1 Scope
NOTE This standard covers the assembled accessories and inline specialties of the domestic water distribution system: PRV stations, domestic hot water expansion tanks, dielectric isolation fittings, inline strainers, pipe identification and valve tagging, pipe sleeves and escutcheons, firestopping at penetrations, and equipment isolation/drain valve packages. (1.1)
NOTE These are the components that connect, protect, identify, and isolate the piping system but are neither pure piping nor the fixture-protection specialties owned by adjacent standards. (1.2)
NOTE This standard's defensible territory is the assembled system accessory. (1.3)
NOTE The corpus has three close neighbors, and the boundary against each is deliberate. Piping, fittings, joining, hangers, and insulation belong to
Domestic Water Piping. General-duty isolation, check, and balancing valves belong to
Plumbing Piping Valves. Fixture-protection specialties -- water hammer arresters, thermostatic mixing valves, hose bibbs, trap primers -- belong to
Plumbing Specialties. What remains, and what this standard owns, is the assembled accessory: the PRV station as a station, the expansion tank, the dielectric break, the strainer, the identification system, the penetration treatment, and the equipment isolation kit.
(1.4) NOTE The work of this standard applies to domestic cold water, domestic hot water, and hot water recirculation piping inside the building envelope. (1.5)
NOTE It applies downstream of the building water service entrance and upstream of the fixture supply stops. The site service main from the utility to the meter vault is outside this scope. (1.6)
NOTE The following are specifically excluded and are specified elsewhere. (1.7)
- General-duty isolation, check, and balancing valves -- Plumbing Piping Valves
- Water hammer arresters, thermostatic mixing valves (master and point-of-use), hose bibbs, freezeless wall hydrants, and trap primers -- Plumbing Specialties
- Supply and distribution piping materials, fittings, joining methods, hangers, and insulation -- Domestic Water Piping
- Backflow prevention assemblies (RPZ, double-check, PVB) at the building or zone level -- Backflow Prevention
- Water heaters, tankless heaters, and storage equipment -- Water Heaters
- Sanitary drainage specialties, cleanouts, and backwater valves -- Sanitary Drainage Specialties
- Hydronic, chilled, and condenser water piping accessories -- Chilled And Condenser Water Piping
- Fire protection piping, specialties, and control valves -- Fire Protection Piping
- The site water service main upstream of the building water service entrance
NOTE A PRV is not a backflow preventer. (1.8)
NOTE A pressure-reducing valve regulates downstream pressure; it provides no backflow protection. Where the code or the authority having jurisdiction requires backflow prevention, a separate assembly per
Backflow Prevention is provided in addition to any PRV. Treating the two as interchangeable is a recurring design error.
(1.9) 2 Referenced Standards
2.1Equipment, materials, and installation shall comply with the latest adopted edition of each of the following unless a specific edition is cited.
2.2Where referenced standards conflict, the more stringent requirement shall govern unless the Engineer of Record directs otherwise in writing.
