The water motor gong of the wet alarm valve does not operate or its sound is insufficient; after the sprinkler system activates, it fails to effectively emit an alarm signal.
The wet alarm valve is a key component of the automatic sprinkler system, issuing an alarm signal and starting the fire pump after a sprinkler head activates. The working principle is that in the servo state, the upper and lower water pressures on the valve clack balance and the clack remains closed; after a sprinkler head activates, the water pressure in the pipe network drops, the clack opens and water flows to the sprinkler head, while water simultaneously enters the alarm pipe to drive the water motor gong to sound and trigger the pressure switch. Section 6.2 of GB 50084-2017 specifies requirements for the design of alarm valve assemblies.
The alarm valve is installed in the fire pump room or a dedicated alarm valve room with an ambient temperature not lower than 4°C. The center of the alarm valve is 1.2 m above the floor, with an operating space of not less than 0.8 m. Drainage facilities are provided below, with a drain pipe of DN75 or above. The number of sprinkler heads controlled by each alarm valve shall not exceed 800. Signal feedback: the valve open status is fed back to the fire control room. The water motor gong is installed no more than 25 m from the alarm valve.
The sound pressure of the water motor gong is required to be not less than 70 dB at 3 m to ensure it is heard by duty personnel. The gong water pipe is galvanized steel pipe DN15 to 20. A 40-mesh strainer is provided at the inlet to prevent blockage by debris. The retard chamber prevents false alarms caused by fluctuations in pipe network water pressure, with a delay time of 18 to 40 seconds. A small orifice of approximately 4.8 mm is provided at the bottom of the retard chamber for drainage.
Pipes shall be flushed before construction and installation. Functional tests shall be carried out after installation, including the valve clack opening test, gong test and pressure switch test. During commissioning, open the end-of-line test device at the most unfavorable point to check the alarm valve operation and signal feedback. Check the alarm valve appearance, signal valve status and pressure gauge readings monthly. Open the end-of-line test valve quarterly to test the alarm valve operation and gong. Clean the strainer and check the valve clack sealing surface every six months. Dismantle for inspection and replace seals annually.
Common problems include the alarm valve failing to operate due to a stuck clack or blocked compensator, frequent false alarms due to pipe network pressure fluctuations or a blocked retard chamber drain orifice, the water motor gong not sounding due to a blocked strainer or stuck impeller, the pressure switch failing to operate due to poor contact or an aged diaphragm, and valve clack leakage due to an aged sealing gasket or scratches on the sealing surface. Troubleshooting should proceed from simple to complex: first check the valve open status, then dismantle and inspect internal components.
The alarm valve room should have a floor drain to prevent water from flooding the pump room during testing. The water motor gong should preferably be located outside the alarm valve room and close to the duty area so that the alarm can be heard easily. The end-of-line test pipe drains into a dedicated drain pipe and shall not discharge directly into the domestic sewage system. The alarm valve drain pipe should preferably be routed outdoors or to the drainage system and shall not discharge into the building interior.
The focus of wet alarm valve maintenance management in hotels is to prevent false alarms and ensure reliable operation. The alarm valve room should be kept clean and dry, with the temperature controlled within the range of 4 to 40°C. Regular cleaning of the retard chamber and strainer is a key measure to prevent false alarms, at least once per quarter. The sound test of the water motor gong should be included in the monthly fire facility inspection to ensure the gong can be clearly heard in all areas of the hotel. The linkage test of the pressure switch is carried out quarterly, and the test results are recorded in the alarm valve assembly maintenance log. A valve locking device should be installed on the inlet signal valve of the alarm valve assembly to prevent accidental closure, and an electronic monitoring module should be provided to feed back the valve status to the fire control room in real time. For hotel buildings with multiple alarm valve assemblies, the control area of each alarm valve assembly should be clearly marked on the assembly to facilitate quick locating and operation by maintenance personnel.
