Correct
alarm check valve installation is not just about connecting the pipe — it determines whether the system will activate reliably in a fire, whether it will generate false alarms from pressure surges, and whether it will pass the Authority Having Jurisdiction (AHJ) inspection before the building opens. This guide covers every installation requirement specified by
NFPA 13 and GB 50084, from valve room design through trim piping to final commissioning.
Before Installation — 5 Things to Confirm
Before placing the valve in the riser, confirm the following. Errors at this stage are expensive to correct after the pipework is complete:
1
Correct valve type for the systemA
wet alarm valve (ZSFZ) is only for wet-pipe systems in spaces maintained ≥ 4°C. A
dry alarm valve (ZSFC) is required for any zone where distribution pipework will be below 4°C. Installing a wet alarm valve in a freeze-risk zone is a code violation and will result in system failure.
2
Correct DN size matches the riserThe alarm check valve DN must match the riser pipe diameter. Do not reduce or increase the valve DN relative to the riser — this creates a hydraulic restriction or expansion that affects pressure calculations and may void the GB 5135.6 / NFPA 13 hydraulic design compliance.
3
Correct flange drilling standardCA-FIRE ZSFZ is available in GB, ANSI B16.5, and DIN PN16 flange drilling. Confirm the flange standard matches the adjacent pipework before delivery. Mismatched bolt hole patterns cannot be corrected on site without machining.
4
Valve room meets code requirementsGB 50084 and NFPA 13 both specify minimum requirements for the alarm valve room — dimensions, drainage, lighting, heating (≥ 4°C), and access. Confirm the valve room design is approved before installation begins. The valve room is inspected by the AHJ as part of system acceptance.
5
Flow direction arrow on valve bodyEvery CA-FIRE alarm check valve body has a flow direction arrow cast or stamped on the body. Water must flow in the direction of the arrow — from supply main (below) to distribution pipework (above). Installing the valve backwards will prevent the clapper from opening on activation.
Valve Orientation — Why Upright Installation Is Mandatory
The alarm check valve must be installed in the upright (vertical) position with water flowing upward through the valve body. This is one of the most frequently misunderstood installation requirements, and violating it is one of the most common causes of alarm valve failure in the field.
✓ Correct: Upright (Vertical)
Valve body vertical. Supply enters from the bottom. Distribution pipework exits from the top. Clapper is gravity-seated — its own weight helps maintain the seal in standby. Flow direction arrow points upward.
The clapper disc hangs on its hinge in the “closed” position under gravity. Supply pressure and gravity together keep it sealed. On activation, supply pressure lifts the clapper upward — smooth, reliable operation every time.
✗ Incorrect: Horizontal Installation
The ZSFZ, ZSFC, and all CA-FIRE swing-clapper alarm valves are
not suitable for horizontal installation.
In a horizontal position, the clapper disc hangs at 90° to its design orientation. Gravity no longer assists seating — the clapper may rest partially open or reseat unreliably after a test or activation. This causes water to leak into the alarm port, triggering continuous false alarms and preventing the system from returning to standby after reset.
⚠️ Alarm Check Valve Horizontal Installation — Not Permitted
NFPA 13 and GB 50084 both require alarm check valves to be installed in the upright vertical position. If the riser layout makes vertical installation difficult, the solution is to redesign the riser configuration using pipe offsets — not to install the alarm valve horizontally. Contact
sales@ca-fire.com if you have a non-standard riser configuration that requires design advice.
Alarm Check Valve Installation Height Requirements
GB 50084 and NFPA 13 specify minimum and maximum installation heights for alarm check valves — measured from the finished floor level to the centre of the valve body inlet.
Alarm Check Valve Installation Height — Code Requirements
Minimum Height
0.8 m
Above finished floor level. Ensures adequate clearance for main drain valve operation and visual inspection of the valve body and lower trim components.
Maximum Height
1.2 m
Above finished floor level (GB 50084). Ensures the pressure gauges, drain valve, and control handles can be operated by standing personnel without a ladder or platform.
Practical Target
1.0–1.1 m
Centred within the permitted range. Places pressure gauges at comfortable eye level and allows easy access to drain valve, alarm test valve, and OS&Y wheel handle.
Note that the height measurement is to the centreline of the valve body inlet — not to the top of the valve or to the OS&Y gate valve handwheel. For larger DN valves (DN200–DN300), the total height of the assembled alarm valve station (from inlet flange to the top of the OS&Y valve) can exceed 1.5–2.0 m — ensure the valve room ceiling height accommodates the full station assembly with clearance for handwheel operation.
