Pressure actuated switch

Claim 1

A PRESSURE SWITCH HAVING A TUBULAR BASE, A FLEXIBLE DIAPHRAGM MEMBER AFFIXED TO SAID BASE TO SEAL THE TUBULAR OPENING THEREOF, A SWITCH ACTUATOR ROD MOVABLY POSITIONED IN RELATION TO SAID BASE HAVING ONE END THEREOF IN ENGAGEMENT WITH SAID DIAPHRAGM, A COIL SPRING TO APPLY PREDETERMINED PRESSURE AGAINST SAID DIAPHRAGM, A SWITCH BASE ADJUSTABLY LOCKABLE TO SAID TUBULAR BASE, MEANS LOCKABLE TO SAID SWITCH BASE TO ADJUST SAID SPRING PRESSURE, SAID SWITCH BASE HAVING AN OPENING THEREIN ADAPTABLE TO SLIDEABLY RECEIVE SAID SWITCH ACTUATOR ROD, AND A SWITCH AFFIXED TO SAID BASE HAVING A SWITCH ACTUATOR ELEMENT CONTACTABLE WITH SAID SWITCH ACTUATOR ROD; A PISTON SLIDEABLY POSITIONED IN THE TUBULAR OPENING OF SAID BASE, SAID PISTON ENGAGEABLE AGAINST THAT SIDE OF SAID DIAPHRAGM OPPOSITE THAT SIDE ENGAGED BY SAID SWITCH ACTUATOR ROD, SAID PISTON HAVING AN ANNULAR GROOVE FORMED THEREIN TO RECEIVE A GASKET MEMBER, SAID GROOVE DEFINED IN PART BY A FORWARD SIDE SLOPED IN A DIRECTION OPPOSITE THE DIRECTION FROM WHICH PRESSURE IS APPLIED TO SAID PISTON, SAID GASKET BEING A DEFORMABLE O-RING POSITIONED IN SAID GROOVE TO CONTACT SAID TUBULAR OPENING OF SAID BASE WHEREBY SAID ORING UNDER PRESSURE IS DISPOSED TO DEFORM PRIMARILY TOWARD THE INTERIOR OF SAID GROOVE WHEREBY THE AREA OF CONTACT BETWEEN SAID O-RING AND SAID TUBULAR OPENING IS NOT MATERIALLY INCREASED BY INCREASE OF PRESSURE WITHIN SAID TUBULAR OPENING, YET PROVIDES A SEAL BETWEEN SAID DIAPHRAGM AND SAID PRESSURE.