In a wet pipe sprinkler system, which measurement is indicated by the gauge located above the clapper of the alarm valve?

In a wet pipe sprinkler system, which measurement is indicated by the gauge located above the clapper of the alarm valve?

• A. Fire system pressure
• B. Operating pressure
• C. System pressure
• D. Downstream pressure

Answer: (C)

In a wet-pipe system, the gauge mounted above the alarm valve’s clapper is tied to the system side and shows the pressure inside the sprinkler piping that is being protected. This is called the system pressure—the actual water pressure within the piping after the valve and before any sprinklers release water. It isn’t the supply’s overall fire system pressure, nor the pressure required to operate the valve (operating pressure), nor a downstream pressure after another device. The gauge above the clapper tells you the pressure the system itself is holding.

In a wet-pipe system, the gauge mounted above the alarm valve’s clapper is tied to the system side and shows the pressure inside the sprinkler piping that is being protected. This is called the system pressure—the actual water pressure within the piping after the valve and before any sprinklers release water. It isn’t the supply’s overall fire system pressure, nor the pressure required to operate the valve (operating pressure), nor a downstream pressure after another device. The gauge above the clapper tells you the pressure the system itself is holding.