

−### The trim shall include the priming line and pressure-operated relief or alarm port, and the release solenoid with its supervised wiring.

−

−### On pre-action systems the trim shall include a low-air supervisory switch, and on double-interlock systems that low-air switch shall be wired into the releasing interlock.

−

−### The trim shall include an intermediate chamber drain with sight observation to confirm the chamber is dry before resetting.

−

−### The trim shall include a main drain valve not smaller than 2 in., an automatic ball drip on the FDC supply piping, and the waterflow alarm pressure switch that signals when water enters the piping.

−

−## Supervisory Air / Nitrogen Supply {toc}

−

−### Pre-action systems shall be maintained under supervisory air or nitrogen so that the loss of pressure from an opened sprinkler or damaged pipe is detected.

−

−```datasheet

−label: Supervisory Gas Supply (pre-action)

−type: radio

−options:

− - "Dedicated air compressor with listed air maintenance device"

− - "Plant air through listed air maintenance device"

− - "Membrane nitrogen generator"

− - "Pressure-swing adsorption (PSA) nitrogen generator"

− - "Not applicable — deluge (open to atmosphere)"

−default: "Dedicated air compressor with listed air maintenance device"

−```

−### Deluge systems are open to atmosphere and are not air-supervised. {note}

−

−### Where the supervisory gas is air, an air compressor with a listed air maintenance device shall be provided, and the air maintenance device shall limit the rate of air introduction so that a small leak is not masked by an oversized restoration capacity.

−

−```datasheet

−label: Air Compressor Restoration Time (pre-action)

−type: range

−unit: min

−options:

− min: 15

− max: 60

− setpoints: [15, 30, 45, 60]

−default: 30

−```

−

−### Where the supervisory gas is nitrogen, a listed nitrogen generator (membrane or pressure-swing adsorption) shall be provided, producing at least 98 percent nitrogen at the valve and purged to the listed purity at the most remote sprinkler.

−

−```datasheet

−label: Nitrogen Purity at Sprinkler (pre-action, where used)

−type: range

−unit: '%'

−options:

− min: 90

− max: 99

− setpoints: [90, 95, 98, 99]

−default: 98

−```

−

−### Nitrogen is the preferred supervisory gas for data centers and freezer warehouses because it eliminates the oxygen that drives internal corrosion over the long service life of these critical assets. {note}

−

−## Valve and Detection Supervision {toc}

−

−```datasheet

−label: Supervisory Signals

−type: checkbox

−options:

− - "Main control valve tamper switch"

− - "Low air / nitrogen pressure switch (pre-action)"

− - "Release solenoid circuit supervision"

− - "Detection circuit supervision"

− - "Valve room low-temperature switch (40°F)"

−default: "Main control valve tamper switch"

−```

−

−### The water supply control valve and any other valves controlling water to the system shall be supervised open by an electrically supervised tamper switch connected to the fire alarm system or supervising station per NFPA 72 and NFPA 13.

−

−### The release solenoid wiring, the detection circuits, and, on pre-action systems, the supervisory air pressure shall all be electrically supervised so that any open, ground, loss of solenoid continuity, or low-air condition produces a trouble signal.

−

−### NFPA 13 requires the system piping and the detection devices to be automatically supervised where there are more than 20 sprinklers on the system.

−

−# Piping and Sprinklers {toc}

−

−## Closed Heads (Pre-Action) vs. Open Heads (Deluge) {toc}

−

−### Pre-action systems use closed (automatic) sprinklers in which the thermal element holds the orifice closed until heat opens the individual sprinkler; deluge systems use open sprinklers or directional spray nozzles with no thermal element, every device permanently open and discharging the instant the valve trips. {note}

−

−### The discharge device type shall be specified as closed sprinklers for pre-action service or open sprinklers or nozzles for deluge service.

−

−```datasheet

−label: Discharge Device Type

−type: select

−drawing_ref: true

−options:

− - "Closed upright sprinklers (pre-action)"

− - "Closed dry-pendent / dry-sidewall sprinklers (pre-action)"

− - "Open sprinklers (deluge)"

− - "Open directional spray nozzles (deluge)"

−default: "Closed upright sprinklers (pre-action)"

−```

−

−### The sprinkler or nozzle K-factor shall be specified consistent with the hydraulic demand of the discharge device selected for the system.

−

−```datasheet

−label: Sprinkler / Nozzle K-Factor

−type: select

−drawing_ref: true

−options:

− - "K-5.6 (standard commercial)"

− - "K-8.0 (large orifice)"

− - "K-11.2 (extra large orifice)"

− - "K-14.0"

−default: "K-5.6 (standard commercial)"

−```

−

−### Where closed heads are used in pre-action service, the sprinkler thermal response shall be specified as standard or quick response.

−

−```datasheet

−label: Sprinkler Thermal Response (pre-action closed heads)

−type: radio

−options:

− - "Standard Response"

− - "Quick Response"

− - "Not applicable — open heads (deluge)"

−default: "Standard Response"

−```

−

−### Where closed heads are used in pre-action service, the sprinkler temperature rating shall be specified based on the anticipated ceiling temperature.

−

−```datasheet

−label: Sprinkler Temperature Rating (pre-action closed heads)

−type: select

−options:

− - "Ordinary (135°F–170°F)"

− - "Intermediate (175°F–225°F)"

− - "High (250°F–300°F)"

− - "Not applicable — open heads (deluge)"

−default: "Ordinary (135°F–170°F)"

−```

−

−### Pre-action systems shall use closed (automatic) sprinklers listed to UL 199.

−

−### Standard pendent sprinklers shall not be used where residual water could collect and freeze; upright and listed dry-pendent sprinklers are the common orientations in pre-action service.

−

−### Open nozzles for deluge service shall be selected for the discharge pattern, K-factor, and throw required by the hazard, and shall be installed in the orientation and at the spacing on which the hydraulic design is based.

−

−## Piping Materials and Corrosion Control {toc}

−

−### Steel pipe shall conform to ASTM A795 or ASTM A53; ASTM A795 is the purpose-written fire protection standard and is preferred.

−

−```datasheet

−label: Steel Pipe Standard

−type: radio

−options:

− - "ASTM A795 (galvanized) — preferred"

− - "ASTM A795 (black) — pre-action with nitrogen inerting only"

− - "ASTM A53 (galvanized)"

− - "ASTM A53 (black) — pre-action with nitrogen inerting only"

−default: "ASTM A795 (galvanized) — preferred"

−```

−### The galvanized variant is strongly preferred over black for these normally dry systems unless a pre-action system is also nitrogen-inerted, because internal corrosion in cycled wet-dry environments is significantly more aggressive than in continuously wet systems. {note}

−

−### Steel pipe shall conform to ASTM A795 or ASTM A53, with ASTM A795 preferred.

−

−### Schedule 40 pipe shall be used for threaded joints in sizes 3 in. and smaller; Schedule 10 listed for dry-system service or Schedule 40 may be used for grooved or welded joints.

−

−```datasheet

−label: Primary Joining Method

−type: select

−options:

− - "Threaded (Schedule 40 only, 3 in. and smaller)"

− - "Grooved mechanical coupling (listed, 1 in. and larger)"

− - "Welded (Schedule 40, 1 in. and larger)"

− - "Grooved mains / threaded branch lines"

−default: "Grooved mains / threaded branch lines"

−```

−

−### Schedule 10 pipe shall not be threaded.

−

−### CPVC pipe shall not be used.

−

−### Galvanized pipe that is field-cut, threaded, or welded shall be touched up with a listed cold-galvanizing compound to restore the corrosion protection at the most corrosion-prone location in the system.

−

−### Galvanized fittings shall be used with galvanized pipe.

−

−### Threaded joints shall use listed fire protection thread sealant applied to male threads only, and PTFE tape shall not be the sole sealant.

−

−### On pre-action systems, threaded joints shall be assembled for air-tightness as well as water-tightness because the system shall meet the air-leakage limit.

−

−### Grooved coupling gaskets shall be compatible with the supervisory gas (EPDM is acceptable for air and nitrogen) and the coupling torque shall be confirmed at every joint.

−

−### Welding shall be performed by qualified welders, weld joints visually inspected for full penetration, and galvanized pipe weld areas repaired with cold-galvanizing compound.

−

−# Drainage {toc}

−

−## Pipe Pitch {toc}

−

−### Pitch is the primary mechanism by which residual water — from a hydrostatic test, a release, condensation, or a partial trip-and-reset — is removed. {note}

−### Inadequate pitch leaves trapped water that corrodes the pipe and, in cold applications, freezes and ruptures it. {note}

−

−### System piping shall be pitched to drain back to the valve or to auxiliary drains at low points.

−

−### NFPA 13 requires minimum pitch of 1/2 in. per 10 ft for branch lines and 1/4 in. per 10 ft for mains in steel-pipe systems.

−

−```datasheet

−label: Minimum Branch Line Pitch

−type: range

−unit: in per 10 ft

−options:

− min: 0.5

− max: 2.0

− setpoints: [0.5, 1.0, 1.5, 2.0]

−default: 0.5

−```

−

−```datasheet

−label: Minimum Main Pitch

−type: range

−unit: in per 10 ft

−options:

− min: 0.25

− max: 1.0

− setpoints: [0.25, 0.5, 0.75, 1.0]

−default: 0.25

−```

−

−### Deluge piping shall drain completely after every operation, because the open piping admits and retains test and discharge water at every low point.

−

−## Auxiliary Drains and Main Drain {toc}

−

−### Drum drips and the main drain shall be drained as part of seasonal maintenance and after every release; missed drainage is a leading cause of corrosion and, in cold applications, of freeze damage.

−### The drainage layout shall be shown on the pitch and drainage plan: [[drawing: pipe pitch and drainage plan with all auxiliary drain locations and elevations]].

−

−```datasheet

−label: Auxiliary Drain Configuration

−type: radio

−drawing_ref: "pitch and drainage plan"

−options:

− - "Single drain valve at each trapped low point"

− - "Two-valve drum drip assembly (isolation and drain valves)"

−default: "Two-valve drum drip assembly (isolation and drain valves)"

−```

−

−```datasheet

−label: Main Drain Discharge Location

−type: select

−options:

− - "Floor drain — interior heated valve room"

− - "Exterior discharge at grade"

− - "Discharge to storm system"

−default: "Floor drain — interior heated valve room"

−```

−

−### Auxiliary drains (drum drips) shall be provided at every trapped low point where water cannot drain back to the main drain by gravity, and shall be located so they can be reached for routine drainage.

−

−### A main drain valve not smaller than 2 in. shall be provided at the valve assembly.

