Differential control valve

A differential control valve comprising:

• a housing having an interior surface defining an internal chamber with a central axis;
• a first valve seat disposed along the interior surface of the housing circumscribed about the central axis;
• a second valve seat disposed along the interior surface disposed and circumscribed about the first valve seat;
• a seal member defining a sealed position engaged with the first valve seat and the second valve seat under a sealing pressure of a fluid in the internal chamber, the seal member further defining an open position with the distal surface axially spaced from the first and second valve seats upon release of the sealing pressure of the fluid from the internal chamber, the seal member being substantially aligned with the central axis of the housing in each of the sealed and open positions;
• a first port proximate the first valve seat in communication with the internal chamber, and a second port in communication with the internal chamber, the second port being isolated from the first port when the seal member is in the sealed position and in fluid communication with the first port when the seal member is in the open position;
• at least one spring member disposed in the internal chamber of the housing and engaged with the seal member to bias and support the seal member in the open position upon release of the sealing pressure of the fluid from the internal chamber;
• and
• a plunger member having a knob to locate the seal member from the open position to a seated position against the first and second valve seats.