+---
+title: Clean Agent Fire Suppression Systems
+category: Fire Protection
+toc_depth: 3
+description: >
+ When to use: Engineered and pre-engineered gaseous total-flooding clean-agent fire extinguishing systems that protect high-value, mission-critical, or water-sensitive enclosures by discharging an electrically non-conductive, residue-free agent that suppresses fire without wetting or contaminating the protected contents. Covers both families of agent recognized by NFPA 2001 — halocarbon agents (such as HFC-227ea and the fluoroketone FK-5-1-12), which extinguish primarily by heat absorption, and inert-gas agents (such as IG-541, IG-55, and IG-100), which extinguish by reducing the oxygen concentration below that needed to support combustion. Addresses agent selection, design concentration and the NOAEL/LOAEL occupant-safety margins, cross-zoned detection and the releasing control unit, manual release and abort, agent storage containers and distribution piping and nozzles, discharge time and minimum hold (soak) time, enclosure integrity verified by a door-fan (enclosure-integrity) test, pressure-relief venting of the enclosure, and acceptance testing and commissioning. Typical protected spaces include data centers and server rooms, telecommunications and equipment rooms, control rooms, electrical and switchgear rooms, and museum, library, and archival storage.
+ Not intended for: Ordinary occupancies and general building areas where water-based suppression is appropriate and required — see [[sync/wet-pipe-fire-sprinkler-systems]] and, for unheated or high-value/water-sensitive spaces protected by a supervised charged-on-detection system, [[sync/pre-action-and-deluge-sprinkler-systems]]. Not for water-mist systems; carbon-dioxide total-flooding or local-application systems (which present a life-safety asphyxiation hazard governed by NFPA 12); kitchen-hood wet-chemical systems; dry-chemical systems; condensed or pyrotechnic aerosol systems; explosion suppression; or outdoor, open, or non-enclosable hazards that cannot hold an agent concentration. The fire detection and alarm system that signals occupants and transmits to the supervising station is covered in [[sync/fire-alarm-systems]]; this standard governs only the detection and releasing function dedicated to agent discharge.
+---
+
+# Scope
+
+This standard covers the design documentation, agent selection, equipment, installation, testing, and commissioning of gaseous total-flooding clean-agent fire extinguishing systems installed to protect an enclosed volume by establishing and holding a uniform extinguishing concentration of a clean agent throughout that volume. A clean agent is defined by NFPA 2001, Standard on Clean Agent Fire Extinguishing Systems, as an electrically non-conductive, volatile or gaseous fire extinguishant that does not leave a residue upon evaporation. The defining advantage of these systems is that they suppress fire without water, foam, or powder, so they protect energized electronic equipment, irreplaceable records, and sensitive contents that water-based suppression would destroy.
+
+A total-flooding clean-agent system does not act on a single burning object the way a sprinkler discharges onto a fire; it floods the entire protected enclosure to a design concentration and then relies on the enclosure to hold that concentration long enough for the fire to be fully extinguished and for hot surfaces to cool below the point of re-ignition. For this reason the integrity of the enclosure is as much a part of the system as the agent and the hardware. An enclosure that leaks the agent faster than the design hold time allows is a defective installation even if every container, pipe, and nozzle is perfect. The enclosure-integrity (door-fan) test required by NFPA 2001 is therefore a mandatory part of the work under this standard, not an optional extra.
+
+The scope extends from the agent storage containers and their actuation devices, through the discharge piping and nozzles, to the protected enclosure and its pressure-relief venting; and it includes the dedicated detection and releasing control unit, the cross-zoned detection, the manual release and abort stations, the discharge and pre-discharge alarms and warning signs, and the interlocks to the building HVAC and dampers that condition the enclosure for a successful discharge. All work shall comply with NFPA 2001 for the clean-agent system itself, with NFPA 72, National Fire Alarm and Signaling Code, for the detection and releasing service that actuates it, and with NFPA 70, National Electrical Code, for the wiring. The agent shall be one that is acceptable for total-flooding use under the U.S. EPA Significant New Alternatives Policy (SNAP) program for the occupancy condition involved.
+
+This standard is agnostic as to the specific agent and manufacturer. Agents are described throughout by their NFPA 2001 generic designation (for example HFC-227ea, FK-5-1-12, IG-541, IG-55, IG-100) and never by trademarked brand name. The designer selects the agent and the listed system that delivers it; this standard establishes the performance, safety, and quality requirements that selection shall satisfy.
+
+# Referenced Standards
+
+Design, equipment, installation, and testing shall comply with the current adopted editions of the following standards and codes. Where the contract documents, the adopted building or fire code, a listed-system manufacturer's design and installation manual, or a referenced standard conflict, the more stringent requirement shall govern unless the Engineer of Record directs otherwise in writing. A clean-agent system is a listed assembly: the listed-system design and installation manual establishes container fill ranges, pipe limits, and nozzle coverage that are conditions of the listing and shall not be exceeded even where this standard or the drawings would otherwise permit it.
