Ductile Iron Flanged Wet-Type Alarm Valve ZSFZ Series

Product Description

The wet alarm valve assembly, together with a pressure switch, flow indicator, sprinkler heads, signal butterfly valve, end-of-line test device, and sprinkler pump, forms the ZS series wet automatic sprinkler system, which is currently the most widely used automatic sprinkler system.

Product Features

A wet alarm valve is an unidirectional valve that allows water to flow only in one direction into a sprinkler system and triggers an alarm when a specified flow rate is reached. It is used in wet fire suppression systems where the piping network is filled with water; such systems remain in a standby state at all times, with the piping network filled with pressurized water. In the event of a fire anywhere within the protected area, one or more sprinkler heads activate, and this valve automatically opens to allow water to flow continuously to the fire area. At the same time, the hydraulic alarm is activated, and the pressure switch sends an alarm signal.

How It Works

In a wet alarm valve, the water pressure on both sides of the valve disc is equal under normal conditions (water flows through the pressure-balancing orifices in the guide tube to maintain pressure equilibrium on both sides of the valve disc). Due to the valve disc's own weight and the difference in total water pressure on either side of the valve disc, the valve disc remains closed (the total pressure above the valve disc is greater than the total pressure below it). In the event of a fire, a closed-type sprinkler discharges water. Since the water pressure equalizing orifices in the guide tube cannot replenish the water fast enough, the water pressure upstream of the alarm valve drops. At this point, the water pressure upstream of the valve disc exceeds that downstream, causing the valve disc to open and supply water to the riser and piping system. Simultaneously, water flows through the annular groove of the alarm valve into the time-delay device, pressure switch, and hydraulic alarm, triggering a fire alarm signal and starting the fire pump.

When a fire occurs within the protected area of an automatic sprinkler system, the rising ambient temperature at the fire scene causes the glass bulb on the closed-type sprinkler to shatter (or the fusible alloy to melt), causing the sprinkler to open and discharge water to extinguish the fire. At this point, as the water pressure in the pipeline network on the outlet side of the wet alarm valve drops, a pressure differential is created. The valve disc assembly opens, allowing water from the water source to continuously replenish the pipeline network for fire suppression. Simultaneously, water flows through the holes in the sealing ring groove into the delay chamber, rapidly filling it. Under a certain water pressure, the water impacts the hydraulic alarm bell, triggering a continuous audible alarm. The pressure switch activates, closing its electrical contacts to connect to the control center, which then triggers audible and visual alarms. At the same time, the main water supply pump is started to support firefighting operations.

Functions of Wet-Type Alarm Valve Components

1. Wet-type alarm valve: Allows water to flow into the sprinkler system in only one direction and triggers an alarm when a specified flow rate is reached.
2. Delay device: Delays the activation of the hydraulic alarm to reduce false alarms caused by water pressure fluctuations.
3. Hydraulic alarm: A hydraulically driven alarm device that emits an audible signal when the system is activated.
4. Pressure switch: After the alarm valve activates, the pressure switch activates and closes the electrical contacts.
5. Alarm valve: This valve remains normally open when on standby; it may only be closed during inspection, maintenance, or repair.
6. Test alarm valve: Open this valve only during commissioning or maintenance to verify the system's operation.
7. Drain valve: Drains residual water from the piping system downstream of the valve to allow for maintenance or replacement of the nozzles.

Product Specifications

Product Size Guide