Alarm Check Valves

Perform a 2-inch drain test quarterly to test alar m check valves. Open the 2-inch drain valve fully and record pressure on the gauge located below the clapper at the lowest point. Close the 2-inch drain valve and record pressure at the stabilization point. Notice whether pressure returns quickly or slowly. Maintain a continuous record of drain tests. If recorded pressure when the valve is wide open is similar to previous recordings and pressure returns quickly, it is normal.

If recorded pressure when the valve is wide open is significantly lower or pressure is slow to return when the valve is closed, there may be an obstruction in the waterway. Check for the following problems:

. Partially closed valves to sprinkler system . Obstruction in alarm valve preventing clapper from opening freely

Test local water-flow alarm operation monthly by opening the test connection at the end of the system. Where there is no test connection, the alarm may be tested by opening the bypass valve to the circuit opener or closer or by opening the 2-inch drain valve about two and one-half turns. Do not test water motor alarms during freezing weather. To find principal causes of alarm failures, check for the following: 

. Failure of automatic drain on retard chamber to close

. Closed or partially closed valve on piping to alarm devices . Plugging of bell casings of water motor gongs by foreign material l Corrosion of moving parts of water motor gongs

. Detachment of shaft couplings from water motor gongs

. Insufficient water flow to operate devices . Alarm check valve corroded shut (this failure is not common and will not occur when systems are properly maintained) To find principal causes of false fire alarms, check for the following:

. Improper drainage of retard chamber (correct this by opening the chamber and cleaning or repairing the automatic drain)

. Pressure surges through the alarm check valve

Fill wet pipe sprinkler systems slowly through throttled valves and open the control valve wide after the system has been filled. Be sure there is no drainage from retard chambers. Leakage means that the alarm valve clappers are not seating properly. They require cleaning and possibly overhauling.

Make internal inspections of alarm valves when normal testing procedures indicate the need.

l Examine valve body for tuberculation.

l Check clapper operation-the clapper should move freely without sticking or binding.

l Replace clapper facings as required.

l Resurface seat rings as required.

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