+
+| Standard | Title |
+|----------|-------|
+| NFPA 2001 | Standard on Clean Agent Fire Extinguishing Systems |
+| NFPA 72 | National Fire Alarm and Signaling Code (detection and releasing service) |
+| NFPA 70 | National Electrical Code |
+| NFPA 70B | Standard for Electrical Equipment Maintenance (where electrical rooms are protected) |
+| NFPA 75 | Standard for the Fire Protection of Information Technology Equipment |
+| NFPA 76 | Standard for the Fire Protection of Telecommunications Facilities |
+| NFPA 12 | Standard on Carbon Dioxide Extinguishing Systems (referenced for distinction; CO2 is outside this scope) |
+| UL 2166 | Standard for Halocarbon Clean Agent Extinguishing System Units |
+| UL 2127 | Standard for Inert Gas Clean Agent Extinguishing System Units |
+| UL 864 | Standard for Control Units and Accessories for Fire Alarm Systems (releasing service) |
+| UL 268 | Standard for Smoke Detectors for Fire Alarm Systems |
+| ISO 14520 | Gaseous Fire-Extinguishing Systems — Physical Properties and System Design |
+| FM Approval Standards (3500-series) | Approval standards for clean-agent extinguishing systems |
+| EPA SNAP | U.S. EPA Significant New Alternatives Policy program (agent acceptability) |
+| ASME Boiler and Pressure Vessel Code, Sec. VIII | Rules for the construction of pressure vessels (agent storage containers) |
+| DOT 49 CFR | Transportation of agent containers as compressed gas / hazardous materials |
+| IBC | International Building Code |
+| IFC | International Fire Code |
+
+# Submittals
+
+## Action Submittals
+
+The Contractor shall submit the following for the Engineer of Record's review and the Authority Having Jurisdiction's approval before any agent containers are procured or any portion of the system is installed. Clean-agent submittals are engineering documents that the AHJ uses as the primary basis for plan review; the calculations and the enclosure analysis are the heart of the submittal and shall be complete, sealed where required by state law, and internally coordinated before the package is submitted.
+
+- Working drawings showing the protected enclosure(s), the agent storage location, the routing and size of all discharge piping, the type and location of every nozzle, the location of every detector, manual release, abort station, alarm, and warning sign, and the location of the releasing control unit
+- Design concentration calculations establishing the minimum design concentration for the agent and the hazard (flooding factor, the volume of the enclosure, the design temperature, and the resulting agent quantity), with the basis (Class A surface fire, Class B fuel, or energized-equipment design factor) clearly stated and referenced to NFPA 2001
+- Flow (hydraulic) calculations from the listed-system manufacturer's design software, demonstrating that the piping network delivers the required agent quantity to each nozzle and reaches 95 percent of the minimum design concentration within the maximum discharge time permitted by NFPA 2001 for the agent family
+- Occupant-safety analysis stating, for the agent and design concentration selected, the NOAEL and LOAEL (for halocarbon agents) or the resulting minimum oxygen concentration (for inert-gas agents), the occupancy classification of the protected space (normally occupied or normally unoccupied), and the maximum permitted occupant exposure time, in accordance with NFPA 2001
+- An enclosure-integrity analysis predicting the agent retention (hold) time for the as-designed enclosure, identifying all known and suspected leakage paths, and committing to a door-fan test at acceptance to verify the predicted hold time
+- Sequence of operations (matrix) showing every detection input (by zone), the cross-zoning logic, the pre-discharge alarm, the time delay, the abort logic, the discharge output, and every interlock and ancillary function (HVAC and fan shutdown, damper closure, door closure/holders, power shutdown where applicable)
+- Battery (secondary-power) calculations for the releasing control unit per NFPA 72, showing standby and alarm current and the required amp-hour capacity with the code-required margin
+- Product data and listing documentation for the agent, the storage containers and valves, the discharge nozzles, the releasing control unit (UL 864 listed for releasing service), the detectors, and the manual release and abort stations, including the UL 2166 (halocarbon) or UL 2127 (inert-gas) system listing and the EPA SNAP acceptability of the agent for the occupancy condition
+
+```datasheet
+label: Action Submittals Required
+type: checkbox
+options:
+ - "Working drawings (enclosure, piping, nozzles, devices, control unit)"
+ - "Design concentration calculations"
+ - "Flow (hydraulic) calculations from listed design software"
+ - "Occupant-safety analysis (NOAEL/LOAEL or minimum O2)"
+ - "Enclosure-integrity analysis and committed hold time"
+ - "Sequence of operations matrix"
+ - "Releasing control unit battery calculations (NFPA 72)"
+ - "Product data and listing documentation (UL 2166 / UL 2127, EPA SNAP)"
+default: "Design concentration calculations"
+```
+
+## Closeout Submittals
+
+The following shall be submitted at substantial completion, before the system is placed in service and accepted.