NOTE Where this standard and the locally adopted plumbing code conflict, the plumbing code shall govern. (2.3)
| Standard |
Title |
| ASSE 1003 / CSA B356 |
Performance Requirements for Water Pressure Reducing Valves for Domestic Water Distribution Systems |
| ASSE 1011 |
Performance Requirements for Hose Connection Vacuum Breakers |
| NSF/ANSI 61 |
Drinking Water System Components -- Health Effects |
| NSF/ANSI/CAN 372 |
Drinking Water System Components -- Lead Content (Lead-Free) |
| ASME A112.1.2 |
Air Gaps in Plumbing Systems |
| ASME B16.18 |
Cast Copper Alloy Solder Joint Pressure Fittings |
| ASME B31.9 |
Building Services Piping |
| ASME A13.1 |
Scheme for the Identification of Piping Systems |
| ASTM F1508 |
Angle-Style, Thermoplastic Expansion Tank Connectors |
| PDI WH-201 |
Water Hammer Arresters -- Certification and Sizing |
| IPC |
International Plumbing Code, Chapter 6 (Water Supply and Distribution) |
| UPC |
Uniform Plumbing Code, Chapter 6 (Water Supply and Distribution) |
| AWWA M22 |
Sizing Water Service Lines and Meters |
| ASHRAE 90.1 |
Energy Standard for Buildings Except Low-Rise Residential |
3 Submittals
3.1 Action Submittals
3.1.1The Contractor shall submit the following action submittals for review before fabrication, ordering, or installation:
- Product data for each PRV, expansion tank, strainer, dielectric fitting, escutcheon, identification marker, and equipment isolation kit, including capacity, pressure rating, and material certifications
- NSF/ANSI 61 and NSF/ANSI/CAN 372 certification for every component in contact with potable water
- PRV station shop drawings showing valve, strainer, isolation valves, gauge, and bypass configuration with dimensioned clearances
- Expansion tank acceptance-volume calculation worksheet showing system water volume, cold-fill pressure, relief valve set pressure, and temperature rise inputs
- Pipe identification schedule listing legend text, color scheme, marker type, and spacing for each service
- Valve schedule correlating each valve tag number to service, location, and normal operating position
☑ Product data for specialties and valve packages
☑ NSF/ANSI 61 and 372 potable-water certifications
☑ PRV station shop drawings
☑ Expansion tank acceptance-volume calculation
☐ Pipe identification schedule
☐ Valve schedule
3.2.1The Contractor shall submit the following informational submittals:
- Manufacturer installation instructions for PRVs, expansion tanks, and dielectric fittings
- UL-listed firestop system data sheets for each penetration condition
- Field test reports for PRV setpoint verification and expansion tank pre-charge adjustment
☑ Manufacturer installation instructions
☑ UL firestop system data sheets
☑ PRV setpoint and pre-charge field test reports
3.3 Closeout Submittals
3.3.1The Contractor shall submit the following closeout submittals before substantial completion:
- Operation and maintenance data for PRVs, expansion tanks, and strainers, including parts lists and recommended service intervals
- As-recorded PRV setpoints, expansion tank pre-charge pressures, and the completed valve schedule
- Warranty documentation for each specialty
☑ O&M data for specialties
☑ As-recorded setpoints, pre-charge, and valve schedule
☑ Warranty documentation
4 Quality Assurance
4.1Every component in contact with potable water shall carry third-party certification to NSF/ANSI 61.
4.2Every wetted component shall comply with the lead-free requirement of NSF/ANSI/CAN 372, with a weighted average lead content of the wetted surfaces not exceeding 0.25%.
4.3Each PRV shall be certified to ASSE 1003 / CSA B356.
4.4Each hose-end drain valve serving as an equipment service connection shall be fitted with a hose connection vacuum breaker certified to ASSE 1011.
NOTE The lead-free certification mark is the Safe Drinking Water Act compliance basis and is not optional for any potable-water component. (4.5)
4.6Specialties of one type shall be the product of a single manufacturer to maintain consistent parts and service interfaces.
4.7Pressure design of all piping assemblies covered by this standard shall conform to ASME B31.9, Building Services Piping.
5 Environmental and Service Conditions
NOTE Components shall be selected for the service in which they are installed: domestic cold water, domestic hot water, or hot water recirculation. (5.1)
NOTE Hot water recirculation is the most demanding service because it combines continuous flow, elevated temperature, and continuous thermal cycling. Components rated only for cold water -- particularly elastomeric flexible connectors and dielectric inserts -- fail prematurely in recirculation service. (5.2)
5.3Components in hot water and recirculation service shall be rated for continuous operation at not less than 180 °F.
5.4Materials in contact with potable water shall not impart taste, odor, color, or contaminants in excess of NSF/ANSI 61 limits.
NOTE Insulation on hot water piping serving equipment isolation assemblies shall conform to the applicable ASHRAE 90.1 pipe insulation tables. (5.5)
NOTE Insulation thickness governs the outside diameter that escutcheons and sleeves must accommodate; coordinate the insulated OD before ordering trim. (5.6)
6 Pressure-Reducing Valve Stations
NOTE IPC Section 604.8 and UPC Section 608 trigger when the static service pressure entering the building exceeds 80 psi. The station is more than the valve: it is the valve plus its strainer, isolation valves, downstream gauge, and -- on most commercial systems -- a bypass. (6.1)
6.2A pressure-reducing valve shall be installed on the building water service where the static incoming pressure exceeds 80 psi.
