Potter Releasing Systems - Manual (Page 36)

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Test Procedures
Waterflow Switches - Wet Pipe Systems
Vane Type
There should be a valve downstream of the flow switch, preferably at the far end of the system, but it may be
immediately after the flow switch. The valve should be marked Inspectors Test Valve per NFPA13 2010 6.7.4.1.
The valve should also have a reduced orifice equal to the smallest sprinkler on the system per NFPA13 2010
8.17.4.2.1. The output of the valve should be piped to a spot where it will not cause any water damage.
Open the valve and allow the water to flow, after the retard time expires, the switch will trip. If the device does
not operate check to make sure 10 gpm is flowing out of the test valve. If possible, place a 5 gallon bucket under
the output of the valve. If the bucket can be filled in 30 seconds then the valve is flowing 10 gpm.
If a hose needs to be connected to the test valve to prevent water damage, the hose should be 5/8” ID, and as
short as possible to reduce friction loss.
If the device still does not trip it may be installed too close to a valve or change in direction of pipe which is
causing turbulence or back pressure in the water, or paddle may have been trimmed. Never trim the paddle.
Pressure Type
The preferred method is to open the inspectors test valve at the end of the system similar to the method for test-
ing vane type flow switches. This test also causes the clapper of the alarm valve to open.
Another test method is to open the normally closed alarm by-pass valve that connects the supply water directly
to the pressure switch. This is usually a 1/2” or 3/4” ball valve. On most systems there will be two ball valves
between the pressure switch and the alarm valve. One of these is the normally closed by-pass valve that is only
opened for testing. The other valve is a normally open alarm shut off valve. It is used to either silence the pres-
sure switch in an actual alarm or to disable it if water must be flowed into the system.
The pressure switch should be installed on top of a retard chamber or a pressure switch with a built-in retard
should be used. If the switch is installed on top of the retard chamber, it will activate as soon as the retard
chamber fills. The time delay provided by a retard chamber will vary depending on the water supply pressure at
the time. The time delay provided by a pressure switch with a built-in retard will remain constant. As long as the
pressure at the switch is at least 6 psi, the switch will trip after the retard times expires.