−

−# Water Supply and Fire Pump Interface {toc}

−

−## Deluge systems impose a large simultaneous demand because every open device flows at once, and double-interlock pre-action systems must overcome the dry-pipe delivery delay; both frequently require a fire pump.

−

−```datasheet

−label: Fire Pump Required

−type: radio

−options:

− - "No — public supply adequate (see hydraulic calculations)"

− - "Yes — electric-driven fire pump per NFPA 20"

− - "Yes — diesel-driven fire pump per NFPA 20"

−default: "No — public supply adequate (see hydraulic calculations)"

−```

−

−```datasheet

−label: Fire Department Connection Type

−type: radio

−options:

− - "Siamese (two 2-1/2 in. inlets)"

− - "Single 4 in. large-diameter-hose inlet"

− - "Siamese plus one 4 in. large-diameter-hose inlet"

−default: "Siamese (two 2-1/2 in. inlets)"

−```

−

−```datasheet

−label: FDC Identification Sign

−type: select

−options:

− - "\"AUTO SPKR — PREACTION\" per NFPA 13"

− - "\"AUTO SPKR — DELUGE\" per NFPA 13"

− - "System-type sign plus zone identification"

−default: "\"AUTO SPKR — PREACTION\" per NFPA 13"

−```

−

−## The water supply shall meet the system demand plus the hose stream allowance with the NFPA 13 safety margin.

−

−## Where a fire pump is provided, it shall be installed under [[sync/fire-pumps]] in accordance with NFPA 20, and the releasing matrix shall coordinate pump start with valve release so that pressure and flow are available when the valve trips.

−

−## The fire department connection shall be provided per NFPA 13 and the IFC, with an automatic ball drip on the FDC supply piping and a sign identifying the system type.

−

−# Testing and Commissioning {toc}

−

−## Flushing and Hydrostatic Test {toc}

−

−```datasheet

−label: Hydrostatic Test Pressure

−type: range

−unit: psi

−options:

− min: 200

− max: 400

− setpoints: [200, 250, 300, 350, 400]

−default: 200

−```

−

−```datasheet

−label: Hydrostatic Test Duration

−type: radio

−unit: hours

−options:

− - "2 hours"

−default: "2 hours"

−```

−

−### The piping shall be flushed before sprinklers or open nozzles are installed, in accordance with NFPA 13 and NFPA 24, until the effluent runs clear.

−

−### All piping shall be hydrostatically tested at 200 psi for 2 hours with no pressure loss and no visible leaks; where working pressure exceeds 150 psi the test pressure shall be working pressure plus 50 psi.

−

−### After the witnessed hydrostatic test the system shall be thoroughly drained, including every auxiliary drain, before being placed in service.

−

−## Air Pressure Test (Pre-Action) {toc}

−

−### The air test detects joint leaks that sealed under water pressure but leak air. {note}

−### Deluge systems, being open to atmosphere, are not air-tested. {note}

−

−### Pre-action systems shall be air-tested at 40 psi for 24 hours with a pressure loss not exceeding 1.5 psi, in accordance with NFPA 13, after the system is drained from the hydrostatic test and before it is placed in service.

−

−```datasheet

−label: Air Test (pre-action) Allowable Loss

−type: radio

−unit: psi/24 hr

−options:

− - "1.5 psi per 24 hours (NFPA 13)"

− - "Not applicable — deluge (open to atmosphere)"

−default: "1.5 psi per 24 hours (NFPA 13)"

−```

−

−### Leaks shall be located by soap-bubble or ultrasonic testing and corrected before retest.

−

−## Valve Trip Test and Water Delivery Time {toc}

−

−### The trip test confirms the calculated trip-time and water-delivery values in practice. {note}

−

−### The pre-action or deluge valve shall be trip-tested by operating the detection system (and, for double-interlock systems, also venting the supervisory air) and confirming that the releasing control unit issues the release signal, the solenoid operates, the valve opens, and the alarm signals transmit.

−

−### For pre-action systems the test shall confirm that water reaches the inspector's test connection at the most remote point.

−

−### For double-interlock pre-action and deluge systems the measured water delivery time from operation to discharge shall not exceed 60 seconds, consistent with the dry-pipe water delivery rule.

−

−```datasheet

−label: Maximum Water Delivery Time at Trip Test

−type: range

−unit: seconds

−options:

− min: 15

− max: 60

− setpoints: [15, 20, 30, 40, 50, 60]

−default: 60

−```

−

−### Where the field-measured time exceeds the calculated value the cause shall be investigated and corrected.

−

−### The full releasing matrix shall be verified — each initiating device or zone, the cross-zoned logic, each releasing output, and each interlock (HVAC shutdown, damper, equipment power-down) — and the results recorded.

−

−```datasheet

−label: Trip Test Scope

−type: checkbox

−options:

− - "Detection-initiated release (full sequence)"

− - "Double-interlock: detection plus low-air, both required to release"

− - "Manual release station operation"

− - "Releasing matrix verified device-by-device"

− - "Interlocks verified (HVAC, dampers, equipment shutdown)"

− - "Water delivery time measured and recorded"

−default: "Detection-initiated release (full sequence)"

−```

−

−## Partial-Flow and Solenoid Tests {toc}

−

−### Where a full discharge test would damage the protected space — the usual case for deluge systems over transformers, electronics, or aircraft — the trip test may be performed as a partial-flow or no-flow test using the manufacturer's test arrangement.

−

−```datasheet

−label: Deluge / Pre-Action Acceptance Test Method

−type: radio

−options:

− - "Full-flow trip test (where discharge is acceptable)"

− - "Partial-flow test to test header"

− - "No-flow solenoid / logic test per manufacturer (sensitive areas)"

−default: "Full-flow trip test (where discharge is acceptable)"

−```

−

−### The acceptance test method shall be the one specified in the valve manufacturer's listing and instructions and accepted by the AHJ.

−

−### At minimum, the releasing solenoid, the detection-to-release logic, and the alarm transmission shall be verified at acceptance.

−

−## Main Drain Test and Certificates {toc}

−

−```datasheet

−label: Main Drain Residual Pressure at Acceptance

−type: range

−unit: psi

−drawing_ref: true

−options:

− min: 10

− max: 180

− setpoints: [10, 20, 30, 40, 50, 60, 70, 80, 100, 120, 150, 180]

−default: 50

−```

−

−### The main drain shall be fully opened with all supply valves open, and the static and residual flowing pressures recorded as the baseline for future NFPA 25 tests.

−

−### The Contractor shall complete and sign the Contractor's Material and Test Certificate for Aboveground Piping (NFPA 13 Figure 29.1.1) and the NFPA 72 Record of Completion for the detection and releasing system, and shall schedule an acceptance inspection with the AHJ.

−

−### The system shall not be placed in service until the AHJ has witnessed the required tests and issued approval.

−

−# Installation {toc}

−

−## Pipe Routing and Coordination {toc}

−

−### Working drawings approved by the AHJ govern the routing, sizing, and arrangement of all piping. {note}

−### Routing changes are particularly consequential because they affect system volume, water delivery time, drainage, and the open-nozzle hydraulic balance on deluge systems. {note}

−

−### Deviations from the approved working drawings require a revised submittal or written approval from the Engineer of Record and the AHJ.

−

−### Piping shall be routed to maintain the required pitch; where obstructions force a deviation, an auxiliary drain shall be provided at the resulting low point.

−

−### The detection layout, releasing control unit location, and conduit routing shall be coordinated with the sprinkler piping so that detector spacing and releasing circuit survivability are not compromised by field changes.

−

−## Cutting, Fabrication, and Protection {toc}

−

−### Pipe shall be cut square, reamed to remove burrs, and grooved to the coupling manufacturer's dimensions.

−

−### All open pipe ends shall be capped when work is not in progress to keep out debris, which is especially damaging to the small orifices in the valve trim, the releasing solenoid, and open deluge nozzles.

−

−### Galvanized pipe field-cut, threaded, or welded shall be touched up with cold-galvanizing compound.

−

−### Detection devices shall be protected from construction dust and shall not be placed in service until the space is clean enough that nuisance operation will not occur.

−

−# Hangers and Seismic Bracing {toc}

−

−## Seismic joint failure is especially consequential on these systems because loss of supervisory air or damage to the releasing/pilot lines can produce a trouble condition or, on a single-interlock system already in the released state, an unintended discharge. {note}

−

−## Hangers shall be listed for fire protection use and installed per NFPA 13 Chapter 17, sized for the water-filled pipe weight because the pipe fills with water during hydrostatic testing and after every release.

−

−## Where the building is in Seismic Design Category C, D, E, or F per ASCE 7 and the IBC, lateral and longitudinal seismic bracing shall be provided per NFPA 13 Chapter 18, with flexible couplings at the prescribed locations.

−

−```datasheet

−label: Seismic Design Category

−type: select

−drawing_ref: true

−options:

− - "A"

− - "B"

− - "C"

− - "D"

− - "E"

− - "F"

−default: "B"

−```

−

−```datasheet

−label: Seismic Bracing Required

−type: radio

−options:

− - "No — SDC A or B"

− - "Yes — SDC C"

− - "Yes — SDC D, E, or F (full bracing per NFPA 13 Chapter 18)"

−default: "No — SDC A or B"

−```

−

−# Delivery, Storage, and Handling {toc}

−

−## Detectors and the releasing control unit are electronic devices and shall be protected from construction dust and humidity until the space is ready.

−

−```datasheet

−label: On-Site Storage Conditions

−type: select

−options:

− - "Indoor conditioned storage, original packaging"

− - "Indoor unconditioned storage, protected from moisture"

− - "Per manufacturer requirements"

−default: "Indoor conditioned storage, original packaging"

−```

−

−## Sprinklers, open nozzles, valves, detectors, and the releasing control unit shall be delivered in the manufacturer's original packaging and stored indoors in a clean, dry, conditioned space protected from impact, moisture, dust, and temperature extremes.

−

−## Sprinklers and open nozzles shall not be dropped or otherwise subjected to impact, and any device that has been dropped or shows physical damage shall be discarded, not installed.

−

−## Pipe shall be stored off the ground with end caps in place to keep the interior clean.

−

−# Warranty {toc}

−

−## The warranty shall run from the date of substantial completion and shall cover the complete installed system including pipe, fittings, hangers, seismic bracing, the pre-action or deluge valve, the releasing control unit, detectors, the release solenoid, the air or nitrogen supply (pre-action), alarm and supervisory devices, the fire department connection, and all specialties.