NOTE The PRV setpoint shall be the required pressure at the valve outlet, not the desired pressure at the highest or furthest fixture. (6.3)
NOTE The single most common PRV error is setting the outlet pressure to the target fixture pressure without accounting for the static head and friction loss between the valve and the upper floors. The Engineer of Record verifies that the reduced downstream design pressure remains adequate for the highest and most remote fixtures at peak demand. (6.4)
6.5The Engineer of Record shall verify that the reduced downstream design pressure is adequate for the highest and most remote fixtures at peak demand before the setpoint is fixed.
6.5.1 PRV Configuration
NOTE The station configuration shall be selected for the criticality of the served load. (6.5.1.1)
NOTE A single PRV with no bypass takes the entire system offline if the valve fails during peak demand. For critical loads -- hospitals, laboratories, manufacturing, and any occupancy that cannot tolerate an interruption -- the choice is between a parallel redundant station and a full-flow bypass that allows the valve to be serviced without dropping the system. (6.5.1.2)
6.5.1.3A full-flow bypass or a parallel redundant PRV shall be provided on systems serving critical or continuous-process loads.
● Single-stage PRV with integral strainer and downstream gauge
○ Single PRV with full-flow bypass assembly
○ Dual-PRV parallel redundant station
6.5.1.4PRV downstream setpoint pressure
6.5.1.5The PRV outlet pressure shall remain within ±10% of the setpoint from zero flow to full rated flow, per ASSE 1003.
6.5.1.6The PRV shall be rated for an inlet maximum allowable working pressure of not less than 250 psi.
6.5.2 PRV Body and Trim
6.5.2.1PRV body material
○ Bronze body with bronze trim
● Bronze body with stainless steel trim
○ Cast iron body with bronze trim (NPS 2 and larger)
6.5.2.2The PRV shall include an integral or upstream strainer to protect the seat from debris.
6.5.2.3A pressure gauge shall be installed downstream of each PRV.
6.5.2.4Downstream pressure gauge range and type
0-160 psi, 2-1/2 in. dial, glycerin-filled
0-200 psi, 2-1/2 in. dial, glycerin-filled
0-160 psi, 4-1/2 in. dial, glycerin-filled
NOTE The downstream gauge shall be glycerin-filled to resist vibration and pulsation damage. (6.5.2.5)
6.5.2.6Isolation valves shall be provided upstream and downstream of each PRV to permit removal without draining the system.
7 Inline Strainers
NOTE Inline strainers protect downstream specialties and equipment from debris carried in the supply. (7.1)
NOTE A strainer is only useful if it can be cleaned in place. A strainer in a confined space without a blow-down valve turns routine screen cleaning into a near-disassembly maintenance call. (7.2)
7.3Each inline strainer shall be provided with a blow-down valve at the screen pocket.
7.4Each inline strainer shall be installed with clearance sufficient to remove and clean the screen in place.
7.5Strainer type
● Y-type, bronze body, 304 stainless screen
○ Basket type, single
○ Duplex basket type (continuous-flow mains, NPS 3 and larger)
7.6Strainer screen mesh
40-mesh (0.017 in. openings)
100-mesh (upstream of PRV where required)
20-mesh (coarse, large mains)
7.7Where a strainer serves a continuous-flow main that cannot be interrupted for cleaning, a duplex basket strainer shall be provided.
8 Domestic Hot Water Expansion Tanks
NOTE IPC Section 607 and UPC Section 608 require thermal expansion control on closed systems -- defined as any system with a check valve, backflow preventer, or PRV between the heater and the street, because that device closes the system and removes the street main as an expansion sink. Water expands roughly 2% to 3% when heated from cold fill to storage temperature, and with nowhere to go that expansion drives the system pressure up against the relief valve. (8.1)
8.2A thermal expansion tank shall be installed on the cold water supply to each closed domestic hot water system.
