FPS-SIP0
The Pre-action system is a fire protection (FP) combined system, consisting of a controlled FDV deluge valve and a riser check valve installed downstream. The pressurized automatic sprinkler pipeline keeps the riser check valve closed. The section between the downstream side of the closed deluge valve and the check valve clapper serves as the “intermediate chamber,” where the water pressure switch and acoustic alarm are connected.
In Single-interlock pre-action systems, such as the one described, full system activation is dependent on one independent fire-related event: In the event of fire, heat causes one or more automatic sprinklers at the Dry pilot line to open, leading to depressurization of the pipeline. The pressure drop opens a pneumatic actuator located on the deluge valve control chamber drain line, and consequently the deluge valve opens allowing water to flow into the sprinkler pipeline.
The resulting pressure drop triggers the air pressure switch, which sends a signal to the main control board. This is for supervision only.