−

−```datasheet

−label: Installation Warranty Period

−type: select

−options:

− - "1 year from substantial completion"

− - "2 years from substantial completion"

−default: "1 year from substantial completion"

−```

−

−```datasheet

−label: Impairment Response Time

−type: radio

−unit: hours

−options:

− - "4 hours maximum for restoration or alternative protection"

− - "As required by AHJ impairment plan"

−default: "4 hours maximum for restoration or alternative protection"

−```

−

−## The Contractor shall warrant all materials and workmanship against defects for the project warranty period, running from the date of substantial completion.

−

−## Sprinklers and open nozzles carry individual manufacturer's limited warranties that the Contractor shall pass through to the Owner.

−

−## Warranty service shall include investigation of any persistent supervisory-trouble or low-air conditions, which on these systems can indicate a developing joint leak, a detector fault, or a releasing-circuit problem that was not present at acceptance but emerges as the installation ages.

−

−## Any impairment shall be handled per NFPA 25 impairment procedures with prompt notification to the Owner, the monitoring station, the fire department, and the insurer.

−

−# Spare Parts {toc}

−

−## The Contractor shall turn over the spare releasing components recommended by the valve and panel manufacturers, because a failed solenoid or detector impairs the entire system and these items are not always locally stocked.

−

−```datasheet

−label: Spare Sprinkler / Nozzle Cabinet Quantity

−type: select

−options:

− - "6 devices (≤300 installed)"

− - "12 devices (301–1,000 installed)"

− - "24 devices (>1,000 installed)"

−default: "6 devices (≤300 installed)"

−```

−

−```datasheet

−label: Spare Releasing Components Provided

−type: checkbox

−options:

− - "Spare release solenoid"

− - "Spare detectors (each type installed)"

− - "Spare valve trim gaskets / diaphragm"

− - "Sprinkler wrench for each sprinkler type"

−default: "Spare release solenoid"

−```

−

−## The Contractor shall provide a cabinet of spare sprinklers (or spare open nozzles, for deluge systems) and one sprinkler wrench of each type, mounted in the valve room or adjacent mechanical room, in accordance with NFPA 13.

−

−## The cabinet shall contain at minimum six devices for systems with up to 300 installed, 12 for 300 to 1,000, or 24 for systems over 1,000, and shall represent each type, orifice/K-factor, temperature rating (closed heads), and finish installed.

−

−## The Contractor shall turn over at minimum a spare release solenoid and the recommended spare detectors recommended by the valve and panel manufacturers.

−

−# Ongoing Inspection, Testing, and Maintenance {toc}

−

−## The system shall be inspected, tested, and maintained throughout the life of the building in accordance with NFPA 25 for the water-based portion and NFPA 72 for the detection and releasing portion, current adopted editions.

−

−```datasheet

−label: Service Agreement

−type: radio

−options:

− - "Combined service agreement (sprinkler and fire alarm contractors)"

− - "Separate agreements for NFPA 25 and NFPA 72 work"

− - "Owner-performed where qualified per NFPA 25 / NFPA 72"

−default: "Combined service agreement (sprinkler and fire alarm contractors)"

−```

−

−## NFPA 25 establishes intervals for inspecting components, testing alarm and supervisory devices, conducting main drain tests, performing the valve trip test, and servicing the air or nitrogen supply.

−

−## NFPA 72 establishes intervals for testing detectors, the releasing control unit, batteries, and the releasing circuits.

−

−## Supervisory air/nitrogen pressure and valve-room heating shall be inspected weekly or monthly on pre-action systems; waterflow and supervisory alarms shall be tested quarterly; the valve shall receive an annual full trip test including the complete releasing sequence; detector sensitivity shall be tested periodically per NFPA 72; and every auxiliary drain shall be drained seasonally and after every release.

−

−## The Owner shall maintain a service agreement with qualified fire protection and fire alarm service contractors, and records of all inspections and tests shall be retained on-site and available to the AHJ.

+---

+title: Pre-Action and Deluge Sprinkler Systems

+category: Fire Protection

+description: >

+ When to use: Automatic sprinkler systems designed to NFPA 13 in which the piping downstream of a pre-action or deluge valve is normally dry and water is admitted by a releasing control unit acting on a fire detection signal rather than by the opening of a sprinkler alone. Covers the decisions that exist only on these systems: the system type (non-interlock, single-interlock, and double-interlock pre-action, and deluge), the releasing detection and its initiating logic, the releasing control unit and its listing for releasing service, the release actuation of the valve, manual release and any release delay, the auxiliary functions tied to a release, the pre-action or deluge valve and its trim, the supervisory gas and its supply on a pre-action system, the water delivery time of a double-interlock system, the open discharge devices and zoning of a deluge system, and the trip test, releasing sequence tests, and air leakage test that prove the installation.

+ Not intended for: The sprinkler-system family baseline of hazard classification, design density and area, hose stream allowance, water supply, sprinkler selection and temperature rating, control valve supervision, hangers and seismic bracing, hydrostatic testing, warranty, and the spare sprinkler cabinet, which is carried by [[sync/wet-pipe-fire-sprinkler-systems]] and applies to systems furnished under this standard; pipe, fittings, and joining ([[sync/fire-protection-piping]]); the pitch, drainage, and interior corrosion provisions of dry piping, which are carried by [[sync/dry-pipe-fire-sprinkler-systems]] and apply to the dry piping of these systems; conventional dry-pipe systems that admit water on the loss of supervisory pressure alone ([[sync/dry-pipe-fire-sprinkler-systems]]); the fire alarm control unit, initiating device circuits, and notification beyond the releasing service that operates these valves ([[sync/fire-alarm-systems]]); clean agent systems for spaces where no water is acceptable ([[sync/clean-agent-fire-suppression]]); fire pumps ([[sync/fire-pumps]]); standpipes ([[sync/standpipe-systems]]); foam-water systems, which add the proportioning and concentrate provisions of NFPA 16; and water spray fixed systems whose nozzle layout is designed under NFPA 15, for which this standard governs only the deluge valve, its detection, and its releasing.

+---

+# Scope {toc}

+## This standard covers the system type, the releasing detection and control, the pre-action or deluge valve and its enclosure, the supervisory gas supply of a pre-action system, water delivery time, the discharge devices and zoning of a deluge system, and the acceptance tests specific to a sprinkler system that admits water on a detection signal. {note}

+## In a pre-action system, closed sprinklers sit on piping held under supervisory air or nitrogen, and a releasing control unit opens the pre-action valve on a detection signal, on the loss of supervisory pressure, or on both together, according to the interlock; water then discharges only where heat has opened a sprinkler. In a deluge system, open sprinklers or nozzles sit on piping open to atmosphere, and water discharges from every device at once when the detection signal opens the deluge valve. {note}

+## This standard is the pre-action and deluge layer over [[sync/wet-pipe-fire-sprinkler-systems]]. The family standard establishes how a sprinkler system is classified, sized, supplied, valved, supported, tested, spared, and warranted; this standard establishes what changes when a detection system decides when water enters the pipe: the interlock, the detection and the panel that release the valve, the valve itself, the gas that supervises a pre-action system, the delay before water arrives, and the tests that prove the sequence. {note}

+## Pre-action and deluge systems furnished under this standard shall also comply with [[sync/wet-pipe-fire-sprinkler-systems]].

+## Where a requirement of this standard and a requirement of [[sync/wet-pipe-fire-sprinkler-systems]] address the same subject, the requirement of this standard shall govern.

+## Hazard classification, design density and area, hose stream allowance, water supply verification, sprinkler selection and temperature rating, control valve supervision, hangers and seismic bracing, hydrostatic testing, warranty, and the spare sprinkler cabinet for systems furnished under this standard shall be as required by [[sync/wet-pipe-fire-sprinkler-systems]].

+## Pipe, fittings, and joints for systems furnished under this standard shall be as required by [[sync/fire-protection-piping]].

+## The pitch, auxiliary drains, inspector's test connection arrangement, interior corrosion protection, and refrigerated-space provisions of the dry piping downstream of each pre-action or deluge valve shall be as required for dry piping by [[sync/dry-pipe-fire-sprinkler-systems]].

+## The dry piping of a pre-action or deluge system holds the same standing water, the same oxygen, and the same freeze exposure as the piping of a dry-pipe system, and the provisions that manage them are the same provisions; this standard invokes them rather than restating them. {note}

+## The extent of each pre-action or deluge system and the location of each pre-action or deluge valve shall be as indicated on [[drawing: the fire protection plans and riser diagram]].

+## The following are outside the scope of this standard: {note}

+- Dry-pipe systems, which admit water on the loss of supervisory pressure alone with no detection system, and which are covered by [[sync/dry-pipe-fire-sprinkler-systems]]

+- The fire alarm control unit, initiating device circuits, notification appliances, and supervising station connection beyond the releasing service that operates these valves, which are covered by [[sync/fire-alarm-systems]]

+- Clean agent systems protecting spaces where no water discharge is acceptable, which are covered by [[sync/clean-agent-fire-suppression]]

+- Fire pumps and the pressure they add to the supply, which are covered by [[sync/fire-pumps]]

+- The fire department connection, its check valve, and its automatic drain, which are covered by [[sync/fire-department-connections]]

+- Standpipes and hose connections, which are covered by [[sync/standpipe-systems]]

+- A plant compressed air system that supplies more than the pre-action systems, which is covered by [[sync/compressed-air-systems]]

+- Foam-water sprinkler and foam-water deluge systems, which add the concentrate, proportioning, and discharge duration provisions of NFPA 16

+- Water spray fixed systems designed under NFPA 15, whose nozzle selection, spacing, and density are outside this standard even where the deluge valve, its detection, and its releasing are furnished under it

+- Systems protecting storage occupancies under the storage chapters of NFPA 13, whose density, in-rack, and delivery provisions are outside this standard

+# Referenced Standards {toc}

+## Equipment, materials, and installation shall comply with the latest adopted edition of each of the following unless a specific edition is cited.

+## Where referenced standards conflict, the more stringent requirement shall govern unless the Engineer of Record directs otherwise in writing.