NOTE The expansion tank acceptance volume shall be calculated, not estimated. (8.3)
NOTE Sizing an expansion tank from a rule of thumb or from memory is a recurring and consequential error. An undersized tank cannot absorb the thermal expansion, so system pressure cycles up to the relief valve setting; the symptoms are PRV chattering, dripping relief valves, and premature relief valve wear. The acceptance volume is calculated from system water volume, cold-fill pressure, relief valve set pressure, and temperature rise; the manufacturer's published worksheet or the equivalent ASME method is required. (8.4)
8.5The expansion tank acceptance volume shall be calculated from the system water volume, cold-fill pressure, relief valve set pressure, and temperature rise, using the manufacturer's published worksheet or the equivalent ASME method.
NOTE The expansion tank pre-charge pressure shall equal the static cold-fill pressure at the tank location and shall be field-verified and adjusted before the system is placed in service. (8.6)
NOTE Factory pre-charge defaults to a nominal value -- commonly 40 psi -- that is correct for almost no multi-story building. A tank in an upper-floor mechanical room sees lower static fill pressure than one in the basement, so the pre-charge must be set to the actual cold-fill pressure at the tank elevation. A tank installed at the factory default in a building whose fill pressure differs will not perform as sized. (8.7)
8.8The expansion tank pre-charge pressure shall be field-verified and adjusted to match the system cold-fill pressure at the tank location before the system is filled.
8.9Expansion tank type
● Bladder type (polypropylene-lined bladder, ASME-rated)
○ Diaphragm type (EPDM diaphragm)
8.10Expansion tank acceptance volume
8.11Expansion tank field-set pre-charge pressure
Per drawings — cold-fill pressure at tank elevation from hydraulic schedule (deferred by default)
8.12Relief valve set pressure used in the sizing calculation
8.13The expansion tank shell shall be ASME-rated for the system working pressure, and the bladder or diaphragm shall be NSF/ANSI 61 certified for potable water.
9 Dielectric Isolation Fittings
NOTE A dielectric break is required at every connection between dissimilar metals. (9.1)
NOTE Where copper joins ferrous, galvanized, or black steel piping, the two metals form a galvanic couple, and in high-conductivity water the copper can perforate within two to five years. A dielectric union, flange, or nipple interrupts the electrical path and stops the galvanic cell. The break is provided at every such transition, not only at the most visible ones. (9.2)
9.3A dielectric union, flange, or nipple shall be installed at every connection between copper and ferrous, galvanized, or black steel piping.
NOTE Dielectric inserts on hot water service shall be nylon rated for not less than 250 °F; PVC inserts shall not be used on hot water lines. (9.4)
NOTE PVC inserts soften and fail above 140 °F. Because hot water and recirculation lines operate above that threshold, a PVC-insert dielectric union is a failure waiting to happen. (9.5)
9.6Dielectric inserts in hot water and recirculation service shall be nylon rated for not less than 250 °F.
9.7PVC-insert dielectric fittings shall not be used in hot water or recirculation service.
9.8Dielectric fitting type
● Threaded dielectric union, NPS 1/4 to NPS 2
○ Dielectric flange kit (gasket, sleeves, washers), NPS 2 and larger
○ Dielectric nipple
9.9Dielectric union rating
250 psi CWP, 250 °F (nylon insert)
300 psi CWP, 300 °F (nylon insert)
10 Equipment Isolation and Drain Valve Packages
NOTE Equipment served by the domestic water system shall be isolatable and drainable without affecting the rest of the distribution. (10.1)
NOTE Water heaters, booster pumps, and water treatment equipment must be serviceable in place. The isolation package -- full-port ball valves on each connection, a hose-end drain valve, unions for removal, and gauge and thermometer provisions -- lets a technician valve off, drain, and remove the equipment without shutting down the building. The package may be a factory kit or field-assembled from the same components. (10.2)
10.3Each water heater, booster pump, and water treatment unit shall be provided with full-port isolation valves on each piping connection.
10.4A hose-end drain valve with cap and chain shall be provided at the low point of each isolated equipment connection.
10.5Each hose-end drain valve used as a service connection shall be fitted with a hose connection vacuum breaker certified to ASSE 1011.
10.6Union connections shall be provided within 12 in. of each side of the equipment to permit removal.
10.7Isolation valves in the equipment package shall be full-port ball valves rated not less than 600 WOG or 250 psi CWP.