+
+- Signed acceptance test report documenting the detection, releasing, alarm, abort, and interlock functions verified per NFPA 2001 and NFPA 72, including the verified pre-discharge delay and the verified ancillary shutdowns
+- The enclosure-integrity (door-fan) test report, recording the measured enclosure leakage, the calculated agent retention (hold) time at the design concentration descending to the protected height, and the pass/fail determination against the required minimum hold time
+- As-built working drawings reflecting actual piping routing and sizes, nozzle locations, device locations, and the final container fill weights or pressures
+- The releasing control unit programming record, including the cross-zoning logic, the time delay, and the abort behavior as commissioned
+- Operation and maintenance data, including the agent type and quantity per container, the container recharge and hydrostatic-retest schedule, the detector and control-unit inspection and test intervals per NFPA 2001 and NFPA 72, and the date by which the next enclosure-integrity test is recommended
+- Warning and instruction signs verification (pre-discharge, discharge, abort, and lockout/disable signage installed at the required locations)
+
+```datasheet
+label: Closeout Submittals Required
+type: checkbox
+options:
+ - "Acceptance test report (detection, release, alarm, abort, interlocks)"
+ - "Enclosure-integrity (door-fan) test report with hold time"
+ - "As-built working drawings with final fill weights/pressures"
+ - "Releasing control unit programming record"
+ - "Operation and maintenance data"
+ - "Warning and instruction signage verification"
+default: "Enclosure-integrity (door-fan) test report with hold time"
+```
+
+# Quality Assurance
+
+## Designer and Installer Qualifications
+
+The clean-agent system shall be designed, installed, and commissioned by personnel trained and certified by the manufacturer of the listed system being installed, in accordance with NFPA 2001. The listed clean-agent system is an engineered assembly whose flow calculations, container fill ranges, pipe-length and fitting limits, and nozzle coverage are valid only when the system is designed using the manufacturer's listed design software and installed within the limits of the manufacturer's design and installation manual. The Contractor shall hold the licensing required by the state and local jurisdiction for fire suppression system work, and the individual preparing the design shall hold the qualifications the AHJ requires (commonly a licensed fire protection engineer or a NICET-certified designer in special-hazards or clean-agent systems at the level required by state law).
+
+```datasheet
+label: Designer / Installer Qualification Basis
+type: radio
+options:
+ - "Manufacturer-certified designer/installer for the listed system + state license"
+ - "Licensed fire protection engineer (special hazards) + manufacturer-certified installer"
+ - "NICET special-hazards / clean-agent certification + state license"
+ - "As accepted by AHJ — submit documentation for review"
+default: "Manufacturer-certified designer/installer for the listed system + state license"
+```
+
+## Listing and Approval
+
+The complete clean-agent system shall be a listed system — agent, containers, valves, actuators, nozzles, pipe limits, and the releasing control unit evaluated together — listed to UL 2166 for halocarbon agents or to UL 2127 for inert-gas agents, or to the equivalent ISO 14520 and FM approval where the project requires it. Components shall not be mixed across listings; a nozzle, container valve, or quantity outside the listed system invalidates the flow calculation and the listing. The releasing control unit shall be listed to UL 864 for releasing service. The agent shall be acceptable for total-flooding use under the EPA SNAP program for the occupancy condition (normally occupied or normally unoccupied) involved.
+
+```datasheet
+label: System Listing / Approval Basis
+type: radio
+options:
+ - "UL 2166 (halocarbon) listed system throughout"
+ - "UL 2127 (inert gas) listed system throughout"
+ - "ISO 14520 designed with FM approval"
+ - "UL listing plus FM approval (insurer requirement)"
+default: "UL 2166 (halocarbon) listed system throughout"
+```
+
+## Coordination with Other Trades
+
+The clean-agent Contractor shall coordinate early and continuously with the mechanical, electrical, architectural, and fire alarm trades. The enclosure that holds the agent is built by other trades: every cable penetration, conduit sleeve, raised-floor and ceiling-plenum boundary, door undercut, damper, and duct opening is a potential leakage path that determines whether the system passes its enclosure-integrity test. The Contractor shall identify the enclosure boundary on the working drawings, shall coordinate sealing of all penetrations with the trades that create them, and shall coordinate the shutdown of HVAC and the closure of dampers and doors on discharge with the mechanical and fire alarm contractors. Where the protected space adjoins or sits within an area protected by water-based suppression, the boundary and the interaction shall be coordinated with [[sync/wet-pipe-fire-sprinkler-systems]] or [[sync/pre-action-and-deluge-sprinkler-systems]].
+
+# Environmental and Service Conditions
+
+## Storage and Discharge Temperature
+
+The agent storage containers and the protected enclosure shall be within the temperature range for which the listed system is rated. Halocarbon agents are stored as a liquid under superpressurization with an inert gas (commonly nitrogen); the storage temperature affects the container pressure and the quantity of agent that can be discharged through the piping, and the design temperature of the protected space affects the volume the agent must flood and therefore the required quantity. Inert-gas agents are stored as a high-pressure gas and are likewise temperature sensitive. The minimum design temperature of the enclosure governs the agent quantity, because a colder, denser atmosphere requires more agent to reach the design concentration.
+
+```datasheet
+label: Agent Storage Temperature Range
+type: range
+unit: °F
+options:
+ min: 0
+ max: 130
+ setpoints: [0, 32, 40, 70, 100, 130]
+default: 70
+```
+
+```datasheet
+label: Minimum Enclosure Design Temperature
+type: range
+unit: °F
+options:
+ min: 0
+ max: 100
+ setpoints: [0, 32, 50, 70, 90, 100]
+default: 70
+```
+
+# System Type and Agent Selection
+
+## Total-Flooding Basis
+
+The system shall be a total-flooding system that establishes a uniform agent concentration throughout the protected volume. Local-application clean-agent systems are not within this scope. The protected volume is the gross enclosure volume, including any raised-floor void and ceiling plenum that is part of the protected space and is not otherwise sealed off; where the void or plenum is a separate fire risk (containing power or data cabling), it shall be protected and the agent quantity calculated for it as part of the design.
