Valves

A self-energizing valve, comprising:

• a valve body having an inner wall defining an inner chamber in fluid communication with a valve inlet and a valve outlet;
• a valve head positioned within the inner chamber, the valve head moveable between a first position and a second position;
• a valve seal in fluid communication with the valve inlet and having a sealing surface;
• a slide seal retainer positioned within the valve body retaining a slide seal, a distal end portion of the valve head slidable through the slide seal, the slide seal preventing a flow of fluid between the slide seal and the distal end portion of the valve head;
• a valve seal retainer comprising a cylindrical body with a central bore and an outlet port in fluid communication with the valve outlet and being spaced from the valve seal to allow the valve seal to flex to engage a second seal, the second seal positioned between a distal end of the valve head and the valve seal and positioned within the central bore of the valve seal retainer, the second seal movable between a first closed position where the second seal engages with the sealing surface of the valve seal to seal the inlet and a second open position where the second seal is disengaged from the sealing surface of the valve seal and to allow flow through the inlet into the inner chamber, and wherein when an outlet fluid pressure at the outlet exceeds an input fluid pressure, the outlet fluid pressure forces the second seal into engagement with the valve seal to prevent a flow of fluid from the valve outlet to the valve inlet;
• and
• a cam engaged with a first surface of the valve head, whereby rotation of the cam causes movement of the valve head between the first position and the second position and whereby movement of the valve head to the first position holds the second seal in the first closed position and whereby movement of the valve head to the second position allows movement of the distal end of the valve head head away from the second seal by a biasing device interposed between the valve head and the inner chamber to apply a biasing force to the valve head away from the second seal, the cam providing sufficient force against the valve head when a semicircular side of the cam forces the valve head toward the second seal to overcome the biasing force of the biasing device.