Sensing Line (Fire Pump Controller) – Section 4.32

One End of the fire pump sensing line is connected to a pressure sensor (Pressure transducer) within the controller. The other end of the sensing line is connected to the fire pump piping between the discharge check valve and discharge control valve of the fire pump assembly. This provides the controller the ability to sense pressure change in the fire protection system when the fire pump is fully in service, but also allows testing of the pressure settings even if the pump discharge control valve is closed.

The pressure-sensing line specified in section 4.32 is intended to control the starting of the pump motor and the running cycles of the fire pump.

4.32* Pressure Actuated Controller Pressure Sensing Lines.

4.32.1 For all pump installations, including jockey pumps, each controller shall have its own individual pressure sensing line.

4.32.2 The pressure sensing line connection for each pump, including jockey pumps, shall be made between that pump’s discharge check valve and discharge isolation valve.

4.32.3* The pressure sensing line shall be brass, rigid copper pipe Types K, L, or M, or Series 300 stainless steel pipe or tube, and the fittings shall be of 1∕2 in. (15 mm) nominal size.