External Pilot Operated Valves

External Pilot Valves

External Pilot Operated Solenoid Valves - 4600 and APV Series With these types of valves, an independent external pilot source is used for controlling the pressure for actuation purposes. These valves are either piston or diaphragm types and may be actuated by either air or liquids. A 3-way solenoid pilot valve controls the independent external pilot media. In the case of Spartan externally piloted valves, the standard internal pilot valves are manipulated in a manner which separates the main valve into two sections. The upper section is the pilot pressure chamber and the lower section is for main media control. In the normal position, with pilot pressure, the main valve is closed preventing the flow of media. Pilot pressure is interrupted when the solenoid is energized. The plunger is pulled from its normal position to the raised position closing off the pilot inlet orifice. At the same time the pressure is released from the pilot chamber of the valve by means of an exhaust port. When the solenoid is de-energized the plunger returns to its normal position closing the exhaust port and the pilot pressure again builds in the pilot chamber creating the diaphragm closing force. Fig. 7. (Note - All Spartan externally piloted valves will fail open if for some reason the pilot supply pressure is interrupted). The normally open and closed functions of the main valve rely on the function of the pilot valve. For example, a normally closed external pilot valve requires a normally open pilot valve. Conversely, a normally open external pilot valve requires a normally closed pilot valve. 

Figure 7:—