The BERMAD Model FP 400E־5D is suitable for systems that include wet pilot lines with closed fusible plugs (thermal releases), and piping systems with a wide variety of open nozzles. The typical wet pilot line, is installed in the covered area and connected to the valve trim. Providing boosted local pressure release from its control chamber, the Model FP 400E־5D is recommended for systems with remote and/or elevated pilot line fusible plugs.

In the SET position line-pressure, which is supplied to both the main valve’s control chamber [1] and a Hydraulic Relay Valve (HRV-2) [2] by the priming line [3], through a Check Valve [4], an Accelerator [5] with priming restriction and the wet pilot line [6] restriction [7], is trapped by the Check Valve, by the closed HRV-2, by the closed wet pilot line and by a closed Manual Emergency Release [8]. The trapped pressure holds the main valve’s diaphragm and plug against the valve seat [9], sealing it drip-tight and keeping the system piping dry. The HRV-2 is held closed by the pressure in the wet pilot line. Under FIRE or TEST conditions, a pilot line hydraulic pressure drop opens the HRV-2 causing water to exit through the Accelerator faster than it can be supplied. Pressure is then released from the main valve’s control chamber through the opened HRV-2, or the Manual Emergency Release, allowing the main valve to fully open and water to flow into the system piping and to the alarm device (if mounted).