+| Standard | Title |

+|----------|-------|

+| NFPA 13 | Standard for the Installation of Sprinkler Systems |

+| NFPA 15 | Standard for Water Spray Fixed Systems for Fire Protection |

+| NFPA 16 | Standard for the Installation of Foam-Water Sprinkler and Foam-Water Spray Systems |

+| NFPA 25 | Standard for the Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems |

+| NFPA 70 | National Electrical Code |

+| NFPA 72 | National Fire Alarm and Signaling Code |

+| NFPA 409 | Standard on Aircraft Hangars |

+| UL 260 | Dry Pipe and Deluge Valves for Fire-Protection Service |

+| UL 268 | Smoke Detectors for Fire Alarm Systems |

+| UL 521 | Heat Detectors for Fire Protective Signaling Systems |

+| UL 753 | Alarm Accessories for Automatic Water-Supply Control Valves for Fire-Protection Service |

+| UL 864 | Control Units and Accessories for Fire Alarm Systems |

+| FM 1011 | Approval Standard for Deluge and Preaction Sprinkler Systems |

+| FM Global Data Sheet 2-0 | Installation Guidelines for Automatic Sprinklers |

+| FM Global Data Sheet 2-1 | Corrosion in Automatic Sprinkler Systems |

+## Successive editions of NFPA 13 have changed the sprinkler count permitted on one pre-action valve, the water delivery provisions applied to a double-interlock system, the design area increase applied to it, and the supervision thresholds, and successive editions of NFPA 72 have changed the releasing circuit and detector spacing provisions, so the editions adopted by the Authority Having Jurisdiction settle which rule applies to a given project. {note}

+## The Contractor shall confirm the editions of NFPA 13 and NFPA 72 adopted by the Authority Having Jurisdiction before beginning the working drawings.

+# Submittals {toc}

+## Action Submittals {toc}

+### The Contractor shall submit the following for the Engineer of Record's review and return, together with the submittals required by [[sync/wet-pipe-fire-sprinkler-systems]], before the pre-action or deluge valve, the releasing control unit, the detection devices, or the dry piping is procured:

+- Product data for the pre-action or deluge valve and its trim, identifying the listing, the size, the body and trim materials, the release arrangement, the priming requirement, and the supervisory pressure range the manufacturer publishes for the selected arrangement

+- Product data for the releasing control unit, identifying its listing for releasing service, the releasing circuits, the secondary power calculation, and the compatibility listing with the solenoid it operates

+- Product data for each detection device, identifying its listing, its listed spacing, its temperature rating where it is a heat detector, and its operating temperature range

+- The releasing matrix, stating for each system every initiating device or zone, the initiating logic, the interlock inputs, the releasing output, the release delay where one is provided, the manual release and abort inputs, the alarm and supervisory outputs, and every auxiliary function operated on a release

+- Detection layout drawings showing every detector, its spacing, the ceiling height and construction it is spaced for, every manual release station, and the releasing control unit location

+- Product data for the supervisory gas source of each pre-action system, identifying the compressor or nitrogen generator, its capacity, the air maintenance device, the dryer, and the relief valve

+- The calculated volume of each double-interlock system and the water delivery time calculation for each system subject to the delivery time requirement

+- The deluge zone layout showing every open sprinkler or nozzle, its listing, its orientation, and the zone it belongs to, with the hydraulic calculation covering every device on the zones assumed to operate together

+- The valve enclosure heating provision, where the enclosure is not a heated room of the building

+```datasheet

+label: Action Submittals Required

+type: checkbox

+options:

+ - "Pre-action or deluge valve and trim product data"

+ - "Releasing control unit product data"

+ - "Detection device product data"

+ - "Releasing matrix"

+ - "Detection layout drawings"

+ - "Supervisory gas source product data"

+ - "System volume and water delivery time calculation"

+ - "Deluge zone layout and hydraulic calculation"

+ - "Valve enclosure heating provision"

+default:

+ - "Pre-action or deluge valve and trim product data"

+ - "Releasing control unit product data"

+ - "Detection device product data"

+ - "Releasing matrix"

+ - "Detection layout drawings"

+```

+### The releasing control unit shall not be programmed, and the detection devices shall not be installed, until the releasing matrix has been reviewed and returned.

+### The releasing matrix is the one document on which the sprinkler side and the detection side of the system agree about what causes water to enter the pipe. A valve released by a logic no one reviewed is the way a single failed detector floods a data hall, and the matrix is where that logic is read before it is wired. {note}

+## Closeout Submittals {toc}

+### The Contractor shall submit the following before the pre-action or deluge system is accepted, in addition to the closeout submittals required by [[sync/wet-pipe-fire-sprinkler-systems]]:

+- The trip test record for each valve, recording the initiating event, the time from the initiating event to the release signal, the time from the release signal to the valve opening, and, where water was flowed, the time to water at the inspector's test connection or at the most remote discharge device

+- The releasing sequence test record, recording the result of every row of the releasing matrix, including the confirmation that each interlock condition alone did not release a double-interlock valve

+- The air leakage test record for each pre-action system, recording the starting pressure, the pressure after 24 hours, and the ambient temperature at each reading

+- The as-left supervisory gas pressure and low-pressure supervisory setpoint for each pre-action system

+- The NFPA 72 record of completion for the releasing control unit and its detection, signed by the installer of that portion

+- The as-built releasing matrix and the releasing control unit program record

+- Operation and maintenance data covering the valve reset procedure, the releasing control unit, the detection devices and their sensitivity test intervals, the supervisory gas supply, and the NFPA 25 and NFPA 72 inspection and test intervals that apply to these systems

+```datasheet

+label: Closeout Submittals Required

+type: checkbox

+options:

+ - "Trip test record"

+ - "Releasing sequence test record"

+ - "Air leakage test record"

+ - "As-left supervisory pressure and setpoint"

+ - "NFPA 72 record of completion for the releasing portion"

+ - "As-built releasing matrix and program record"

+ - "Operation and maintenance data"

+default:

+ - "Trip test record"

+ - "Releasing sequence test record"

+ - "Air leakage test record"

+ - "As-left supervisory pressure and setpoint"

+ - "NFPA 72 record of completion for the releasing portion"

+ - "As-built releasing matrix and program record"

+ - "Operation and maintenance data"

+```

+# Quality Assurance {toc}

+## The individual who prepares the working drawings for the sprinkler side of the system shall have prepared the design of not fewer than three pre-action or deluge systems that were accepted by an Authority Having Jurisdiction.

+## The individual who prepares the releasing matrix and the detection layout shall hold the qualification for fire alarm system layout required by [[sync/fire-alarm-systems]] and by the Authority Having Jurisdiction.

+## Where the parties disagree whether a designer's experience meets that requirement, the Engineer of Record shall make the initial determination.

+## The Contractor shall identify on the working drawings the designer responsible for the sprinkler side and the designer responsible for the releasing side, and one entity shall be responsible to the Owner for the operation of the two together.

+## A pre-action or deluge system is two trades' work joined at a solenoid, and the acceptance test is where a gap between them is found. Naming a single responsible entity before the work starts is what keeps the gap from being discovered as a dispute over whose scope the releasing circuit was. {note}

+## The pre-action or deluge valve, its trim, the releasing solenoid, the air maintenance device, the nitrogen generator, and each detection device shall be listed for fire protection service.

+## The releasing control unit shall be listed to UL 864 for releasing device service, and a control unit that is not listed for releasing service shall not operate a pre-action or deluge valve.

+## The releasing solenoid shall be listed for use with the valve it operates and with the releasing control unit that drives it, and a solenoid, a valve, and a control unit from different manufacturers shall not be combined unless the combination is covered by a listing.

+## A releasing circuit is listed as a matched set because the panel's output current, the solenoid's coil, and the valve's release port are tested together; a solenoid that draws more than the circuit supplies opens late or not at all, and a circuit that supervises a coil it was not listed with reports trouble on a healthy solenoid. {note}

+## Where the Owner's property insurer requires it, the components named in this standard shall carry the insurer's approval in addition to the listing, in accordance with [[sync/wet-pipe-fire-sprinkler-systems]].

+# System Type and Sequence of Operation {toc}

+## System Type {toc}

+### The system type of each pre-action or deluge system shall be as indicated in the datasheet.

+```datasheet

+label: System Type

+type: select

+drawing_ref: "the fire protection riser diagram"

+options:

+ - "Non-interlock pre-action"

+ - "Single-interlock pre-action"

+ - "Double-interlock pre-action"

+ - "Deluge"

+```

+### The four types differ in what admits water to the pipe: {note}

+- A non-interlock pre-action system admits water on a detection signal or on the loss of supervisory pressure, whichever comes first, so a broken pipe fills the system as a dry-pipe system would while a detector fills it sooner.

+- A single-interlock pre-action system admits water on a detection signal alone, so a broken sprinkler or fitting in a room with no fire releases gas and reports a supervisory condition without admitting water, and a fire fills the pipe before the first sprinkler opens.

+- A double-interlock pre-action system admits water only when a detection signal and the loss of supervisory pressure coincide, so neither a failed detector nor a broken pipe admits water on its own, and water arrives after the first sprinkler opens with the delay of a dry-pipe system.

+- A deluge system has open discharge devices and admits water on a detection signal, discharging from every device on the zone at once.

+### The single interlock suits a space where the cost of water in the pipe after an unconfirmed detection is a drain-down, and where water waiting at the sprinkler when it opens is worth the exposure to a detection fault; the double interlock suits a space where water in the pipe without a fire is itself the loss, including piping that would freeze, at the cost of the dry-pipe delay and the enlarged design area; the non-interlock suits a space where the detection is wanted for early water rather than for protection against accidental discharge; and deluge suits a hazard that grows faster than sprinklers open in sequence, or a surface that must be wetted all at once. {note}

+### Where the protected space is held at or below 32°F, a system type that admits water on a detection signal alone shall not be used unless the Engineer of Record accepts in writing the drain-down and drying of the piping that follows every unconfirmed detection event.

+### Water admitted to freezer piping by a detector with no fire has minutes before it becomes ice, and the ice is removed by warming the piping or cutting it out; the double interlock exists so that an open sprinkler, which a fire produces and a detector fault does not, is a condition of admitting water. {note}

+### Where double-interlock pre-action is selected, the design area increase NFPA 13 applies to a dry-pipe system shall be applied under [[sync/wet-pipe-fire-sprinkler-systems]], and the delivery time requirement of this standard shall apply.

+### Where non-interlock or single-interlock pre-action is selected, the design area shall be the wet-pipe design area for the hazard under [[sync/wet-pipe-fire-sprinkler-systems]], with no increase for the system type.

+### NFPA 13 enlarges the design area of a double-interlock system because water is not in the pipe when the first sprinkler opens, so sprinklers open ahead of the water exactly as on a dry-pipe system. A non-interlock or single-interlock system fills on detection, ahead of the first sprinkler in the fire the detection was spaced to find, and so keeps the wet-pipe area. {note}

+### Not more than 1,000 automatic sprinklers shall be controlled by any one pre-action valve, in accordance with NFPA 13.

+### Where the sprinkler count of a pre-action system as drawn would exceed that limit, the Contractor shall subdivide the system into additional systems, each with its own valve, and shall report the subdivision to the Engineer of Record before the working drawings are submitted.

+## Sequence of Operation {toc}

+### The sequence of operation of each system shall be as stated in the reviewed releasing matrix, and the releasing control unit shall be programmed to that matrix and to no other logic.