+
+## Agent Family
+
+The two agent families differ fundamentally in how they extinguish fire, in how much agent is required, in their occupant-safety behavior, and in their discharge and venting requirements, and the choice drives the rest of the design. Halocarbon agents (for example HFC-227ea and the fluoroketone FK-5-1-12) extinguish primarily by absorbing heat from the flame; they are stored as a liquid, require a relatively small storage footprint, flood the space quickly, and are subject to a maximum 10-second discharge time. Inert-gas agents (for example IG-541, a blend of nitrogen, argon, and carbon dioxide; IG-55, a nitrogen-argon blend; and IG-100, nitrogen) extinguish by displacing oxygen and reducing it below the level that supports combustion; they are stored as a high-pressure gas, require a substantially larger bank of cylinders, discharge over a longer 60-second period, and demand careful pressure-relief venting because they add a large gas volume to the enclosure.
+
+```datasheet
+label: Agent Family
+type: radio
+options:
+ - "Halocarbon (heat-absorbing; liquid storage; 10 s discharge)"
+ - "Inert gas (oxygen-reducing; high-pressure gas storage; 60 s discharge)"
+default: "Halocarbon (heat-absorbing; liquid storage; 10 s discharge)"
+```
+
+```datasheet
+label: Clean Agent (NFPA 2001 designation)
+type: select
+drawing_ref: true
+options:
+ - "HFC-227ea (halocarbon)"
+ - "FK-5-1-12 fluoroketone (halocarbon)"
+ - "IG-541 — nitrogen/argon/CO2 (inert gas)"
+ - "IG-55 — nitrogen/argon (inert gas)"
+ - "IG-100 — nitrogen (inert gas)"
+default: "HFC-227ea (halocarbon)"
+```
+
+The agent shall be selected for the hazard, the occupancy condition, the available storage space, the enclosure's ability to tolerate the over- and under-pressure of discharge, and the Owner's environmental objectives. The Contractor shall not substitute a different agent or agent family after design approval without re-running the design concentration, occupant-safety, flow, and enclosure-integrity analyses and resubmitting them, because the agents are not interchangeable.
+
+# Design Concentration and Occupant Safety
+
+## Minimum Design Concentration
+
+The agent quantity shall be calculated to establish at least the minimum design concentration throughout the protected volume at the minimum enclosure design temperature, in accordance with NFPA 2001. The minimum design concentration is derived from the agent's measured extinguishing concentration with a safety factor applied: for Class A surface fires the design concentration is based on the agent's listed Class A extinguishing concentration (established through the UL 2166 or UL 2127 listing program) with the NFPA 2001 safety factor; for Class B fuels it is the cup-burner extinguishing concentration multiplied by the NFPA 2001 safety factor (1.3 for Class B). Where the protected hazard is energized electronic or electrical equipment, an additional design factor is applied per NFPA 2001 to account for the deeper-seated nature of such fires. The design concentration and its basis shall be stated on the calculations and shall be the more demanding where multiple fire types are present.
+
+```datasheet
+label: Design Basis (fire type)
+type: radio
+options:
+ - "Class A surface fire (electronic / records / general contents)"
+ - "Class A energized-equipment hazard (added NFPA 2001 design factor)"
+ - "Class B fuel (cup-burner concentration × 1.3)"
+default: "Class A energized-equipment hazard (added NFPA 2001 design factor)"
+```
+
+```datasheet
+label: Halocarbon Design Concentration
+type: range
+unit: "% by volume"
+drawing_ref: true
+options:
+ min: 5
+ max: 12
+ setpoints: [5, 6, 7, 8, 9, 10, 12]
+default: 7
+```
+
+```datasheet
+label: Inert-Gas Design Concentration
+type: range
+unit: "% by volume"
+drawing_ref: true
+options:
+ min: 34
+ max: 52
+ setpoints: [34, 37, 40, 43, 48, 52]
+default: 40
+```
+
+## Occupancy and the NOAEL / LOAEL Safety Margin
+
+The occupant-safety requirements of NFPA 2001 govern whether the design concentration is acceptable in the protected space and how long occupants may be exposed. For halocarbon agents, safety is expressed by the NOAEL (no observed adverse effect level — the highest concentration at which no adverse physiological effect was observed) and the LOAEL (lowest observed adverse effect level — the lowest concentration at which an adverse effect was observed). In a normally occupied space the design concentration shall not exceed the agent's NOAEL; where it falls between the NOAEL and the LOAEL, occupancy and exposure time are limited per NFPA 2001, and concentrations above the LOAEL are permitted only in normally unoccupied spaces with provisions for occupant egress before discharge. As a reference point, HFC-227ea has a NOAEL of 9.0 percent and a LOAEL of 10.5 percent by volume; the designer shall use the values for the specific agent from the current NFPA 2001 tables.
