Series SSPV20DP is a remote sensed, diaphragm actuated Pilot that is used for maintaining a constant differential. It is normally held closed by the force of the adjustable spring and low (downstream) pressure above the diaphragm. The high(upstream) pressure is pushing the pilot open. The pilot modulates toward an open position as the differential pressure increases, in turn relieving the main valve cover pressure and modulating the main valve open to maintain the differential set pressure. As the differential pressure decreases, the pilot modulates toward a closed position, building pressure in the main valve cover and closing the main valve. The SSPV20DP senses high control pressure through a tapped port below the diaphragm and the low pressure through a taped port in the spring cage. The large diaphragm-to-seat ratio allows it to open and close within close pressure tolerances, accurately positioning the Main Valve. Turning the adjustment screw clockwise raises the differential setpoint. Turning the adjustment screw counterclockwise lowers the differential setpoint. The SSPV20DP is equipped with one 1/2 in NPT inlet and outlet port, a 1/4 in NPT side sensing port located on the power chamber and a 1/4 in NPT sensing port located in the cover. The 1/4 in port in the power chamber is for sensing high (upstream) pressure and the 1/4 in port in the cover is for sensing low (downstream) pressure.