Fire protection valves and network components sit between the water supply and the sprinklers: control valves, alarm and check valves, flow and tamper switches, pressure gauges, test and drain connections, joints and hangers. In its 2026 sprinkler report, the National Fire Protection Association (NFPA) found that the most common reason sprinklers failed to operate was a system shut off before the fire. This guide explains what each does and what to check.
Key takeaways
- NFPA 13 requires control valves to be indicating and supervised open; NFPA 25 (2026 edition) requires them to be inspected weekly, monthly or quarterly, depending on how they are supervised.
- NFPA 25 requires a valve status test after any control valve is closed and reopened.
- Alarm valves, check valves and backflow preventers stop reverse flow; their interiors are inspected every 5 years.
- Flow switches tell the fire alarm panel that water is flowing; tamper switches tell it that a valve has moved off open.
- NFPA 13 (2025 edition) does not permit reconditioned valves and devices in new systems.
In this article
- Where the components sit in a water-based fire network
- Control valves and how they are supervised
- Alarm check valves, check valves and backflow preventers
- Flow switches and pressure switches
- Pressure gauges, test and drain connections
- Grooved, flanged and threaded joints, and pipe hangers
- Step-by-step: selecting and approving valves and components
- Common site mistakes, maintenance and cost
- How AZEIDK helps
- FAQ
Where the components sit in a water-based fire network
From the supply and fire pumps, the private underground main runs to the buildings, where a riser feeds the sprinkler piping. Each riser typically carries the main control valve, an alarm or check valve, pressure gauges, a waterflow device and a main drain. Hydrants and the fire department connection (FDC) are covered in our fire hydrants and landing valves guide.
| Component | What it does | What to check |
|---|---|---|
| Control valve | Opens or isolates the supply to a system or zone | Fully open; locked or supervised; signed |
| Tamper (valve supervisory) switch | Sends a supervisory signal when the valve moves off open | Operates early in valve travel; signal reaches the panel |
| Alarm check valve | Admits water to a wet system and triggers the waterflow alarm | Gauges above and below; no leaks |
| Check valve | Lets water flow one way only | Flow arrow correct |
| Waterflow switch | Sends an alarm signal when water flows | Retard setting; signal at the panel |
| Pressure gauge | Shows supply and system pressure | Reading in range; replaced or checked against a calibrated gauge every 5 years |
| Main drain and test connections | Drain the system; test the supply and alarms | Correct size; safe discharge point |
Control valves and how they are supervised
An outside screw and yoke (OS&Y) gate valve shows its position by its extended stem, an indicating butterfly valve by a pointer on its gear operator, and a post indicator operates a buried valve and shows its position in a window. NFPA 13 requires control valves to be indicating, meaning their position is easy to see, per Section 16.9.3.2 of NFPA 13 (2022 edition).
| Type | How it shows position | Typical use | Notes |
|---|---|---|---|
| OS&Y gate | Extended stem | Pump rooms, main control valves | Needs space for stem travel; flanged or grooved ends |
| Indicating butterfly | Pointer on the gear operator | Risers, floor control assemblies | Compact; often a built-in supervisory switch |
| Post or wall post indicator | Window showing open or shut | Underground valves outside buildings | Protect from vehicle impact |
A shut valve silently disables everything downstream, so NFPA 13 requires control valves to be supervised open, by locks and seals or by tamper switches monitored at the fire alarm panel; the NFPA 13 Handbook prefers central station monitoring. The NFPA report U.S. Experience with Sprinklers (2020–2024 data) names a system shut off before the fire as the most common reason sprinklers failed to operate.
The Potter PCVS datasheet, for example, states that a tamper switch must operate within the first two revolutions of the handwheel or one-fifth of the valve travel. NFPA 25 (2026 edition) requires these switches to be inspected quarterly and tested semiannually.
Alarm check valves, check valves and backflow preventers
The alarm check valve sits at the base of a wet riser. When a sprinkler opens, its clapper lifts and water reaches the alarm line, operating a pressure switch or water motor gong; a retard chamber can limit false alarms. Dry pipe, pre-action and deluge valves are covered in our wet, dry, pre-action and deluge systems guide.
NFPA 13 (2025 edition) requires a check valve in each connection where an FDC is installed or there is more than one water supply, so that one source cannot drain into another. A backflow preventer protects the public water supply where the water authority requires one. NFPA 25 (2026 edition) requires alarm valve exteriors to be inspected quarterly and interiors every 5 years, check valve interiors every 5 years, and backflow assemblies to be tested annually.
Flow switches and pressure switches
A vane-type waterflow switch has a paddle inside the pipe that moves when water flows, with an adjustable retard to ignore short surges; the TYCO Model TF, for instance, serves wet pipe systems with a 0 to 90 second delay. On alarm check valves, a pressure switch on the alarm line does the same job.
The NFPA 13 (2022 edition) rules include: a local waterflow alarm on every system with more than 20 sprinklers, no paddle-type flow switches on dry pipe systems, and a flow switch on every floor of high-rise buildings. NFPA 25 (2026 edition) requires waterflow devices to be tested quarterly or semiannually, with vane-type devices kept in service during testing unless impairment procedures are followed.