+
+For inert-gas agents, occupant safety is governed by the resulting oxygen concentration rather than agent toxicity. Reducing oxygen to no lower than about 12 percent (an inert-gas concentration up to roughly 43 percent) permits a limited occupied-exposure period; lower oxygen levels (higher inert-gas concentrations) progressively shorten the permitted exposure and, below about 10 percent oxygen, are permitted only in normally unoccupied spaces with controlled egress, in accordance with NFPA 2001. The egress time built into the pre-discharge sequence shall be reconciled with the permitted exposure time for the design concentration so that occupants can clear the space before a hazardous condition exists.
+
+```datasheet
+label: Space Occupancy Classification
+type: radio
+options:
+ - "Normally occupied — design concentration at or below NOAEL / safe O2 level"
+ - "Normally unoccupied — egress provisions before discharge"
+default: "Normally occupied — design concentration at or below NOAEL / safe O2 level"
+```
+
+```datasheet
+label: Maximum Permitted Occupant Exposure Time
+type: range
+unit: min
+options:
+ min: 0.5
+ max: 5
+ setpoints: [0.5, 1, 3, 5]
+default: 5
+```
+
+# Detection and Releasing Control
+
+## Releasing Control Unit
+
+The system shall be actuated by a dedicated releasing control unit listed to UL 864 for releasing service, in accordance with NFPA 72 and NFPA 2001. The releasing unit continuously supervises the detection, the actuation circuits, the manual release and abort stations, and the agent-container and pressure-supervisory devices; processes the detection logic; provides the pre-discharge delay and abort; and energizes the actuator that releases the agent. The releasing function is distinct from the building fire alarm system: the releasing unit transmits alarm, supervisory, and trouble signals to the building fire alarm system and the supervising station for occupant notification and off-premises reporting (see [[sync/fire-alarm-systems]]), but the agent release decision is made by the dedicated releasing unit.
+
+```datasheet
+label: Releasing Control Unit Listing
+type: radio
+options:
+ - "UL 864 listed for releasing service"
+default: "UL 864 listed for releasing service"
+```
+
+## Cross-Zoned Detection
+
+Automatic actuation shall require two independent detection inputs in alarm before the discharge sequence begins — a cross-zoned (or counting-zone) detection arrangement — so that a single detector in alarm cannot by itself release the agent. Cross-zoning prevents an extremely costly and disruptive accidental discharge from one faulty or transiently triggered detector while still providing fast response when a real fire is confirmed by detectors on two separate zones. Detectors shall be spot-type smoke detectors listed to UL 268, or aspirating (air-sampling) detection where early-warning sensitivity is required, located and spaced per NFPA 72 with the spacing reduced as required for the air movement in the protected space. Where the enclosure has a raised-floor void or a ceiling plenum that is part of the protected volume, detection shall be provided in those concealed spaces as well as at the ceiling.
+
+```datasheet
+label: Automatic Actuation Logic
+type: radio
+options:
+ - "Cross-zoned — two independent detection zones required to release (standard)"
+ - "Counting zone — two detectors on one engineered zone required to release"
+default: "Cross-zoned — two independent detection zones required to release (standard)"
+```
+
+```datasheet
+label: Detection Type
+type: select
+options:
+ - "Spot-type smoke detectors (UL 268), cross-zoned at ceiling"
+ - "Spot-type smoke detectors at ceiling, floor void, and ceiling plenum"
+ - "Air-sampling (aspirating) detection for early warning"
+ - "Air-sampling at room plus spot-type in voids"
+default: "Spot-type smoke detectors at ceiling, floor void, and ceiling plenum"
+```
+
+## Pre-Discharge Alarm, Time Delay, and Abort
+
+On confirmation of the cross-zoned alarm, the system shall sound a distinct pre-discharge alarm, activate warning signs and strobes at the entrances to and inside the protected space, initiate the ancillary shutdowns (HVAC and fan shutdown, damper and door closure), and begin a time delay before discharge. The time delay allows occupants to evacuate and allows an abort if the alarm is investigated and found not to warrant discharge; it shall be long enough for occupant egress yet short enough that fire growth does not exceed what the design concentration can extinguish, and shall not exceed the limit established by NFPA 2001 for the occupancy.
+
+A manual abort station, where provided, shall require constant manual pressure to hold the discharge in abort and shall not defeat the manual release; releasing the abort or operating the manual release shall allow or cause discharge. The abort shall not silence the pre-discharge alarm and shall be of the "dead-man" type so that the system cannot be left indefinitely disabled by a jammed or taped abort. A manual release station shall be provided at the means of egress from the protected space to allow a person to discharge the system immediately, overriding the time delay.
+
+```datasheet
+label: Pre-Discharge Time Delay
+type: range
+unit: s
+options:
+ min: 0
+ max: 60
+ setpoints: [0, 10, 30, 45, 60]
+default: 30
+```
+
+```datasheet
+label: Manual Stations Provided
+type: checkbox
+options:
+ - "Manual release (electric, at egress) — overrides time delay"
+ - "Manual abort (dead-man, constant pressure) — holds discharge during delay"
+ - "Maintenance lockout / disable switch with supervised trouble signal"
+default: "Manual release (electric, at egress) — overrides time delay"
+```
+
+## Ancillary Functions and Interlocks
+
+The releasing sequence shall shut down or reconfigure the equipment that would otherwise prevent the enclosure from holding the agent. Heating, ventilating, and air-conditioning units serving or communicating with the protected space shall be shut down, and dampers in the supply, return, and exhaust ducts crossing the enclosure boundary shall close, before or at the moment of discharge, so that the agent is not swept out of the enclosure. Self-closing doors and any doors held open by electromagnetic holders shall release and close. Where the protected hazard requires it and is permitted, electrical power to the protected equipment may be shut down on discharge; this interlock shall be applied only where intended, because cutting power to equipment can itself cause an unacceptable loss.