+### On a detection signal that satisfies the initiating logic, the releasing control unit shall transmit a fire alarm signal to the building fire alarm system, shall operate the auxiliary functions the matrix assigns to the detection stage, and, where the interlock conditions of the system type are satisfied, shall operate the releasing output after any release delay indicated in the datasheet.

+### On a double-interlock system, the releasing control unit shall operate the releasing output only when the detection signal and the low-pressure supervisory signal from the system piping are both present, and either signal alone shall produce the alarm or supervisory signal assigned to it without operating the release.

+### On a non-interlock system, the loss of supervisory pressure shall open the valve through the valve trim without waiting for the releasing control unit, and the releasing control unit shall receive the low-pressure signal as a supervisory signal.

+### Water entering the piping shall initiate the waterflow alarm required under Waterflow Alarm, and the waterflow alarm shall be transmitted whether or not the releasing control unit initiated the release.

+### The waterflow alarm is transmitted on the water, not on the logic, so that a valve opened by the manual release, by the pilot line, or by a trim fault reports the same way a valve opened by the panel does. {note}

+### The releasing matrix shall assign each auxiliary function to the stage at which it operates, and a function assigned to the detection stage shall operate on the first detection signal whether or not the release follows.

+# Releasing Detection and Control {toc}

+## Releasing Control Unit {toc}

+### The releasing control unit arrangement shall be as indicated in the datasheet.

+```datasheet

+label: Releasing Control Unit Arrangement

+type: radio

+options:

+ - "Dedicated releasing control unit for each pre-action or deluge system"

+ - "One dedicated releasing control unit serving several systems"

+ - "Releasing function of the building fire alarm control unit"

+```

+### A dedicated releasing panel at each valve keeps the release logic, its power, and its detection on one small unit that a technician can isolate and test without touching the building system, and it reports to the building system as a single alarm and a single supervisory point; a shared releasing panel does the same for a group of valves in one location; and a building fire alarm control unit listed for releasing service can carry the logic itself, which removes a panel and a monitoring interface at the cost of putting the release logic in the same program as the rest of the building. {note}

+### Where the building fire alarm control unit performs the releasing function, its listing shall cover releasing device service, and the releasing circuits, their supervision, and their secondary power shall meet the requirements of this standard for a releasing control unit.

+### Each pre-action or deluge valve shall be operated by its own releasing circuit, and a releasing circuit shall not serve more than one valve unless the valves are designed to release together.

+### The releasing control unit shall be provided with secondary power that operates the unit in the standby condition for the period NFPA 72 requires for a releasing service unit and then operates the releasing output, the alarm outputs, and the auxiliary functions for the alarm period NFPA 72 requires.

+### The releasing control unit shall be supplied from a dedicated branch circuit in accordance with NFPA 72 and NFPA 70, and the circuit shall be identified at the panelboard as serving the fire sprinkler releasing service.

+### The releasing circuit to each solenoid shall be supervised for open, short, and ground conditions, and a fault on it shall produce a trouble signal at the releasing control unit and at the building fire alarm system.

+### The releasing circuits and the initiating device circuits of the releasing control unit shall be of the class and pathway survivability required by NFPA 72 for releasing service and selected under [[sync/fire-alarm-systems]].

+### The releasing control unit shall transmit its alarm, supervisory, and trouble signals to the building fire alarm system or to the supervising station in accordance with NFPA 72 and [[sync/fire-alarm-systems]].

+### The releasing control unit shall be located as indicated on [[drawing: the fire protection plans]].

+### The releasing control unit and its detection devices shall not be placed in service until the protected space is free of the construction dust and fumes that would operate the detection.

+### The disconnect that isolates the releasing output from the solenoid for testing shall be a listed disconnect that is supervised, so that a releasing circuit left disconnected after a test produces a trouble signal.

+### A releasing circuit disconnected for a test and not reconnected is the fault that leaves a room with detectors, a panel, and a valve that will never open, and a supervised disconnect is the only device that reports it. {note}

+## Releasing Detection {toc}

+### The detection types used for releasing service on the project shall be as indicated in the datasheet.

+```datasheet

+label: Releasing Detection Types

+type: checkbox

+options:

+ - "Spot smoke detectors"

+ - "Air-sampling smoke detection"

+ - "Spot heat detectors, fixed-temperature"

+ - "Spot heat detectors, rate-of-rise or rate-compensated"

+ - "Linear heat detection cable"

+ - "Optical flame detectors"

+ - "Heat-actuated devices on a pneumatic pilot line"

+ - "Wet pilot sprinkler line"

+ - "Dry pilot sprinkler line"

+```

+### The detection type used at each system shall be as indicated on [[drawing: the detection layout drawings]].

+### Each detection type answers a different environment: {note}

+- Spot smoke detectors and air-sampling detection find a fire before it produces the heat a sprinkler needs, and so give a pre-action system the time to fill before the first sprinkler opens; they suit a space with controlled airflow and no process smoke, and they do not suit a freezer, a dusty process area, or a space open to weather.

+- Fixed-temperature and rate-of-rise heat detectors are indifferent to dust, humidity, and airflow, and fixed-temperature units listed for low temperature are the spot detection that works in a freezer, at the cost of responding later than smoke detection.

+- Linear heat detection cable follows a conveyor, a cable tray, or a transformer, and detects along its length rather than at points.

+- Optical flame detectors respond within seconds to a flaming fire of a fuel they are listed for and are the detection that keeps up with a flammable liquid or a hangar floor, at the cost of a field of view that must be kept clear and a sensitivity to other radiant sources that the listing describes.

+- Heat-actuated devices on a pneumatic pilot line, and wet or dry pilot sprinkler lines, are detection without electrical circuits; the pilot line itself carries the release to the valve, and they suit a location where a releasing control unit, its power, and its wiring are not wanted in the hazard.

+### Detection devices used for releasing service shall be listed for that service and installed, spaced, and located in accordance with NFPA 72 for releasing service, including the spacing reductions NFPA 72 applies for ceiling height, ceiling construction, and airflow.

+### Heat detectors that release a non-interlock or single-interlock pre-action valve shall have a temperature rating lower than the rating of the sprinklers they precede and shall be spaced so that they operate before the sprinklers open.

+### On a system that fills on detection, a heat detector that opens after the sprinkler has admitted nothing before the sprinkler needed water, and the system has become a dry-pipe system with a panel in it. The detector rating and spacing are what put the water in the pipe first. {note}

+### Detection devices shall be listed for the temperature, humidity, and atmosphere of the space in which they are installed, and detectors in a space held at or below 32°F shall be listed for the lowest temperature of that space.

+### Where a pilot line is used, the pilot line shall be installed, sized, pitched, and protected as the valve manufacturer's listing requires, and a dry pilot line shall be supervised for the loss of pilot pressure.

+## Initiating Logic {toc}

+### The initiating logic by which the releasing control unit accepts a detection signal as a fire shall be as indicated in the datasheet.

+```datasheet

+label: Detection Initiating Logic

+type: radio

+options:

+ - "Single detector or single detection zone"

+ - "Cross-zoned detection, two detection zones"

+ - "Two detectors in one detection zone"

+ - "Not applicable, pilot line release"

+```

+### Single-detector logic releases the valve on the first detection and gives the earliest water; cross-zoned logic requires a detector on each of two interleaved zones, so that one failed or contaminated detector cannot release the valve and a fire in the space between two detectors is confirmed by both; and two-detector logic within one zone gives the same confirmation on an addressable system without the second circuit. Each is a listed arrangement, and the tradeoff is the second detection that a confirmed release waits for. {note}

+### Where cross-zoned or two-detector logic is selected, the first detection signal shall produce a fire alarm signal at the building fire alarm system and shall operate the auxiliary functions assigned to it, and the release shall follow the second detection signal.

+### Where cross-zoned or two-detector logic is selected, the detectors shall be spaced so that a fire at any point in the protected area is within the listed spacing of a detector on each zone, or of two detectors in the zone, as NFPA 72 requires for the logic selected.

+### Cross-zoned detection spaced as though it were single-zone detection leaves half the area within reach of only one zone, and a fire there produces an alarm that never becomes a release. {note}

+### The Contractor shall confirm the acceptance of the selected initiating logic with the Authority Having Jurisdiction and, where the Owner's insurer has a requirement, with the insurer before the releasing matrix is submitted.

+## Release Actuation {toc}

+### The means by which each pre-action or deluge valve is released shall be as indicated in the datasheet.

+```datasheet

+label: Release Actuation

+type: radio

+options:

+ - "Electric release by solenoid from the releasing control unit"

+ - "Pneumatic release by dry pilot line"

+ - "Hydraulic release by wet pilot line"

+ - "Electric and pneumatic release"

+default: "Electric release by solenoid from the releasing control unit"

+```

+### An electric release opens the valve on the releasing control unit's output through a solenoid on the trim, which is the arrangement every releasing logic, delay, abort, and auxiliary function is built on; a pneumatic or hydraulic release opens the valve when a pilot line loses pressure or gains it, with no panel between the detection and the valve, and suits a hazard without electrical service or where the detection is a pilot sprinkler line; and an electric and pneumatic release combines a solenoid with a pneumatic actuator on one trim, which is the trim arrangement of a double-interlock valve that uses the system's own supervisory pressure as the second interlock. {note}

+### Where the release actuation selected does not match the release arrangement the valve listing provides for the system type selected, the Contractor shall report the conflict to the Engineer of Record before the valve is procured.

+### Where electric release is selected, the solenoid shall be of the listed type for the valve and shall be arranged to fail in the position the listing assigns to it on loss of releasing circuit power, and the releasing matrix shall state whether the release is by energizing or by de-energizing the solenoid.

+### Where the release is by de-energizing the solenoid, the loss of power to the releasing circuit opens the valve, so the circuit and its secondary power must be as reliable as the detection; where the release is by energizing, a loss of power leaves the valve closed and reports trouble. The listing fixes which, and the matrix records it so the sequence tests check the right failure. {note}

+## Manual Controls and Release Delay {toc}

+### Each pre-action or deluge valve shall be provided with a manual emergency release on the valve trim that opens the valve without the releasing control unit and without electrical power.

+### The remote manual controls provided for each system shall be as indicated in the datasheet.

+```datasheet

+label: Remote Manual Controls

+type: checkbox

+options:

+ - "Remote manual release station at the protected area"

+ - "Remote manual release station at the releasing control unit"

+ - "Abort / delay function"

+```

+### Where a remote manual release station is provided, it shall be listed for releasing service, shall be located as indicated on [[drawing: the detection layout drawings]], shall be identified as the manual release for the system it operates, and shall be protected against accidental operation by a listed cover.