Pressure gauges, test and drain connections
NFPA 13 requires approved gauges at defined points, such as both sides of a dry pipe valve. NFPA 25 requires gauges to be replaced, or tested against a calibrated gauge, every 5 years.
The main drain test compares static and residual pressure with earlier results; a large drop points to a partly closed valve or an obstruction. NFPA 13 sizes main drain connections by riser size: 3/4 in. (20 mm) or larger for risers up to 2 in., and 2 in. (50 mm) for risers of 4 in. and larger. For dry systems, the 2025 edition requires a test connection of at least 1 in. (25 mm), ending in a smooth-bore orifice that flows like one sprinkler.
Grooved, flanged and threaded joints, and pipe hangers
Grooved couplings clamp a housing and gasket onto grooved pipe ends, so they install quickly and come apart easily. Rigid couplings lock the joint; flexible couplings allow some movement for thermal or seismic needs, with matching support. Flanges suit pumps, valves and large mains, and threaded joints small sizes. Use components listed for the system pressure and follow the manufacturer’s instructions for gaskets and bolt tightening.
Chapter 17 of NFPA 13, as revised for the 2025 edition, sets minimum hanger rod sizes, such as 3/8 in. (10 mm) rod for pipe up to 4 in. (100 mm), and maximum distances between supports.
Step-by-step: selecting and approving valves and components
- Confirm the adopted NFPA 13 edition, the system pressure and the approved hydraulic design.
- Check the listing or approval of the exact model, not the brand, as our UL Listed vs FM Approved guide explains.
- Match pressure rating, size, end connections and orientation to the design.
- Confirm that each supervisory switch suits its valve and the fire alarm panel.
- Ask for datasheets, and check whether the item falls under a technical regulation of the Saudi Standards, Metrology and Quality Organization (SASO) that requires registration on the SABER platform.
- Reject reconditioned valves and devices for new systems.
- Plan access: reachable valves, readable gauges, safe drain discharge and signed valves.
- At acceptance, run the hydrostatic test: the 2022 edition of NFPA 13, requires piping to hold 200 psi (13.8 bar) for 2 hours, or 50 psi (3.4 bar) above working pressure where that exceeds 150 psi (10.3 bar). Then operate every valve and test every switch.
Common site mistakes, maintenance and cost
- Valves left closed or partly closed after work, with no valve status test.
- Tamper switches disconnected or mounted where they cannot detect valve movement.
- Alarm or check valves installed against the flow arrow.
- Gauges never replaced, and drains with no safe discharge, so tests are skipped.
- Hangers removed by other trades, and couplings with the wrong gasket.
NFPA 25 also requires control valves to be operated annually and OS&Y valves maintained annually. The full schedule is in our NFPA 25 guide. Cost follows the number of risers and zones, valve sizes and types, the approval route, supervision wiring, the joining method, and testing and documentation.
How AZEIDK helps
Through its fire fighting systems solutions, AZEIDK covers sprinkler networks, pumps, valves and pipes. Our technical selection of systems and equipment service reviews datasheets and verifies each device against the approved specification, and our annual maintenance contracts include periodic inspections and functional tests. See also our owner’s guide to fire sprinkler systems and NFPA 13 guide.
Brands within our supply scope include American Fire Control (AFC) for fire network components, among them OS&Y flanged and grooved gate valves (Models A-3000 and AG-3000), the ACV-300 Series wet alarm valve and a vertical post indicator (Model 5100), and KD Industries (KDI) UL Listed and FM Approved pipes in Schedule 10 and 40. We recommend verifying each model’s approval in its datasheet.
FAQ
What is the difference between an OS&Y valve and a butterfly valve?
Both are indicating control valves. An OS&Y gate valve shows its position by the extended stem and needs room for stem travel, so it is common in pump rooms. An indicating butterfly valve uses a pointer, is more compact and often has a built-in supervisory switch, so it suits risers and floor assemblies.
What does a tamper switch do?
It sends a supervisory signal to the fire alarm panel when a control valve moves off open, so a closed valve is found before it becomes a hidden failure. Datasheets such as Potter’s require early operation, and NFPA 25 (2026 edition) requires it to be tested semiannually.
How often should fire protection control valves be inspected?
Under NFPA 25 (2026 edition): weekly if neither locked nor supervised, monthly if locked or supervised, and quarterly if electrically supervised, plus an annual operation test and a valve status test after any reopening. The Saudi Fire Protection Code (SBC 801) and Civil Defense set the applicable edition.
Why does a sprinkler network need check valves?
To stop water flowing from one supply into another or back toward the source. NFPA 13 (2025 edition) requires a check valve in each connection where a fire department connection is installed or there is more than one water supply, and NFPA 25 has their interiors inspected every 5 years.
Which is better, grooved or flanged joints?
Neither is better in every case. Grooved couplings install faster and come apart easily, and flexible types allow some movement, while flanges suit pumps, valves and large mains. What matters is listing for the system pressure and installation to the manufacturer’s instructions.
Need your network valves and components reviewed? Send us your drawings or latest inspection report, and our engineers will review the valves, supervision and tests required. Contact the AZEIDK team