+
+```datasheet
+label: Ancillary Functions on Discharge
+type: checkbox
+options:
+ - "HVAC / air-handler shutdown serving the enclosure"
+ - "Supply / return / exhaust damper closure at enclosure boundary"
+ - "Door holder release / self-closing door closure"
+ - "Equipment power shutdown (only where intended)"
+ - "Signal to building fire alarm system and supervising station"
+default: "HVAC / air-handler shutdown serving the enclosure"
+```
+
+# Agent Storage and Distribution
+
+## Storage Containers
+
+Agent shall be stored in listed containers that are part of the listed system, located as close as practicable to the protected enclosure to keep pipe runs within the listed limits, and located where they are accessible for inspection, weighing or pressure checking, maintenance, and recharge. Halocarbon containers store the agent as a superpressurized liquid; inert-gas containers store the agent as a high-pressure gas, typically in a multi-cylinder bank with a manifold. Containers shall be secured against movement and the reaction forces of discharge, protected from physical damage and from temperatures outside their listed range, and provided with the pressure gauge or liquid-level indicating means required for routine inspection. Containers are pressure vessels and shall carry the markings and the hydrostatic-retest currency required by NFPA 2001 and DOT.
+
+```datasheet
+label: Container Arrangement
+type: radio
+options:
+ - "Single container (small halocarbon enclosure)"
+ - "Multiple containers, common manifold (large or multi-zone)"
+ - "Multi-cylinder high-pressure bank with manifold (inert gas)"
+default: "Single container (small halocarbon enclosure)"
+```
+
+```datasheet
+label: Container Contents Supervision
+type: checkbox
+options:
+ - "Low-pressure supervisory switch (signals loss of pressure)"
+ - "Liquid-level / weight monitoring (halocarbon)"
+ - "Manifold pressure gauge"
+default: "Low-pressure supervisory switch (signals loss of pressure)"
+```
+
+A loss of agent shall be detected: each container shall be monitored by a low-pressure supervisory switch (and, for halocarbon agents, by a means of detecting loss of agent quantity such as weight or liquid level) that transmits a supervisory signal to the releasing control unit. A container that has slowly lost agent or pressure without anyone knowing is one of the most dangerous latent failures of a clean-agent system, because the system appears intact but cannot reach the design concentration.
+
+## Discharge Piping and Fittings
+
+Discharge piping shall be the type and schedule required by the listed system and by NFPA 2001, sized and arranged exactly as the manufacturer's flow calculation requires; the pipe network is part of the listed system and shall not deviate from the calculated layout in length, size, fitting count, or tee orientation, because the flow calculation governs whether each nozzle delivers its share of agent within the discharge time. Piping shall be reamed and blown clear of cuttings and debris before assembly. Pipe and fittings shall be rated for the maximum pressure developed on discharge, which for inert-gas systems is high; the listed system establishes the required pressure rating. Piping shall be supported to resist the substantial reaction and thrust forces produced at tees, elbows, and nozzles during the rapid discharge.
+
+```datasheet
+label: Discharge Piping
+type: radio
+options:
+ - "Per listed-system flow calculation — size, schedule, layout, and fittings as calculated"
+default: "Per listed-system flow calculation — size, schedule, layout, and fittings as calculated"
+```
+
+```datasheet
+label: Piping Layout
+type: radio
+options:
+ - "Balanced (symmetrical) network"
+ - "Unbalanced network per listed flow calculation"
+default: "Balanced (symmetrical) network"
+```
+
+## Nozzles
+
+Discharge nozzles shall be the type, orifice, and quantity established by the flow calculation and shall be installed at the locations, heights, and orientations shown on the working drawings so that the agent disperses uniformly and reaches the design concentration throughout the protected volume within the discharge time. Nozzle coverage area and height limits are conditions of the listing and shall not be exceeded. Nozzles shall be oriented to avoid blowing directly on light, loose contents that the high-velocity discharge could disturb, and shall be kept clear of obstructions. Where the raised-floor void or ceiling plenum is part of the protected volume, nozzles shall be provided in those spaces.
+
+```datasheet
+label: Nozzle Coverage
+type: radio
+options:
+ - "Per listed nozzle coverage and height limits (type and orifice per flow calc)"
+default: "Per listed nozzle coverage and height limits (type and orifice per flow calc)"
+```
+
+```datasheet
+label: Protected Volumes Served by Nozzles
+type: checkbox
+options:
+ - "Room (above raised floor, below ceiling)"
+ - "Raised-floor void"
+ - "Ceiling plenum"
+default: "Room (above raised floor, below ceiling)"
+```
+
+## Discharge Time
+
+The discharge time is fixed by the agent family and is a pass/fail requirement of NFPA 2001. For halocarbon agents the system shall deliver at least 95 percent of the minimum design concentration within 10 seconds, because a halocarbon agent must reach concentration quickly to absorb heat before the fire grows and before agent decomposition products (such as hydrogen fluoride) accumulate. For inert-gas agents the discharge time is longer — typically not more than 60 seconds to reach the design concentration — because the agent extinguishes by oxygen displacement and a slower fill limits the over-pressure imposed on the enclosure as a large volume of gas is added. The flow calculation shall demonstrate compliance with the discharge time for the agent family.