Wet alarm valve maintenance management also needs to address seasonal issues of the system. In northern regions with low winter temperatures, heating facilities should be provided in the alarm valve room to ensure the ambient temperature is not lower than 4°C and prevent the alarm valve assembly from freezing. In humid southern regions, dehumidification of the alarm valve room is equally important; excessive humidity will cause corrosion of alarm valve components and electrical faults. The quarterly testing of alarm valve assemblies should be developed into standardized operating procedures executed by trained operators. The test content includes opening the end-of-line test valve to simulate sprinkler head activation, observing the opening of the alarm valve clack, measuring the sound level of the water motor gong, and recording the pressure switch actuation time and signal feedback status. Comparative analysis of test data with historical data can reveal deterioration trends in system performance. The electronic monitoring function of the inlet signal valve of the alarm valve assembly should be checked monthly to ensure that the fire control room receives an alarm signal promptly when the valve is accidentally closed. Repair and replacement of alarm valve assemblies shall be undertaken by qualified professional units, and functional tests shall be re-performed after repair to ensure system performance is restored to the design state. Through standardized maintenance management, the wet alarm valve assembly is ensured to remain in a sensitive and reliable working state, providing a strong guarantee for building fire safety.
Wet alarm valve maintenance management also needs to address seasonal issues of the system. In northern regions with low winter temperatures, heating facilities should be provided in the alarm valve room to ensure the ambient temperature is not lower than 4°C and prevent the alarm valve assembly from freezing. In humid southern regions, dehumidification of the alarm valve room is equally important; excessive humidity will cause corrosion of alarm valve components and electrical faults. The quarterly testing of alarm valve assemblies should be developed into standardized operating procedures executed by trained operators. The test content includes opening the end-of-line test valve to simulate sprinkler head activation, observing the opening of the alarm valve clack, measuring the sound level of the water motor gong, and recording the pressure switch actuation time and signal feedback status. Comparative analysis of test data with historical data can reveal deterioration trends in system performance. The electronic monitoring function of the inlet signal valve of the alarm valve assembly should be checked monthly to ensure that the fire control room receives an alarm signal promptly when the valve is accidentally closed. Repair and replacement of alarm valve assemblies shall be undertaken by qualified professional units, and functional tests shall be re-performed after repair to ensure system performance is restored to the design state. Through standardized maintenance management, the wet alarm valve assembly is ensured to remain in a sensitive and reliable working state, providing a strong guarantee for building fire safety. Commissioning of the wet alarm valve is a key step before system acceptance. Before commissioning, confirm that pipe flushing and pressure testing have passed and the water supply is normal. During commissioning, first open the gong test valve of the alarm valve to check whether the water motor gong sounds normally and whether the pressure switch operates. Then close the gong test valve and open the end-of-line test valve to simulate sprinkler head activation, observe whether the alarm valve clack opens normally, whether the water motor gong sounds, and whether the pressure switch operates and feeds back a signal to the fire control room. Record the opening time of the alarm valve and the actuation time of the pressure switch, and check whether the retard chamber drains properly. During commissioning, attention should be paid to changes in the readings of the pressure gauges on the upper and lower chambers of the alarm valve to confirm good clack sealing. If abnormalities are found, identify the cause and adjust or repair. The commissioning record shall document in detail the commissioning results of each alarm valve assembly and the confirmation signatures. Only after successful commissioning may system linkage testing and acceptance proceed. The annual maintenance plan for wet alarm valves should include monthly inspection, quarterly testing, semi-annual cleaning and annual dismantling inspection; the content of each inspection and test shall be executed in accordance with the requirements of GB 50261-2017, and records shall be kept for not less than 5 years.