+### A remote manual release lets the occupant who sees the fire open the valve before the detection confirms it, which on a hangar or a process area is the difference the detection spacing was chosen to close; a station placed where it can be operated in passing is a valve opened by a coat sleeve. {note}

+### An abort or delay function shall be provided only where the Authority Having Jurisdiction accepts it in writing for the system, and its operation shall be stated in the releasing matrix.

+### The release delay applied between the satisfied initiating logic and the releasing output shall be as indicated in the datasheet.

+```datasheet

+label: Release Delay

+type: range

+unit: s

+min: 0

+max: 60

+setpoints: [0, 10, 15, 20, 30, 45, 60]

+default: 0

+```

+### A delay gives the occupants of a deluge zone a pre-discharge warning and a chance to leave before every nozzle opens, and gives an operator a chance to abort a release the detection got wrong; each second of delay is a second the fire grows before water reaches it, which is why the function needs the acceptance of the Authority and a stated period rather than a preference. {note}

+### Where a release delay is provided, a pre-discharge alarm shall sound in the protected area for the duration of the delay, and the manual release shall bypass the delay.

+### Where an abort function is provided, it shall hold the release only while the abort switch is held operated, shall not reset the initiating logic, and shall not prevent the manual emergency release at the valve or the remote manual release station from opening the valve.

+## Auxiliary Functions on Release {toc}

+### The auxiliary functions the releasing control unit operates on a detection signal or a release shall be as indicated in the datasheet.

+```datasheet

+label: Auxiliary Functions on Release

+type: checkbox

+options:

+ - "Shutdown of air handling serving the protected area"

+ - "Closure of smoke or fire dampers at the protected area"

+ - "Emergency power off of equipment in the protected area"

+ - "Fire pump start signal"

+ - "Release of door holders and access control at the protected area"

+ - "Process or conveyor shutdown"

+```

+### The stage at which each auxiliary function operates, and the device or system it operates, shall be as stated in the releasing matrix.

+### Air handling that keeps running carries smoke away from the detectors that are waiting for it and carries water spray away from the fire; equipment that keeps running under water spray is the loss the water was meant to prevent; and a fire pump started on the release signal rather than on the pressure drop is at speed when the valve opens rather than seconds after. Which functions a project ties to the release is a decision of the Owner and the process, and the matrix is where it is written down. {note}

+### Each auxiliary function output shall be supervised or confirmed in the manner NFPA 72 requires for the function, and the interface to the system it operates shall be as indicated on [[drawing: the fire alarm interface schedule]].

+# Pre-Action and Deluge Valve {toc}

+## Valve and Trim {toc}

+### The pre-action or deluge valve shall be listed to UL 260 for the system type and release arrangement selected, and its actuation design shall be as indicated in the datasheet.

+```datasheet

+label: Valve Actuation Design

+type: select

+options:

+ - "Diaphragm-actuated valve"

+ - "Clapper valve with latch"

+default: manufacturer

+```

+### A diaphragm valve is held closed by supply pressure on a diaphragm chamber and opens when the release vents the chamber, and one body is trimmed for non-interlock, single-interlock, double-interlock, or deluge service by changing the trim; a latched clapper valve is held by a mechanical latch that the release trips and is reset by hand. Either is listed for the service, and the choice follows the manufacturer's line unless the project has a reason to fix it. {note}

+### The pre-action or deluge valve size shall be as indicated in the datasheet.

+```datasheet

+label: Pre-Action or Deluge Valve Size

+type: range

+unit: in.

+drawing_ref: "the fire protection riser diagram"

+min: 1.5

+max: 8

+setpoints: [1.5, 2, 2.5, 3, 4, 6, 8]

+default: deferred

+```

+### The valve shall be installed with the manufacturer's listed trim for the system type and release actuation selected, and the trim shall not be assembled in the field from components that are not part of the listing.

+### Where the valve listing calls for priming water, the trim shall include the priming water connection, a means to confirm the priming level without opening the valve, and, where the listing provides one, a priming water level supervisory switch.

+### The trim shall include a water-side pressure gauge and, on a pre-action system, a supervisory gas pressure gauge, each readable from the floor of the valve enclosure.

+### On a pre-action system the trim shall include a low-pressure supervisory switch on the system piping, and on a double-interlock system that switch, or a second switch provided for the purpose, shall be the low-pressure input to the releasing interlock.

+### The trim shall include the releasing solenoid or the pneumatic or hydraulic actuator for the release actuation selected, the manual emergency release, and an alarm pressure switch on the valve's alarm outlet.

+### The trim shall include a drain for the diaphragm chamber or intermediate chamber, arranged so that the chamber can be confirmed drained before the valve is reset.

+### The main drain shall discharge where a full-flow trip test can be run without damage to the building.

+### The fire department connection shall enter the system on the system side of the pre-action or deluge valve, and the connection, its check valve, and the automatic drain between the check valve and the system shall be as required by [[sync/fire-department-connections]].

+### The fire department connection sign shall identify the connection as serving a pre-action system or a deluge system, and shall identify the zone where more than one deluge zone is served.

+### A permanent sign shall be provided at each valve stating the system type, the initiating logic, the release actuation, the release delay where one is provided, the normal supervisory gas pressure and low-pressure setpoint where the system is supervised by gas, the calculated and the tested water delivery time where the delivery time requirement applies, and the location of the releasing control unit, in addition to the signs required by [[sync/wet-pipe-fire-sprinkler-systems]].

+## Valve Enclosure {toc}

+### The pre-action or deluge valve, its trim, its supply piping, the priming supply, and the supervisory gas source shall be located in an enclosure that is maintained at not less than the temperature indicated in the datasheet.

+```datasheet

+label: Valve Enclosure Minimum Temperature

+type: range

+unit: °F

+min: 40

+max: 60

+setpoints: [40, 45, 50, 55, 60]

+default: 40

+```

+### The means of heating the valve enclosure shall be as indicated in the datasheet.

+```datasheet

+label: Valve Enclosure Heating

+type: select

+options:

+ - "Heated room of the building"

+ - "Dedicated electric unit heater in the valve enclosure"

+ - "Hydronic or steam unit heater in the valve enclosure"

+ - "Listed insulated and heated valve enclosure"

+```

+### The heating provision shall maintain the datasheet temperature at the valve with the outdoor temperature at [[parameter: site-ambient-temperature-minimum]] and with the protected space at its lowest operating temperature.

+### The water side of the valve, the diaphragm chamber, the priming line, and the pilot lines are wet, so the valve is a wet component that has to live in heated space even though everything downstream of it is dry, and a deluge valve serving an outdoor hazard or a pre-action valve serving a freezer is the one most often found in a shed that the building's heating never reached. {note}

+### The valve enclosure shall provide clearance to operate every trim valve, read every gauge, service the supervisory gas source, reach the releasing solenoid and the manual emergency release, and remove the valve cover for internal inspection.

+### The valve enclosure shall be provided with a floor drain or an exterior discharge sized for the main drain flow.

+### The location of each valve enclosure shall be as indicated on [[drawing: the fire protection plans]].

+# Supervisory Gas Supply {toc}

+## Supervisory Gas Source {toc}

+### Requirements in this section apply to pre-action systems, whose piping is held under supervisory gas; a deluge system is open to atmosphere and has no supervisory gas.

+### The supervisory gas source for each pre-action system shall be as indicated in the datasheet.

+```datasheet

+label: Supervisory Gas Source

+type: select

+options:

+ - "Dedicated riser-mounted air compressor"

+ - "Dedicated tank-mounted air compressor"

+ - "Plant compressed air system through an air maintenance device"

+ - "Membrane nitrogen generator"

+ - "Pressure-swing adsorption nitrogen generator"

+ - "Nitrogen cylinders through a pressure regulator"

+ - "Not applicable, deluge systems only"

+```

+### The supervisory gas is either air or nitrogen, and the source selected fixes which. Air is what a compressor supplies and what oxidizes the pipe interior at every place water stands; nitrogen displaces that oxygen and is supplied by a generator that separates it from compressed air on site or by cylinders that are exchanged. Where the piping is to hold water rarely and be drained after every event, the corrosion nitrogen prevents is slower to arrive and air is the simpler supply; where the piping is expected to serve its full life with a supply that stands water at low points, or where the pipe interior is uncoated black steel, nitrogen removes the oxygen that drives the corrosion FM Global Data Sheet 2-1 describes, at the cost of a generator, a purge, and a purity to supervise. {note}

+### The supervisory pressure a pre-action valve needs is set by the valve, not by the water supply, so a pre-action system is held at a fraction of the supervisory pressure a dry-pipe valve on the same supply would need, and a source sized for a dry-pipe system is larger than a pre-action system uses. {note}

+### Where the supervisory gas source is a plant compressed air system, the connection to each pre-action system shall pass through a listed air maintenance device and a check valve, and the plant air shall be dried and filtered before it enters the device.

+### Where the supervisory gas source serves more than one pre-action system, each system shall be connected through its own listed air maintenance device and check valve, so that a release or a trip on one system does not depressurize the others.

+### The supervisory gas supply shall be provided with a listed relief valve, set not higher than the pressure rating of the system components, in accordance with NFPA 13.

+### The compressor or nitrogen generator shall be supplied from a dedicated branch circuit identified at the panelboard as serving the fire sprinkler supervisory gas supply, and the circuit shall comply with NFPA 70.

+### Where the supervisory gas source is a nitrogen generator, the generator shall be listed for the purpose, and the feed compressor, filtration, and separation module shall be furnished as the listed assembly.

+## Supervisory Gas Pressure {toc}

+### The normal supervisory gas pressure of each pre-action system shall be as indicated in the datasheet.

+```datasheet

+label: Supervisory Gas Pressure

+type: range

+unit: psi

+derived: "the supervisory pressure range the valve manufacturer publishes for the selected valve, system type, and release actuation, set at the value within that range that the low-pressure setpoint and the air maintenance device require"

+min: 5

+max: 60

+setpoints: [5, 7, 10, 13, 15, 20, 25, 30, 40, 50, 60]

+default: derived

+```

+### A pre-action valve is not held closed by the supervisory gas, so the pressure is chosen for supervision rather than for a differential: high enough that the low-pressure switch has a margin to operate above the pressure a slow leak settles at, and low enough that an open sprinkler bleeds the system to the setpoint quickly. Every psi above what the margin needs is a psi that delays the low-pressure signal on a double-interlock system, and the delay is added to the water delivery time. {note}

+### The low-pressure supervisory switch setpoint of each pre-action system shall be as indicated in the datasheet.

