Fluid controlling valves

Claim 1

A FLUID CONTROL VALVE COMPRISING A CASING HAVING AN INLET AND AN OUTLET JOINED BY A PASSAGE, A MOVABLE MEMBER INCLUDING A PISTON BODY SLIDABLE FLUID TIGHTLY WITHIN A BORE IN THE CASING TOWARDS AND AWAY FROM THE INLET, A HEAD ON SAID PISTON BODY AT THE END NEARER THE INLET, AND A SKIRT EXTENDING BACK FROM THE HEAD, A CYLINDRICAL SURFACE IN THE VALVE CASING OVER WHICH THE SKIRT SLIDES, THEREBY TO FORM A CHAMBER BETWEEN THE PISTON BODY, THE BACK OF THE HEAD, AND THE SKIRT, THE PASSAGE JOINING THE INLET AND OUTLET PASSING OUTSIDE THE SKIRT AND CYLINDRICAL SURFACE, A FURTHER PASSAGE LEADING THROUGH THE MOVABLE MEMBER FROM THE CHAMBER AND OPENING AT ALL TIMES TO THE INLET TO THE CASING, TWO SEALING MEMBERS CARRIED RESPECTIVELY BY SAID HEAD AND SAID CASING AROUND THE INLET, ONE OF SAID SEALING MEMBERS BEING A RESILIENT CLOSURE MEMBER AND THE OTHER A SEATING, OPERATING MECHANISM ACTUATABLE FROM OUTSIDE THE CASING FOR MOVING THE MOVABLE MEMBER, MEANS LINKING THE MECHANISM AND MOVABLE MEMBER WITH SOME FREEDOM OF MOTION, SPRING MEANS ACTING BETWEEN THE MECHANISM AND MOVABLE MEMBER TO BIAS THE MOVABLE MEMBER TOWARDS THE INLET, THE MOVEMENT IMPARTED BY THE MECHANISM IN THE CLOSING DIRECTION BEING SUFFICIENT TO TAKE UP IN PART THE FREEDOM OF MOTION AGAINST THE SPRING BIAS AFTER THE SEALING MEMBERS HAVE COME INTO CONTACT, A SEAL BETWEEN SAID OPERATING MECHANISM AND SAID PISTON BODY, AND A SEAL BETWEEN SAID SKIRT AND THE PASSAGE PASSING OUTSIDE THE SKIRT, THEREBY CONFINING THE FLUID PRESSURE TO THE CHAMBER WITHOUT PREVENTING THE OPERATION OF THE MECHANISM OR THE MOVEMENT OF THE MOVABLE MEMBER, THE AREA OF THE BACK OF SAID HEAD BOUNDING THE CHAMBER BEING SO RELATED TO THE AREA WITHIN THE SEATING WITH WHICH THE CLOSURE MEMBER COOPERATES THAT WHEN THE VALVE IS CLOSED, THE CLOSING PRESSURE NOT SUBSTANTIALLY EXCEEDING THE PRESSURE OF THE FLUID TENDING TO OPEN THE VALVE AND IS MAINLY DERIVED FROM THE CONTROLLED FLUID PRESSURE ACTING IN SAID CHAMBER, WHILE WHEN THE MECHANISM IS OPERATED TO OPEN THE VALVE, AFTER THE FREEDOM OF MOTION HAS BEEN TAKEN UP THE MECHANISM POSITIVELY WITHDRAWS THE MOVABLE MEMBER.