ZSFZ Wet Alarm Valve

ZSFZ Wet Alarm Valve

Execution Standard: GB5135.2-2003

Model Specifications: DN100, DN150, DN200, DN250

Rated Working Pressure: 1.2MPa, 1.6MPa

I. Purpose of ZSFZ Wet Alarm Valve:

The wet alarm valve, when connected with a retarder, water motor gong, etc., forms a wet alarm valve assembly. It is one of the key components in a wet automatic sprinkler system, remaining in the ready state for long periods, serving to supply water for firefighting and provide direct alarm.

II. Working Principle and Features of ZSFZ Wet Alarm Valve:

In the ready state of the automatic sprinkler system, the entire pipe network is filled with pressurized water as per design requirements, and the wet alarm valve clapper closes due to its own weight. In the protected area of the wet system, once a fire occurs, the heat activates the closed sprinkler head, initiating water discharge for firefighting. This causes a drop in water pressure on the pipe network side of the wet alarm valve, creating a pressure difference between the upper and lower chambers of the clapper. When the pressure difference reaches a certain level, the water flow impact opens the clapper, supplying water for firefighting (normally, personnel can periodically use the end test valve or the drain valve of the alarm valve for water discharge alarm tests). Simultaneously, part of the water flow enters the annular groove exposed after the clapper opens, passes through the alarm pipeline and retarder, and enters the gong, causing the water motor gong to sound an alarm. At the same time, the pressure switch activates, transmitting an electrical signal to the alarm control center to trigger audible and visual alarms, and starts the fire pump to continue supplying water to the pipe network for firefighting.

If a sprinkler head activates or an end water discharge test is conducted, the flowing water can first activate the water flow indicator and transmit the signal to the fire control center to display an alarm.

The alarm valves produced by our company include 1.2MPa and 1.6MPa working pressure series of externally balanced alarm valves. The external balancing technology is more advanced, improved from internal balancing, overcoming alarm valve gap alarm failures caused by poor water quality (e.g., high mud content) and facilitating maintenance when pressure difference balancing fails. Externally balanced alarm valves feature advanced technology, excellent sealing performance, and sensitive, reliable operation. The externally balanced valve body is made of HT250 or QT cast iron, while the valve seat, clapper, connecting rod, and all control valve filters are made of corrosion-resistant materials such as brass and stainless steel, ensuring long service life.

III. Main Components and Functions of ZSFZ Wet Alarm Valve:

1. Water Supply Control Valve (No. ☆): Mainly controls the opening or closing of the water source, serving to cut off flow and display the cut-off signal [if specified in the order, our company provides fire signal butterfly valves (only signal valves) as accessories].

2. Wet Alarm Valve (No. 1): A check valve that allows water to flow into the wet firefighting system and drives accessories (gong, pressure switch) to alarm under specified pressure and flow.

3. Alarm Pipeline Valve (No. 7): Remains normally open in both standby and working states; can only be closed for inspection, maintenance, or repair.

4. Retarder (No. 8): Its function is to minimize false alarms caused by water source pressure fluctuations or impacts.

5. Pressure Switch (No. 9): When the water motor gong alarms, water pressure activates the pressure switch to connect electrical contacts, remotely transmitting the alarm valve action information to the control center.

6. Water Motor Gong (No. 10): An alarm device that produces sound when driven by water flow after the wet alarm valve activates.

7. Drain Valve (No. 5): Normally closed in standby and working states; used only for draining pipe network water during alarm valve maintenance or closed sprinkler head replacement. Opening this valve can also perform an action alarm test (clapper can open).

8. Pressure Gauge (No. 2, No. 4): Determines the water pressure condition of the alarm valve.

9. Pressure Gauge Adapter (No. 12): Converts metric threads to imperial threads for installing pressure gauges.

10. Retarder Pressure Maintenance Adapter (No. 11): A specific adapter used to maintain certain working pressure and drain water for the water motor gong and retarder (must not be lost or arbitrarily replaced).

11. Alarm Test Valve (No. 6): When the alarm valve is in the ready state, manually opening this valve without activating the clapper allows testing the alarm device (gong, pressure switch) functionality using water flow from the supply side. This is a newly added component in the product standard and a mandatory key inspection item per GB588-0-2005 on-site fire product inspection rules.