+```datasheet

+label: Low-Pressure Supervisory Setpoint

+type: range

+unit: psi

+derived: "the supervisory gas pressure and the low-pressure setpoint the valve manufacturer publishes for the selected valve and system type, set below the normal pressure by the margin the manufacturer publishes"

+min: 3

+max: 50

+setpoints: [3, 5, 7, 10, 15, 20, 25, 30, 40, 50]

+default: derived

+```

+### The supervisory pressure shall not be raised above the datasheet value to compensate for leakage.

+### The air supply shall restore a pre-action system from atmospheric pressure to its normal supervisory pressure within the time indicated in the datasheet.

+```datasheet

+label: Air Supply Restoration Time

+type: range

+unit: minutes

+min: 10

+max: 30

+setpoints: [10, 15, 20, 30]

+default: 30

+```

+### NFPA 13 requires the automatic supply to restore normal pressure within 30 minutes, and the air maintenance device limits the fill rate so that a leak large enough to operate the low-pressure switch is not masked by a supply that keeps up with it. A shorter time returns the system to service sooner after a test, at the cost of a larger compressor and no faster fill on a system that leaks. {note}

+### The compressor or the feed compressor of a nitrogen generator shall draw its intake from the heated valve enclosure or from another heated interior space, and where any part of the pre-action piping serves a space held at or below 32°F the supervisory gas shall be dried to a pressure dew point below the lowest temperature of that space.

+## Nitrogen Supply {toc}

+### Requirements in this article apply where the supervisory gas is nitrogen.

+### The nitrogen purity maintained in the system shall be not less than the value indicated in the datasheet, measured at the remote end of the system.

+```datasheet

+label: Nitrogen Purity at the System

+type: range

+unit: '%'

+min: 95

+max: 99

+setpoints: [95, 98, 99]

+default: 98

+```

+### The corrosion credit NFPA 13 and FM Global Data Sheet 2-1 give a nitrogen-supervised system rests on the oxygen concentration being held low enough that the pipe interior does not corrode at a rate that matters, and 98 percent nitrogen is the purity those documents describe. A higher purity costs generator capacity and purge time and buys a smaller further reduction in oxygen. {note}

+### Each nitrogen-supervised system shall be provided with a purge provision at its remote end, and the system shall be purged after the air leakage test and after every subsequent release, trip test, or drain-down until the purity at the remote end reaches the datasheet value, and the purity shall be recorded.

+### Where nitrogen is the supervisory gas, the low-pressure supervisory switch, the relief valve, the air maintenance device, and the gauges shall be as required for air under this standard.

+## Supervisory Signals {toc}

+### Each pre-action system shall be provided with a listed low-pressure supervisory switch that transmits a supervisory signal to the releasing control unit and to the building fire alarm system when the supervisory gas pressure falls to the setpoint, in accordance with NFPA 72 and [[sync/fire-alarm-systems]].

+### The piping of a pre-action system with more than 20 sprinklers, and the detection devices of every pre-action and deluge system, shall be automatically supervised, in accordance with NFPA 13.

+### The additional supervisory signals provided for each system shall be as indicated in the datasheet.

+```datasheet

+label: Additional Supervisory Signals

+type: checkbox

+options:

+ - "High supervisory gas pressure"

+ - "Valve enclosure low temperature"

+ - "Air compressor fault or excessive run time"

+ - "Nitrogen generator trouble or low purity"

+ - "Priming water level low"

+ - "Pilot line low pressure"

+```

+### Each supervisory signal shall be received at the building fire alarm system as a distinct supervisory point identified with the system it belongs to, in accordance with [[sync/fire-alarm-systems]].

+### A high-pressure signal reports a failed regulator or a stuck air maintenance device, which delays the low-pressure signal a double-interlock release waits for; a run-time signal reports a leak by the compressor working to keep up with it; a low-temperature signal at the valve enclosure reports the heating failure that freezes the priming line before the valve fails; and a priming level signal reports a diaphragm chamber that has lost the water that holds the valve closed. {note}

+# Water Delivery Time and System Volume {toc}

+## The volume of each double-interlock pre-action system shall be calculated from the working drawings and stated in the action submittal.

+## Water shall reach the inspector's test connection at the most remote point of each double-interlock pre-action system within the time indicated in the datasheet, measured from the operation of the initiating device that completes the interlock with the system at its normal supervisory pressure.

+```datasheet

+label: Water Delivery Time Limit

+type: range

+unit: s

+derived: "the hazard classification selected for the protected area under the sprinkler family standard and the calculated system volume, applied to the water delivery provisions NFPA 13 extends from dry-pipe systems to double-interlock pre-action systems"

+min: 15

+max: 60

+setpoints: [15, 40, 45, 50, 60]

+default: derived

+```

+## NFPA 13 applies the dry-pipe water delivery provisions to a double-interlock system because water is not in the pipe when the first sprinkler opens: the small-system exemption, the delivery table by hazard, and the calculation and test for a larger system all apply as they apply to a dry-pipe system. A non-interlock or single-interlock system fills on detection and has no delivery time requirement; a deluge system has no closed sprinklers to wait for and its delivery is proven by the time to water at the most remote device in the trip test. {note}

+## Where the volume of a double-interlock system exceeds the exemption NFPA 13 provides, the delivery time shall be demonstrated by a calculation using a method acceptable to the Authority Having Jurisdiction, and the calculation shall assume the supervisory pressure the system will actually be held at and the time the releasing logic takes to operate the valve.

+## The delivery time of a double-interlock system includes the time for the open sprinkler to bleed the supervisory gas to the low-pressure setpoint and the time for the releasing control unit to act on the signal, neither of which exists on a dry-pipe system, and a calculation that starts its clock at the valve rather than at the sprinkler understates the time the test will measure. {note}

+## Where the calculated delivery time of a double-interlock system exceeds the datasheet limit, the system shall be subdivided, the supervisory pressure shall be lowered within the manufacturer's range, or a listed quick-opening device shall be provided where the valve listing permits one, until the limit is met.

+## The calculated delivery time shall be confirmed by the trip test required under Testing, and the tested time shall govern acceptance.

+# Deluge Discharge Devices and Zones {toc}

+## Requirements in this section apply to deluge systems.

+## The open discharge devices on each deluge system shall be as indicated in the datasheet.

+```datasheet

+label: Deluge Discharge Devices

+type: select

+options:

+ - "Open standard spray sprinklers"

+ - "Open extended coverage sprinklers"

+ - "Open directional spray nozzles"

+ - "Open window sprinklers for a water curtain"

+```

+## An open sprinkler is a listed sprinkler with its operating element removed and discharges the pattern its deflector produces at the spacing NFPA 13 sets for that sprinkler type; a directional spray nozzle discharges a listed cone or fan at the angle and distance its listing states, and is aimed at a surface rather than spread over an area; and a window sprinkler wets a glazed or exposed surface as a curtain. The hazard decides which: a floor area takes sprinklers, a piece of equipment takes nozzles aimed at it, and an exposure takes a curtain. {note}

+## Open sprinklers shall be spaced, positioned, and cleared of obstructions in accordance with NFPA 13 for the sprinkler type, the hazard classification, and the ceiling construction, as though they were closed sprinklers of the same type.

+## Directional spray nozzles shall be selected, oriented, and spaced in accordance with their listing and, where the design is a water spray design, in accordance with NFPA 15, and the orientation and aiming point of each nozzle shall be as indicated on [[drawing: the deluge zone layout]].

+## The type, orifice, and orientation of the discharge device at each location shall be as indicated on [[drawing: the deluge zone layout]].

+## The extent of each deluge zone shall be as indicated on [[drawing: the fire protection riser diagram]].

+## The hydraulic design of each deluge zone shall cover every discharge device on the zone at the design density, with no remote area, in accordance with NFPA 13.

+## The number of deluge zones assumed to operate simultaneously in the hydraulic design shall be as indicated in the datasheet.

+```datasheet

+label: Deluge Zones Operating Simultaneously

+type: range

+unit: zones

+drawing_ref: "the fire protection riser diagram"

+min: 1

+max: 4

+setpoints: [1, 2, 3, 4]

+default: deferred

+```

+## A fire that crosses a zone boundary opens the adjacent zone, and a hangar or a conveyor is zoned so that the water supply carries the zones a fire can reach together; NFPA 409 and the hazard-specific standards state the adjacent-zone assumption where one applies, and the water supply and fire pump are sized under [[sync/wet-pipe-fire-sprinkler-systems]] and [[sync/fire-pumps]] for the zones the datasheet assumes. {note}

+## Where a hazard-specific standard, including NFPA 409 for an aircraft hangar, governs the deluge design, its zoning, density, and simultaneous-operation provisions shall govern over the datasheet value.

+## Deluge piping shall be arranged to drain completely to the main drain or to auxiliary drains after every operation and test.

+## Open discharge devices shall be provided with a strainer at the valve where the listing or NFPA 13 requires one for the orifice size installed, and each nozzle with an orifice smaller than the listing's unstrained minimum shall be individually strained.

+## An open nozzle is not opened by heat, so it is not flushed by a fire; the scale that a hydrostatic test moves down the pipe arrives at a small nozzle orifice and stays there, and the strainer at the valve is what keeps the first trip test from discharging a plug into the nozzle. {note}

+# Sprinklers and Piping Downstream of the Valve {toc}

+## Sprinklers on pre-action piping shall be of the types NFPA 13 permits on a pre-action system, and a standard pendent sprinkler shall be installed on pre-action piping only where NFPA 13 permits it for the system type and where the sprinkler and the branch line serving it are in heated space.

+## The sprinkler type, orifice, temperature rating, thermal response, and finish for each area shall be as selected under [[sync/wet-pipe-fire-sprinkler-systems]].

+## Where a heat detector precedes the sprinklers under Releasing Detection, the sprinkler temperature rating selected under [[sync/wet-pipe-fire-sprinkler-systems]] shall be higher than the detector rating.

+## The barrel length of each dry pendent and dry sidewall sprinkler shall be as indicated on [[drawing: the sprinkler schedule]].

+## Pre-action piping shall be pipe, fittings, and joints selected under [[sync/fire-protection-piping]] for dry service, assembled for gas-tightness as well as water-tightness, with the interior corrosion protection selected under [[sync/dry-pipe-fire-sprinkler-systems]].

+## A gridded pipe arrangement shall not be used on a pre-action or deluge system, which NFPA 13 prohibits.

+## Pipe on a deluge system shall be selected under [[sync/fire-protection-piping]] for service that is open to atmosphere and wetted at every operation, and its interior corrosion protection shall be selected under [[sync/dry-pipe-fire-sprinkler-systems]] as for air-supervised dry piping.