10.8A pressure gauge port and a thermometer well shall be provided on the equipment package where the equipment requires monitoring.
10.9Equipment isolation valve package
● Pre-fabricated isolation kit (full-port valves, hose-end drain, unions, gauge ports)
○ Field-assembled package from individual components
NOTE Flexible connectors at rotating equipment shall be rated for the system pressure and temperature. (10.10)
NOTE A rubber flexible connector rated for 125 psi cold water will fail in hot water recirculation service. Galvanized braid corrodes rapidly in hot water; the connector's temperature rating must cover the actual service conditions, not just a nominal cold water rating. (10.11)
10.12Flexible connectors at pumps shall be stainless-braided and rated for not less than 150 psi and 180 °F in hot water service.
10.13Flexible connector type
● Braided stainless steel hose connector
○ Rubber-isolated swivel pump connector
10.14Flexible connector pressure rating
150 psi, 180 °F (hot water and recirculation)
125 psi, 140 °F (cold water only)
11 Meter Bypass Assemblies
NOTE A service-weight meter bypass assembly permits meter service without interrupting building supply. (11.1)
NOTE Where the building cannot tolerate a supply interruption during meter maintenance or replacement, a bypass around the meter is provided with isolation valves on the meter legs and the bypass leg. Sizing follows the guidance of AWWA M22 for the service and meter combination. (11.2)
11.3Meter bypass assemblies, where provided, shall be configured and sized in accordance with AWWA M22.
11.4Meter bypass isolation valves shall be full-port to avoid adding pressure loss to the service entrance.
11.5Meter bypass assembly
○ Service-weight bypass with full-port isolation valves
● No bypass (single meter run)
NOTE All domestic water piping shall be identified by service, with flow direction, per ASME A13.1. (12.1)
NOTE Identification is a legend plus a directional arrow plus a code-compliant background color. A marker that reads only "HW" without a flow arrow does not satisfy ASME A13.1 and generates field RFIs and non-conformance reports. The legend must name the service and the arrow must show flow direction. (12.2)
12.3Each pipe identification marker shall include the service legend and a flow-direction arrow.
12.4Pipe identification markers shall use the ASME A13.1 color scheme for the service background and legend.
NOTE Pipe identification markers shall be applied at the spacing required by ASME A13.1. (12.5)
NOTE ASME A13.1 calls for a marker at least every 25 ft on straight runs of 50 ft or more, at least every 10 ft on runs shorter than 50 ft, and at each side of every wall, floor, and ceiling penetration, at each valve, and at each branch. (12.6)
12.7Pipe identification markers shall be applied at least every 25 ft on straight runs, at each side of every wall, floor, and ceiling penetration, at each valve, and at each branch.
12.8Marker type
● Adhesive wrap-around marker with flow arrow
○ Snap-on marker with flow arrow
○ Stenciled legend with applied arrow
12.9Each valve other than a fixture supply stop shall be identified with an engraved tag keyed to the valve schedule.
12.10Valve tag material
Engraved brass, 1-1/2 in. round
Engraved anodized aluminum, 1-1/2 in. round
Engraved laminated phenolic
12.11A laminated valve-schedule nameplate shall be mounted in each mechanical room correlating tag numbers to service, location, and normal position.
13 Pipe Sleeves, Escutcheons, and Firestopping
NOTE Every pipe passing through a wall, floor, or ceiling shall be sleeved. (13.1)
NOTE A sleeve protects the pipe at the penetration, accommodates movement, and -- at rated assemblies -- carries the firestop system. The sleeve and its annular fill are selected for whether the assembly is fire-rated. (13.2)
13.3Each pipe penetration of a wall, floor, or ceiling shall be provided with a sleeve.
13.4Sleeve material and annular fill
● Galvanized steel sleeve with UL-listed intumescent firestop sealant (rated assemblies)
○ PVC sleeve, sealant fill (non-rated assemblies)
13.5At fire-rated assemblies, the penetration shall be firestopped with a UL-listed firestop system appropriate to the pipe, sleeve, and rating.
13.6The annular space shall provide a minimum clearance of 1/2 in. on each side of the pipe, including its insulation, and shall not exceed the maximum gap of the listed firestop system.