IV. Design, Installation, and Commissioning Notes for ZSFZ Wet Alarm Valve:

1. Design:

A. The wet alarm valve system pipe network must not contain air; otherwise, intermittent gap alarms may occur during alarm valve water discharge tests. Therefore, designers should include measures such as automatic exhaust valves in the system design.

B. The drain valve of the alarm valve system, as well as the drain outlets of the water motor gong and retarder, can be individually connected to drain pipes based on the environment. Contractors often connect them to the same drain pipe for aesthetics, which is not allowed as circulating pressure water can cause gong leakage or damage.

2. Installation:

A. Before installation, the water supply pipe section connected to the alarm valve must be flushed to remove impurities until clear water flows out. The flushing flow should not be less than the system design flow.

B. The alarm valve system should be concentrated on the ground floor or basement of the building, with an ambient temperature of 4-70°C. The main valve should be about 1.2m above the floor, with at least 0.5m clearance on both sides and 1.2m clearance in front for easy operation.

C. For alarm valve assemblies delivered to the destination (company or site) by the manufacturer, all pipe fittings pre-assembled and fixed by the manufacturer have undergone 100% 2.4MPa sealing tests before leaving the factory; users must not disassemble them.

D. Our company's alarm valves use advanced external balancing; users are strictly prohibited from disassembling the check valve (external balance valve) used to maintain pressure balance between the upper and lower parts of the valve assembly.

3. Commissioning:

Open the water supply valve (No. ☆) and slowly fill the system pipeline with water until design pressure is reached. The system is now in the ready state. The alarm pipeline valve (No. 7) is in the normally open position. Open the drain valve (No. 5) for continuous water discharge. Once the alarm valve clapper opens automatically due to pressure difference, water flows into the retarder (No. 8). After a delay of 5-90 seconds, the water motor gong should sound an alarm, the pressure switch should activate, and the control system should display the alarm signal. Confirm normal operation, then close the drain valve to complete the commissioning.

V. Testing, Inspection, and Fault Diagnosis of ZSFZ Wet Alarm Valve:

The wet alarm valve should be tested periodically by opening the drain valve (No. 5) for alarm tests, with water discharge tests conducted at least quarterly. If unused for extended periods, the alarm valve and other system products may develop abnormalities due to stagnant water. To check only the functionality of the gong and pressure switch, open the alarm test ball valve (No. 6).

Common issues during alarm valve commissioning and use:

1. Continuous Alarm: When the alarm valve triggers an alarm automatically and continuously without water discharge减压 and with the alarm pipeline valve (filter ball valve) open, this abnormality is usually due to uncleaned pipes with debris or杂物 preventing the clapper from sealing. The solution is to remove the debris.

2. Intermittent Alarm: During water discharge tests, intermittent gap alarms may occur due to excessive air in the fire pipe network. Eliminating this phenomenon requires removing as much air as possible.

3. Slow Alarm: During water discharge tests, alarms may not occur immediately, sometimes taking over ten minutes or even twenty to thirty minutes. This often happens in projects with many controlled floors and large sprinkler pipe networks, where pressure differences form slowly. Generally, larger systems with more sprinkler heads result in slower alarm valve activation, which is normal. Many believe the alarm valve delay time is 5-90 seconds, which refers to the time after the alarm valve activates (clapper opens) for water to flow from the alarm outlet through the alarm pipeline into the retarder before the gong and pressure switch activate (as required by standard).

4. No Alarm: If the alarm valve does not alarm during water discharge tests, first confirm if there is sufficient constant pressure water source and if control valves are unobstructed; second, check if the alarm pipeline (especially the alarm outlet and retarder inlet), gong inlet, and other small orifices are clogged with impurities. If the pipe network side pressure gauge shows higher pressure than the inlet side, the pressure difference cannot form quickly, making it harder for the alarm valve to alarm.

VI. Maintenance and Care of ZSFZ Wet Alarm Valve:

1. If abnormalities occur, inspect the sealing ring groove holes, filters, retarder inlet, overflow outlet, water motor gong inlet, etc., for blockages like mud, iron chips, or dirt, and clean them promptly if found.

2. The alarm valve and its accessories should be inspected and tested on-site using the drain valve at least quarterly to ensure safe and reliable operation. Water discharge tests should be conducted using the end valve every three months.