+## Deluge piping cannot be nitrogen-supervised because it is open at every nozzle, so the corrosion options available to it are the pipe interior itself and complete drainage after every wetting. {note}

+# Waterflow Alarm {toc}

+## The waterflow alarm for each pre-action or deluge system shall be initiated by a listed alarm pressure switch connected to the alarm outlet of the valve, and the switch shall transmit a waterflow signal to the building fire alarm system in accordance with NFPA 72 and [[sync/fire-alarm-systems]].

+## Vane-type waterflow switches shall not be installed in pre-action or deluge piping.

+## The pressure switch on the alarm outlet sees supply pressure the moment the valve opens, so the waterflow alarm is transmitted when water enters the piping rather than when it reaches a sprinkler, and on a pre-action system that fills on detection the alarm follows the detection by the time the valve takes to open. A vane in dry piping is struck by the slug of gas and water the valve drives through it, which NFPA 13 prohibits because the vane and the alarm both fail under it. {note}

+## Where a water motor alarm is selected under the alarm policy of [[sync/wet-pipe-fire-sprinkler-systems]], the alarm line from the valve to the gong shall be arranged to drain and shall not hold water in unheated space.

+# Installation {toc}

+## Pre-action and deluge piping shall be installed to the pitch, drainage, and auxiliary drain arrangement reviewed under [[sync/dry-pipe-fire-sprinkler-systems]], and a deviation that creates a trapped section shall be reported to the Engineer of Record before the section is hung.

+## Open ends of pre-action and deluge piping shall be capped whenever work stops, and the piping shall be kept free of cutting debris, thread chips, and construction material until it is closed.

+## The trim of a pre-action or deluge valve, the releasing solenoid, and the air maintenance device pass gas and water through small orifices that a chip of pipe scale can close, and an open nozzle on a deluge system is an orifice with nothing to protect it; the first trip after construction is when the debris that entered during construction arrives at those orifices. {note}

+## After the hydrostatic test required under [[sync/wet-pipe-fire-sprinkler-systems]], the piping shall be drained at the main drain and at every auxiliary drain before a pre-action system is placed under supervisory gas or a deluge system is placed in service, and each auxiliary drain shall be operated and confirmed clear as part of that drain-down.

+## Open discharge devices on a deluge system shall be installed after the piping has been flushed under [[sync/wet-pipe-fire-sprinkler-systems]], and shall be protected from paint, overspray, and debris until the finish trades have completed work in the area.

+## The valve shall be installed with its trim oriented as the listing requires and with the gauges, the priming connection, the releasing solenoid, the manual emergency release, and the chamber drain reachable from the floor of the valve enclosure.

+## Detection devices shall be installed at the locations and spacing of the reviewed detection layout, and a detector relocated to clear another trade's work shall be relocated within its listed spacing and reported on the as-built layout.

+## The releasing circuits, the initiating device circuits, and the pilot lines shall be installed by the trade responsible for the releasing side of the system under [[sync/fire-alarm-systems]], and the sprinkler Contractor shall provide that trade with the location and type of every solenoid, supervisory switch, and alarm switch before the releasing circuits are routed.

+## Pilot lines shall be installed with the pitch, the supports, and the protection against mechanical damage and freezing that the valve manufacturer's listing requires, and shall be routed as indicated on [[drawing: the fire protection plans]].

+# Testing {toc}

+## Air Leakage Test {toc}

+### In addition to the hydrostatic test, each pre-action system shall be tested with air or nitrogen at 40 psi for 24 hours, and the pressure loss over the 24 hours shall not exceed 1.5 psi, in accordance with NFPA 13.

+### The pressure and the ambient temperature at the piping shall be recorded at the start and at the end of the 24 hours, and a pressure change consistent with the temperature change shall not be counted as leakage.

+### A pre-action system leaks gas through joints that held water, and a joint that leaks gas on a double-interlock system is a joint that lowers the supervisory pressure toward the interlock setpoint without an open sprinkler. The 24-hour test is the one that finds the joints the compressor would otherwise spend its life keeping up with. {note}

+### Leaks shall be located with a leak-detection solution or an ultrasonic detector, and the joint shall be remade rather than sealed from the outside.

+### A system that fails the air leakage test shall be retested in full after the repair, and the cost of the repair and of every retest shall be borne by the Contractor.

+## Trip Test {toc}

+### Each pre-action or deluge valve shall be trip tested at acceptance by the method indicated in the datasheet, with the control valve open as the method requires, the system at its normal supervisory pressure where it is gas-supervised, and the release initiated by operating the detection devices that satisfy the initiating logic.

+```datasheet

+label: Acceptance Trip Test Method

+type: radio

+options:

+ - "Full-flow trip test, water flowed to the inspector's test connection or from every open device"

+ - "Full-flow trip test, discharge diverted through a test header"

+ - "Trip test with the control valve partially open, discharge through the main drain"

+ - "Releasing logic and solenoid operation test without water flow"

+default: "Full-flow trip test, water flowed to the inspector's test connection or from every open device"

+```

+### NFPA 13 requires a full-flow trip test at acceptance, and the alternatives exist for the property the water would ruin: a test header takes the full flow of a deluge zone to a drain through a valved connection while the nozzles stay dry; a partially open control valve proves the valve trips and the alarm transmits while limiting the water to what the main drain carries; and a test without water flow proves the detection, the logic, and the solenoid on a system whose discharge cannot be accepted even through a drain. Each step away from full flow leaves something unproven, and the record states what. {note}

+### A trip test method other than the full-flow test shall be used only where the Engineer of Record has determined that a full-flow discharge would damage the protected property or its contents and the Authority Having Jurisdiction has accepted the method in writing.

+### Where the method selected does not flow water to the most remote discharge device, the Contractor shall demonstrate by the hydraulic calculation and by a flow through the main drain or the test header that the supply delivers the design flow and pressure at the valve, and the record shall state that the delivery to the devices was not tested.

+### On a double-interlock system, the trip test shall be initiated by operating the detection and by opening the inspector's test valve to bleed the supervisory pressure to the low-pressure setpoint, and the test shall record the time from each event to the release.

+### On a double-interlock system, the test shall also confirm that operating the detection alone does not release the valve and that bleeding the supervisory pressure alone does not release the valve.

+### The double interlock is proven by what does not happen. A valve that opens on the detection alone is a single-interlock valve in a freezer, and no test that only confirms the release would have found it. {note}

+### Where a double-interlock system is subject to the water delivery time requirement, the time to water at the inspector's test connection shall not exceed the datasheet limit.

+### Where the tested delivery time exceeds the limit, the Contractor shall correct the cause and repeat the test, and the cost of the correction and the retest shall be borne by the Contractor.

+### The manual emergency release at the valve and each remote manual release station shall be operated as part of the trip test, and the valve shall open on each.

+### The trip test shall be witnessed by the Authority Having Jurisdiction where the Authority requires it, and the Contractor shall schedule the test with the Authority not less than five working days before it is run.

+### After the trip test the system shall be drained at the main drain and at every auxiliary drain, the diaphragm chamber or intermediate chamber shall be drained and confirmed clear, the valve shall be reset in accordance with the manufacturer's instructions, the priming water shall be restored where the listing requires it, and a pre-action system shall be restored to its normal supervisory pressure and, where nitrogen is the supervisory gas, purged to the datasheet purity.

+## Releasing Sequence Tests {toc}

+### Every row of the releasing matrix shall be tested by producing its initiating condition, and the operation or non-operation of every output the row assigns shall be recorded against the matrix.

+### Each detection device shall be tested by the method NFPA 72 assigns to its type, and the receipt of its signal at the releasing control unit and the alarm at the building fire alarm system shall be recorded.

+### Where cross-zoned or two-detector logic is selected, the test shall confirm that a single detection produces the alarm and the detection-stage functions without a release, and that the second detection produces the release.

+### Where a release delay is provided, the delay shall be timed from the satisfied logic to the releasing output and shall match the datasheet value, and the pre-discharge alarm shall be confirmed to sound for the delay.

+### Where an abort function is provided, the test shall confirm that the abort holds the release only while held operated, and that the manual emergency release and the remote manual release station open the valve with the abort held.

+### Each auxiliary function shall be tested by producing the stage that operates it and confirming the operation of the device or system it controls, with the trade responsible for that system present.

+### The releasing circuit supervision shall be tested by opening the circuit at the solenoid and confirming the trouble signal at the releasing control unit and at the building fire alarm system, and the supervised disconnect shall be tested by operating it.

+### The secondary power of the releasing control unit shall be tested by disconnecting the primary supply and operating a release on secondary power.

+## Supervisory Device Tests {toc}

+### The alarm pressure switch shall be tested during the trip test by confirming that the building fire alarm system received the waterflow signal, and the time from the valve opening to the signal shall be recorded.

+### The low-pressure supervisory switch of each pre-action system shall be tested by bleeding gas from the system at the inspector's test connection until the switch operates, and the pressure at which it operated shall be recorded and compared with the datasheet setpoint.

+### Each additional supervisory signal indicated in the datasheet shall be tested by producing its condition, and the receipt of each signal at the building fire alarm system shall be recorded.

+### The air supply of each pre-action system shall be tested by depressurizing the system to atmosphere and timing the restoration to normal supervisory pressure, and the time shall not exceed the datasheet restoration time.

+# Delivery, Storage, and Handling {toc}

+## The releasing control unit, the detection devices, and the releasing solenoids shall be delivered in their original packaging and stored indoors in a conditioned space, protected from dust, moisture, and impact, until the space they serve is ready to receive them.

+## Open discharge devices for a deluge system shall be stored in their original packaging with the orifice protected, and a device whose orifice or deflector has been struck or fouled shall not be installed.

+## Sprinklers, pipe, fittings, valves, and the supervisory gas equipment shall be delivered, stored, and handled under [[sync/wet-pipe-fire-sprinkler-systems]] and [[sync/fire-protection-piping]].

+# Spare Parts {toc}

+## The Contractor shall deliver the spare parts indicated in the datasheet to the Owner before the system is accepted, and shall obtain a signed receipt for them.

+```datasheet

+label: Pre-Action and Deluge Spare Parts to Be Furnished

+type: checkbox

+options:

+ - "Releasing solenoid of each type installed"

+ - "Valve diaphragm or clapper seat kit for each valve model installed"

+ - "Detectors of each type installed"

+ - "Open sprinklers or nozzles of each type installed on a deluge system"

+ - "Air compressor intake filter element"

+ - "Nitrogen generator filter elements for one service interval"

+```

+## Spare parts shall be the same make and model as the installed items, delivered in their original packaging, and labeled with the system they serve.

+## A failed solenoid or a failed detector on a released zone impairs the whole system until it is replaced, and the parts that keep a releasing system in service are the ones a local supply house is least likely to stock. {note}

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