Valve Room Requirements — GB 50084 & NFPA 13
Both codes specify requirements for the room or space where the alarm valve station is installed. These are frequently underspecified in early-stage building design, leading to costly rework when the fire protection consultant reviews the layout.
| Requirement |
GB 50084 Specification |
NFPA 13 Specification |
| Temperature |
≥ 4°C at all times — heating required in cold climates |
≥ 4°C (40°F) at all times |
| Floor drainage |
Floor drain required — sized for main drain valve full-flow discharge |
Drain or safe discharge point required for main drain and test connections |
| Lighting |
Permanent artificial lighting — sufficient for gauge reading and valve operation |
Adequate lighting for inspection and maintenance |
| Access |
Dedicated accessible room — lockable, accessible to fire service |
Accessible without removing finished construction |
| Clearance around valve |
Minimum 0.6 m in front of valve for inspection; 0.3 m sides |
Sufficient for inspection, testing, and maintenance without removing other components |
| Signage |
Zone identification sign on or adjacent to valve — identifies zone protected |
Each alarm valve station shall be identified with a permanently marked sign |
| Water motor gong discharge |
Gong mounted externally or discharge routed outside — audible from building exterior |
Gong audible from outside the structure |
Step-by-Step Installation Sequence
Follow this sequence for a flanged wet alarm valve installation. Dry alarm valve installation follows the same sequence with additional steps for the air-side components (noted separately).
1
Install OS&Y gate valve on supply mainMount the OS&Y isolation gate valve on the supply main, upstream of where the alarm valve will be positioned. Ensure the OS&Y valve is in the closed position before proceeding — the riser should be depressurised. Wire the tamper switch to the fire alarm control panel circuit (confirm continuity before proceeding).
2
Position alarm valve body on riserLift the alarm valve body into position on the riser. Confirm the flow direction arrow points upward. Confirm the alarm port is accessible for trim piping connection. Install flange gaskets (EPDM for water service; PTFE for aggressive environments). Insert flange bolts and hand-tighten.
3
Torque flange bolts in cross patternTighten flange bolts using a cross-tightening pattern (not circular) in three progressive torque stages — 30%, 70%, 100% of specified torque. Cross-tightening ensures even gasket compression and prevents leakage at one side of the flange face. Record final torque values in the installation documentation.
4
Connect supply pressure gaugeInstall the supply pressure gauge on the upstream (supply) side of the alarm valve body — typically on a tapping on the supply pipe between the OS&Y valve and the alarm valve inlet flange. Use a glycerine-filled gauge (0–1.6 MPa range) for vibration resistance. Install a gauge isolation valve (needle valve) between the pipe tapping and the gauge for future gauge replacement.
5
Connect system pressure gaugeInstall the system pressure gauge on the downstream (system) side of the alarm valve body. Same specification as the supply gauge. The differential between supply and system gauge readings in standby is the primary diagnostic indicator of clapper seal condition.
6
Connect alarm port trim — retard chamberConnect the G3/4 alarm port on the valve body to the retard chamber inlet using small-bore copper or stainless steel tubing (15mm OD typical). The retard chamber should be mounted at approximately the same height as the alarm valve body, accessible for inspection. Ensure the retard chamber drain connection discharges to a safe location that cannot cause damage or safety hazards.
7
Connect water motor alarm gongRun the alarm trim pipework from the retard chamber outlet to the water motor alarm gong. The gong should be mounted on the exterior wall of the valve room (or routed externally) so it is audible from outside the building. Install a small-bore shutoff valve between the retard chamber outlet and the gong for alarm test isolation. The gong drain pipe must discharge safely — not onto a walkway or into an electrical enclosure.
8
Connect alarm pressure switchInstall the alarm pressure switch on a tee in the alarm trim pipework — typically on the outlet side of the retard chamber, upstream of the gong connection. Run the 24VDC signal cable to the fire alarm control panel zone input. Test continuity of the cable run before commissioning.
9
Install main drain valveInstall the main drain valve on the system side of the alarm check valve body, downstream of the outlet flange. The main drain valve must be the same DN as the alarm valve. The drain discharge pipe must be routed to a safe location — typically a dedicated drain pit or building drainage system. The discharge point must be visible during the annual drain test.