NOTE An escutcheon shall be provided at each exposed pipe penetration in finished areas. (13.7)
NOTE Escutcheons must be sized for the insulated outside diameter of the pipe, not the bare pipe. Where the pipe is insulated under a separate section, the insulated OD is a coordination item and a common RFI source; confirm the insulated OD before ordering. (13.8)
13.9Each exposed pipe penetration in a finished area shall be fitted with an escutcheon sized for the insulated outside diameter of the pipe.
13.10Escutcheon type and finish
● Split-ring, chrome-plated brass
○ One-piece, chrome-plated brass
○ Split-ring, stainless steel
○ Split-ring, painted to match finish
14 Testing
NOTE The completed system shall be hydrostatically tested before it is concealed or placed in service. (14.1)
NOTE The hydrostatic test verifies that every joint and specialty connection in the assembled system holds pressure. PRVs and expansion tanks are isolated or removed during the test because their working pressure and acceptance volume would otherwise mask or be damaged by the test pressure. (14.2)
14.3The piping system, including specialty connections, shall be hydrostatically tested at 1.5 times the working pressure or 100 psi above the working pressure, whichever is greater, for not less than 4 hours with no visible leakage, per IPC Section 312.5.
14.4PRVs and expansion tanks shall be isolated or removed during the hydrostatic test to protect them from the test pressure.
14.5After the system is filled and pressurized, the PRV setpoint shall be verified and adjusted to the specified downstream pressure.
14.6After the system is filled, the expansion tank pre-charge shall be verified against the static cold-fill pressure at the tank and adjusted as required.
14.7Each inline strainer shall be blown down and the screen inspected after the system has been flushed.
14.8Hydrostatic test pressure basis
● 1.5 x working pressure or working + 100 psi, whichever is greater
○ Fixed value as directed by the authority having jurisdiction
14.9Hydrostatic test duration
15 Installation
15.1Specialties shall be installed in the orientation and flow direction shown by the manufacturer and shall be accessible for service.
15.2Each PRV station shall be installed with clearance to read the gauge, adjust the setpoint, and remove the valve without disturbing adjacent work.
NOTE Each expansion tank shall be supported independently of the connected piping and located where its pre-charge can be checked and adjusted in service. (15.3)
NOTE A tank that hangs on the piping it serves overloads the connection and makes the air valve inaccessible; mount it on a dedicated support with the air valve reachable. (15.4)
15.5Each expansion tank shall be mounted on a dedicated support with its air valve accessible.
15.6Dielectric fittings shall be installed at the metal transition with the insulating insert oriented per the manufacturer's installation instructions.
15.7Dielectric fittings shall not be bridged by a metallic bonding jumper that would defeat the galvanic isolation.
15.8Inline strainers shall be installed with the screen pocket oriented to drain and with the blow-down valve accessible.
15.9Pipe identification, valve tags, and the valve-schedule nameplate shall be installed after the system is flushed, tested, and accepted.
16 Delivery, Storage, and Handling
16.1Specialties shall be delivered in the manufacturer's original packaging with certification labels intact.
16.2Components in contact with potable water shall be kept capped or bagged until installed to keep the wetted surfaces clean.
16.3Expansion tanks shall be stored upright and protected from impact that could damage the bladder or diaphragm.
16.4Gauges and flexible connectors shall be protected from impact and from exposure that could degrade elastomers before installation.
17 Warranty
17.1Each specialty shall be warranted against defects in materials and workmanship for the manufacturer's standard period.
17.2Warranty period
1 year from substantial completion
2 years from substantial completion
Manufacturer standard period
17.3The warranty shall cover replacement of defective PRV cartridges, expansion tank bladders, and strainer screens within the warranty period.
18 Spare Parts
18.1The Contractor shall furnish spare parts to support first-year maintenance.
18.1.1The Contractor shall furnish the following spare parts:
- One spare strainer screen for each strainer size installed
- One spare PRV repair cartridge for each PRV size installed
- One set of replacement gaskets for each dielectric flange size installed
☑ One spare strainer screen per size
☑ One spare PRV repair cartridge per size
☐ One set of dielectric flange gaskets per size