Pilot valves use the differential pressure of the medium over the valve ports to open and close. Also known as servo-assisted solenoids, these valves provide high flow rates and can operate at higher pressure and temperature ranges, with lower power consumption. A servo-assisted, diaphragm solenoid valve with pilot control employs the use of a small chamber directly above the diaphragm to assist in the operation of the valve. Process fluid is allowed to enter the chamber through a small orifice in the inlet port, and in a normally closed valve, compresses against the diaphragm and forces is against the seat to maintain the closing seal. Once current is applied to the pilot solenoid, the diaphragm is pulled upwards against the spring pressure, and the pilot fluid in the chamber is forced back through the orifice in the inlet port where it re-joins the main flow through the valve body. The main areas of application for pilot-controlled diaphragm solenoid valves are liquid or gaseous media (such as compressed air, water and hydraulic oils) within closed circuits in which little or no differential pressure is present for opening and closing. Benefits of Pilot solenoid valves

• Excellent for very large flow.
• Pressure assists valve operation.
• Needs minimum pressure differential.
• More economical for higher flow values
• Lower electrical power level.