10
Install inspector’s test valve (at most remote point)The inspector’s test valve is not installed at the alarm valve station — it is installed at the hydraulically most remote point in the sprinkler distribution system. This is typically at the end of the most remote branch line, on the highest floor or most distant zone from the alarm valve. The test connection must be sized to simulate a single open sprinkler head flow at the system’s minimum design pressure.
11
Install zone identification signMount a permanent, clearly legible zone identification sign at the alarm valve station — identifying the zone name/number, the area protected, and the DN size of the valve. Both GB 50084 and NFPA 13 require this signage as a condition of system acceptance.
Additional Steps for Dry Alarm Valve Installation
The ZSFC dry alarm valve installation follows all the steps above, plus the following air-side steps:
Air-Side Components to Install
- Pneumatic accelerator — mounted on the air-side trim pipework; factory-calibrated before shipment by CA-FIRE
- Air pressure maintenance device — small compressor or regulator; automatically maintains supervisory air pressure; prevents continuous manual recharging
- Low-air alarm pressure switch — on the system air side; signals FACP if air pressure drops below setpoint before valve trips
- System air pressure gauge — 0–0.5 MPa range (not 0–1.6 MPa) — displays supervisory air pressure
Air Pressure Setpoints
Supervisory pressure: 0.14–0.28 MPa (20–40 psi) — per NFPA 13
Low-air alarm setpoint: ~0.01 MPa below supervisory pressure
Accelerator trip setpoint: ~0.02–0.03 MPa below low-air alarm setpoint
Staggered setpoints: supervisory → low-air alarm → accelerator trip. This sequence ensures the FACP receives an early warning before the valve trips.
Pre-Commissioning Checklist — Before Opening the OS&Y Valve
Before slowly opening the OS&Y valve to pressurise the system for the first time, verify every item on this checklist. Pressurising a system with any item outstanding risks water damage, false alarms, or injury.
PRE-COMMISSIONING CHECKLIST
All flange bolts torqued to specification in cross pattern
Flow direction arrow on valve body confirmed pointing upward
Main drain valve confirmed CLOSED before initial pressurisation
All sprinkler heads installed in distribution pipework — no open pipe ends
Alarm trim pipework (retard chamber, gong, pressure switch) fully connected
Pressure switch cable run connected to FACP zone input, continuity confirmed
OS&Y tamper switch connected and generating supervisory signal at FACP when valve is closed
Gong drain pipe routed to safe discharge point — not onto a walkway or into an electrical area
Zone identification sign installed at valve station
Inspector’s test valve installed at most remote hydraulic point — confirmed and documented
First Pressurisation — Slow Fill Procedure
Pressurising a newly installed sprinkler system must be done slowly to avoid water hammer that can damage sprinkler heads, pipe joints, and the alarm valve clapper seal. Follow this sequence:
1
Open OS&Y valve slowly — one full turn every 30 seconds. Listen for water flow sounds in the distribution pipework. If the gong activates during filling, the alarm port retard chamber is filling with water from the initial pressurisation surge — this is normal for a dry empty system on first fill. It will stop once the system pressure equalises.
2
Monitor supply pressure gauge — as the system fills, the supply gauge pressure will initially rise to supply pressure, then stabilise. The system gauge will rise as water fills the distribution pipework. Both gauges should eventually read the same pressure when the system is fully charged.
3
Check for leaks at all connections — once both gauges equalise, walk the entire distribution system and inspect every flange, thread connection, and trim fitting for leaks. Mark any leaking connections for repair before commissioning.
4
Perform alarm trip test — open the inspector’s test valve for 60 seconds. Verify the water motor alarm gong activates within 90 seconds. Verify the FACP shows the zone alarm. Verify the fire pump starts (if applicable). Record test results in the commissioning documentation.
✓ NFPA 13 Acceptance Test Requirement
NFPA 13 requires a full system acceptance test before the system is placed in service. This includes a main drain test (full open drain flow with supply pressure recorded), an alarm trip test (inspector’s test valve with 90-second gong verification), and a complete visual inspection of all installed components. The AHJ must witness or receive documentation of the acceptance test before sign-off.
CA-FIRE Alarm Check Valve Range
Complete station assembly available — valve body, OS&Y valve, retard chamber, water motor gong, pressure switch, gauges, drain valve and inspector’s test connection pre-assembled and tested. DN32–DN300 · Flanged & Grooved · GB 5135.6 · NFPA 13 · Factory direct
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Alarm Check Valve Installation
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