Commissioning of the wet alarm valve is a key step before system acceptance. Before commissioning, confirm that pipe network flushing and pressure testing have passed and that the water supply is normal. During commissioning, first open the alarm valve's test alarm bell valve to check whether the hydraulic alarm bell rings normally and whether the pressure switch actuates. Then close the test alarm bell valve and open the end test water valve to simulate sprinkler actuation, and observe whether the alarm valve clapper opens normally, whether the hydraulic alarm bell rings, and whether the pressure switch actuates and feeds a signal back to the fire control room. Record the alarm valve opening time and the pressure switch actuation time, and check whether the retard chamber drains normally. During commissioning, pay attention to the changes in the readings of the pressure gauges on the upper and lower chambers of the alarm valve to confirm that the clapper seals well. The commissioning record shall document in detail the commissioning results of each alarm valve assembly and the confirmation signatures. The annual maintenance plan for the wet alarm valve shall include monthly inspection, quarterly testing, semi-annual cleaning and annual disassembly inspection; the content of each inspection and test shall be carried out in accordance with the requirements of GB 50261-2017, and records shall be kept for no less than 5 years. The clapper sealing rubber gasket of the wet alarm valve shall be replaced every 3 years to prevent leakage caused by aging. The accuracy of the pressure gauges on the upper and lower chambers of the alarm valve shall be calibrated once a year to ensure accurate readings. Fault diagnosis of the wet alarm valve requires a systematic troubleshooting method. Common causes of the alarm valve failing to actuate include the clapper being stuck by debris, damage to the check valve of the compensator, or imbalance of pressure between the upper and lower chambers. Common causes of frequent false alarms include blockage of the retard chamber drain hole, excessive fluctuation of pipe network pressure, or poor sealing of the clapper. Common causes of the hydraulic alarm bell not ringing include blockage of the strainer at the alarm bell inlet, insufficient water pressure to the alarm bell, or jamming of the impeller. Common causes of the pressure switch failing to actuate include poor contact of contacts, aging of the diaphragm, or loose wiring. Establish a fault case library for maintenance personnel to refer to and learn from, so as to improve maintenance efficiency.
The clapper sealing rubber gasket of the wet alarm valve shall be replaced every 3 years to prevent leakage caused by aging. The accuracy of the pressure gauges on the upper and lower chambers of the alarm valve shall be calibrated once a year to ensure accurate readings. Fault diagnosis of the wet alarm valve requires a systematic troubleshooting method. Common causes of the alarm valve failing to actuate include the clapper being stuck by debris, damage to the check valve of the compensator, or imbalance of pressure between the upper and lower chambers. Common causes of frequent false alarms include blockage of the retard chamber drain hole, excessive fluctuation of pipe network pressure, or poor sealing of the clapper. Common causes of the hydraulic alarm bell not ringing include blockage of the strainer at the alarm bell inlet, insufficient water pressure to the alarm bell, or jamming of the impeller. Common causes of the pressure switch failing to actuate include poor contact of contacts, aging of the diaphragm, or loose wiring. Systematic fault diagnosis and experience accumulation are key to improving maintenance efficiency; it is recommended to establish a fault case library for maintenance personnel to refer to and learn from. Through standardized processes and professional operations, system maintenance management ensures that the wet alarm valve assembly remains in a sensitive and reliable working state over the long term, providing assurance for the normal operation of the building's fire sprinkler system.
Fault diagnosis of the wet alarm valve requires systematic troubleshooting methods and accumulated experience. Common causes of the alarm valve failing to actuate include the clapper being stuck by debris, damage to the check valve of the compensator, or imbalance of pressure between the upper and lower chambers. Common causes of frequent false alarms include blockage of the retard chamber drain hole, excessive fluctuation of pipe network pressure, or poor sealing of the clapper. Common causes of the hydraulic alarm bell not ringing include blockage of the strainer at the alarm bell inlet, insufficient water pressure to the alarm bell, or jamming of the impeller. Common causes of the pressure switch failing to actuate include poor contact of contacts, aging of the diaphragm, or loose wiring. Establishing a fault case library for maintenance personnel to refer to and learn from can significantly improve maintenance efficiency. Standardized maintenance management of the wet alarm valve, through monthly inspection, quarterly testing, semi-annual cleaning and annual disassembly inspection, ensures its long-term sensitivity and reliability.