Fire Sprinkler System Guide

Fire Sprinkler System Valves: A Complete Guide (Wet, Deluge & Pre-action)

Every sprinkler system is built around a control valve assembly — the point where the water supply becomes the fire suppression system. Specify the wrong valve type and the entire system logic fails inspection. This guide explains the four valve types that dominate modern fire sprinkler design, what each one does, and the occupancy types they protect. For the isolation and section-control valves around the assembly — OS&Y gate, signal butterfly and check valves — read our fire sprinkler control valve types guide.

Wet Alarm Check Valve (ZSFZ-150)

Wet-pipe alarm valve with flow detection and alarm trip

Deluge Alarm Valve Group (ZSFM Series)

Diaphragm-operated deluge valve for high-hazard occupancy

Pre-action Deluge Alarm System (ZSFY Series)

Dual-trigger failsafe pre-action valve for water-sensitive zones

Vane Type Water Flow Indicator (ZSJZ Series)

Zone flow detection with adjustable delay for wet sprinklers

1. Wet-Pipe Systems: The ZSFZ Wet Alarm Valve

Wet-pipe systems are the most common sprinkler configuration: the piping is permanently charged with water, and each sprinkler head opens individually when its heat-sensitive element bursts. The ZSFZ wet alarm check valve sits at the system riser and performs two duties: it prevents reverse flow from the system back into the supply, and it detects the water flow created when a head opens, tripping the mechanical and electrical alarms. Flow continues into the system until the supply is shut off manually.

Wet systems are fast, simple and cheap to maintain — but they cannot be used where ambient temperatures risk freezing the piping.

2. Deluge Systems: The ZSFM Deluge Valve

Deluge systems protect high-hazard occupancies where fire can spread faster than individual sprinkler heads can respond: chemical plants, paint shops, power stations, aircraft hangars. All nozzles in a deluge zone are open, and the system is held back by a single control valve — the ZSFM deluge alarm valve. When a detection system (smoke/heat/flame) signals a fire, the valve opens and water floods every nozzle simultaneously.

The diaphragm-operated ZSFM opens fast and reseals reliably after operation, which matters because deluge zones are often large and the valve is the single point of failure in the system.

3. Pre-Action Systems: The ZSFY Dual-Trigger Valve

Pre-action systems are deluge hardware with a sprinkler-pipe twist: the piping is dry, and water only enters after two independent triggers confirm a fire. The ZSFY pre-action alarm system is the control assembly for this architecture — a deluge-type valve operated by a fire detection signal, with automatic sprinklers downstream that also act as individual fuses.

Why specify pre-action? Three reasons dominate:

• Water-sensitive contents — museums, archives, data centres, transformer rooms: no water enters unless two signals confirm.
• Freezing environments — cold storage, unheated warehouses: dry piping cannot freeze.
• False-discharge insurance — the dual-trigger logic makes accidental discharge statistically negligible.

4. Zone Detection: The ZSJZ Water Flow Indicator

Once the system is operating, the fire brigade and the building manager need to know which zone is flowing. The ZSJZ vane water flow indicator installs on sprinkler branch lines: when water moves, the vane deflects and the switch sends a signal to the alarm panel identifying the affected zone. An adjustable time delay filters out pressure surges that would otherwise cause nuisance alarms.

5. Selecting the Right Valve for Your Project

A complete assembly typically pairs the alarm valve with a signal gate valve upstream, a check valve, gauges and the alarm trim. When you send us your hazard class and pipe size, we quote the full valve assembly rather than a single valve — one certified package, one set of documents.

Frequently Asked Questions