FPPI’s 1/2” IPS Brass* Check valve with 3/4 ” orifice is specifically designed for use in the pressure sensing line for fire pump systems. The 1/2” swing check with a 3/4 ” orifice will provide adequate pressure drop in the sensing line without allowing unnecessary pump starts due to major pressure fluctuations that may be indicated in the larger diameter (1/2”) line. Check with pump manufacturer for proper use.