+
+```datasheet
+label: Maximum Discharge Time — Halocarbon
+type: range
+unit: s
+options:
+ min: 6
+ max: 10
+ setpoints: [6, 8, 10]
+default: 10
+```
+
+```datasheet
+label: Maximum Discharge Time — Inert Gas
+type: range
+unit: s
+options:
+ min: 30
+ max: 120
+ setpoints: [30, 60, 90, 120]
+default: 60
+```
+
+# Enclosure Integrity
+
+## Hold (Soak) Time and Leakage
+
+The enclosure shall retain the agent at or above the concentration needed to prevent re-ignition for a minimum hold (soak) time after discharge, in accordance with NFPA 2001. Establishing the concentration is not enough; the fire is extinguished and hot surfaces cool over the hold period, and if the agent leaks away too quickly through unsealed penetrations, door undercuts, dampers that did not close, or a porous boundary, the fire can re-ignite. The required hold time is commonly 10 minutes unless a different value is justified by the time the hazard will go unattended after discharge. The enclosure boundary shall be made substantially tight: cable and conduit penetrations sealed, dampers arranged to close on discharge, doors self-closing and reasonably gasketed, and the floor void and ceiling plenum boundaries sealed where they form part of the enclosure.
+
+```datasheet
+label: Minimum Agent Hold (Soak) Time
+type: range
+unit: min
+drawing_ref: true
+options:
+ min: 5
+ max: 30
+ setpoints: [5, 10, 15, 20, 30]
+default: 10
+```
+
+## Door-Fan (Enclosure-Integrity) Test
+
+The enclosure integrity shall be verified by a door-fan (enclosure-integrity) test performed in accordance with the procedure in NFPA 2001, both as a design tool and at acceptance. A calibrated fan mounted in a doorway pressurizes and depressurizes the enclosure while measuring the airflow required to hold a series of pressures; from the measured leakage and the enclosure geometry the test calculates the predicted agent retention (hold) time at the design concentration descending to the protected height. This test substitutes for an actual agent discharge — it is impractical and wasteful to verify hold time by discharging agent — and it locates leakage paths so they can be sealed. The system shall not be accepted until the door-fan test demonstrates that the enclosure will hold the agent for at least the required hold time. Where the test fails, the leakage paths shall be sealed and the test repeated until it passes.
+
+```datasheet
+label: Enclosure-Integrity Verification
+type: radio
+options:
+ - "Door-fan test per NFPA 2001 — predicted hold time meets or exceeds required hold time"
+default: "Door-fan test per NFPA 2001 — predicted hold time meets or exceeds required hold time"
+```
+
+# Pressure Relief Venting
+
+The protected enclosure shall be provided with pressure relief sized for the agent and the discharge so that the enclosure structure is not damaged by the pressure transient of discharge, in accordance with NFPA 2001. The discharge of agent changes the enclosure pressure: a halocarbon discharge can cause both a brief negative excursion (as cold liquid vaporizes) and a positive excursion, while an inert-gas discharge adds a large volume of gas that produces a sustained positive over-pressure. A modern, tightly sealed enclosure — exactly the kind that holds the agent well — cannot relieve this pressure through incidental leakage and can have its walls, ceiling, or floor structurally over-stressed unless a pressure-relief vent is provided. The relief vent shall be sized from the agent quantity and discharge rate and the enclosure's allowable pressure, and shall be a listed barometric or motorized damper-type relief that opens during discharge and otherwise stays closed so it does not itself become a leakage path that shortens the hold time.
+
+```datasheet
+label: Pressure Relief Provided
+type: radio
+options:
+ - "Pressure relief vent sized per NFPA 2001 for agent quantity and enclosure strength"
+ - "Engineering analysis confirms enclosure leakage adequate — no added vent (rare; documented)"
+default: "Pressure relief vent sized per NFPA 2001 for agent quantity and enclosure strength"
+```
+
+```datasheet
+label: Pressure Relief Vent Type
+type: select
+options:
+ - "Barometric (self-closing) relief damper"
+ - "Motorized relief damper interlocked to discharge"
+ - "Per drawings"
+default: "Barometric (self-closing) relief damper"
+```
+
+```datasheet
+label: Enclosure Allowable Pressure
+type: range
+unit: "lb/ft²"
+drawing_ref: true
+options:
+ min: 5
+ max: 50
+ setpoints: [5, 10, 15, 25, 50]
+default: 10
+```
+
+# Testing and Commissioning
+
+## Acceptance Test
+
+The complete system shall be tested and commissioned at acceptance in accordance with NFPA 2001 and NFPA 72, with the AHJ witnessing where required. The acceptance test shall verify the detection and its cross-zoning logic; the pre-discharge alarm and warning signs; the time delay and its duration; the manual release and the abort behavior; the supervision of the detection, actuation, and container-pressure circuits; the transmission of alarm, supervisory, and trouble signals to the building fire alarm system; and every ancillary function (HVAC and fan shutdown, damper and door closure, and any power shutdown). The actuation circuit shall be verified without discharging agent by substituting a means that confirms the actuator would fire, in accordance with the manufacturer's instructions; agent shall not be discharged for acceptance unless specifically required and accepted.
