P74BA-1C Differential Pressure ControlSeries P74 measures the pressure difference between two sources: supply lines and return lines. A change in differential pressure will reposition the switching mechanism to cause corrective action of the supplementary control equipment. Product Specifications BRANDJohnson Controls CAPILLARY LENGTH FEET3 BELLOWS MATERIALStainless Steel SWITCH ACTIONSPST SWITCH OPENS ONDecrease in Pressure Difference PRESSURE CONNECTOR1/4 in. Flare Nut LIMITED WARRANTY YEARS1