+
+```datasheet
+label: Acceptance Test Scope
+type: checkbox
+options:
+ - "Cross-zoned detection logic verified"
+ - "Pre-discharge alarm, signs, and strobes verified"
+ - "Time delay duration verified"
+ - "Manual release and abort behavior verified"
+ - "Circuit supervision (detection, actuation, container pressure) verified"
+ - "Ancillary functions (HVAC, dampers, doors, power) verified"
+ - "Signal to fire alarm system / supervising station verified"
+ - "Actuation verified without agent discharge"
+default: "Cross-zoned detection logic verified"
+```
+
+## Enclosure-Integrity Test at Acceptance
+
+The door-fan test shall be performed at acceptance after all penetrations are sealed and the enclosure is in its final, in-service condition, and the predicted hold time shall meet or exceed the required hold time before the system is accepted. The test result shall be recorded in the closeout documents and shall establish the baseline against which future periodic enclosure-integrity tests are compared, since enclosure tightness degrades over time as cables are added and penetrations are opened.
+
+# Installation
+
+## General
+
+The Contractor shall install the system in accordance with this standard, the approved working drawings, NFPA 2001, NFPA 72, NFPA 70, and the listed-system manufacturer's design and installation manual. Where these conflict, the more stringent governs, and no installation shall deviate from the conditions of the listing. Piping shall be installed to the calculated layout, reamed and cleaned, pressure-tight, and supported to resist discharge reaction forces. Nozzles shall be installed at the locations and orientations shown. Detection, manual stations, alarms, and signs shall be installed at the heights and locations required for visibility and reach.
+
+## Signage
+
+Warning and instruction signs shall be provided in accordance with NFPA 2001 at the entrances to and inside the protected space and at the agent storage and control locations: a sign warning that the space is protected by a clean-agent system and that occupants shall evacuate on the pre-discharge alarm; a sign at the manual release identifying its function; a sign at the abort identifying its function and limits; and a sign at any lockout/disable switch. Signs shall be permanent and legible.
+
+```datasheet
+label: Warning and Instruction Signs
+type: checkbox
+options:
+ - "Entrance: clean-agent protection / evacuate on alarm"
+ - "Manual release station identification"
+ - "Abort station identification and limits"
+ - "Lockout / disable (out-of-service) sign"
+ - "Agent storage room identification"
+default: "Entrance: clean-agent protection / evacuate on alarm"
+```
+
+# Delivery, Storage, and Handling
+
+Agent containers shall be delivered fully charged, with the agent type and quantity and the charge pressure or fill weight marked on each container, and with the actuation devices secured for transport. Containers shall be kept capped, secured upright or as the manufacturer requires, and protected from physical damage and from temperatures outside their listed range until installed. Containers are pressure vessels transported under DOT rules; the Contractor shall verify the hydrostatic-retest currency of each container on receipt and shall not install a container whose retest is out of date. Actuation devices (electric, pneumatic, or cartridge actuators) shall be kept disconnected or secured so that the system cannot discharge during handling and installation, and shall be connected and armed only as the final commissioning step after the detection and control system have been verified.
+
+```datasheet
+label: Container Delivery Condition
+type: radio
+options:
+ - "Factory-charged, marked with agent type/quantity and fill weight or pressure, retest current"
+default: "Factory-charged, marked with agent type/quantity and fill weight or pressure, retest current"
+```
+
+# Warranty
+
+The Contractor shall warrant the clean-agent system installation against defects in materials and workmanship for a period of not less than one year from substantial completion, or for the period stated in the contract documents if longer. Any defect in the detection, releasing, actuation, piping, or nozzles, and any failure of the enclosure-integrity provisions installed under this scope that causes the system to fail to reach or hold the design concentration, shall be corrected at the Contractor's expense, including the cost of recharging agent expended in correcting the defect. Correction of a deficiency that requires re-sealing the enclosure and re-running the door-fan test shall be performed and re-verified at the Contractor's expense.
+
+# Spare Parts
+
+The Contractor shall provide the spare components recommended by the listed-system manufacturer for maintaining the system in service without delay, in accordance with NFPA 2001 and the contract documents. As a minimum, the Contractor shall provide spare detectors of each type installed and the means (a spare or rechargeable container arrangement) by which the system can be returned to service after a discharge with minimum downtime, since a discharged system leaves the protected space unprotected until the agent is recharged. The Owner shall be advised of the agent recharge source and the container hydrostatic-retest schedule so the system is maintained ready throughout its life.
+
+```datasheet
+label: Spare Parts and Recharge Provisions
+type: checkbox
+options:
+ - "Spare detector(s) of each installed type"
+ - "Spare actuation device(s)"
+ - "Agent recharge source identified for prompt return to service"
+ - "Container hydrostatic-retest schedule provided to Owner"
+default: "Agent recharge source identified for prompt return to service"
+```