Pressure relief valve

Claim 1

A PRESSURE RELIEF VALVE FOR RELIEF OF GAS FLUID PRESSURE SLOWLY RISING TO A FIRST PREDETERMINED VALUE AND FOR RELIEF OF GAS FLUID PRESSURE RAPIDLY RISING TO A SECOND PREDETERMINED VALUE SUBSTANTIALLY LOWER THAN SAID FIRST PREDETERMINED VALUE, SAID RELIEF VALVE COMPRISING A TUBULAR VALVE BODY HAVING A SUBSTANTIALLY GREATER INTERNAL DIAMETER THAN ITS AXIAL LENGTH AND AN INLET ORIFICE OF LARGE AREA AT A FIRST END AND HAVING A LATERAL ESCAPE ORIFICE OF LARGE AREA THROUGHOUT THE MAJOR PART OF THE CIRCUMFERENCE OF SAID TUBULAR BODY INTERMEDIATE SAID FIRST END AND A SECOND END, A FIRST VALVE SEAT IN SURROUNDING RELATION TO SAID INLET ORIFICE AND LOCATED BETWEEN SAID ESCAPE ORIFICE AND THE FIRST END OF SAID TUBULAR BODY, A SECOND VALVE SEAT SURROUNDING A LARGER AREA THAN SAID FIRST VALVE SEAT AND LOCATED IN SEALED RELATION TO SIDE WALLS OF SAID TUBULAR VALVE BODY IN A POSITION BETWEEN SAID ESCAPE ORIFICE AND SAID SECOND END OF SAID VALVE BODY, A RELATIVELY LIGHT LOWINERTIA CUP-SHAPED MOVABLE VALVE MEMBER OF SHEET METAL OF UNIFORM THICKNESS HAVING A BOTTOM WALL NORMALLY RESTING UPON AND MAKING SEALING CONTACT WITH SAID FIRST VALVE SEAT AND HAVING A SIDE WALL RISING AXIALLY FROM SAID BOTTOM WALL AND HAVING AN OUTWARDLY EXTENDING MARGINAL FLANGE EXTENDING FROM SAID SIDE WALL INTO NORMALLY SEALING CONTACT WITH SAID SECOND VALVE SEAT, A RESTRICTED BLEED PORT EXTENDING THROUGH SAID BOTTOM WALL OF SAID VALVE MEMBER, SAID VALVE MEMBER WHEN IN ITS NORMAL SEALING POSITION SERVING TO SUBDIVIDE THE SPACE WITHIN SAID TUBULAR VALVE BODY INTO A FIRST PORTION COMMUNICATING FREELY WITH SAID INLET ORIFICE AND SEALED TO THE OUTSIDE ATMOSPHERE AND A SECOND PORTION CONSTITUTING A CHAMBER SEALED FROM SAID FIRST PORTION EXCEPT THROUGH SAID BLEED PORT, SO THAT DURING SLOW RISE OF FLUID PRESSURE AT SAID INLET ORIFICE, PRESSURE WITHIN SAID CHAMBER WILL RISE CORRESPONDINGLY AND WILL ACT ON SAID VALVE MEMBER AT THE DIAMETER OF SAID SECOND VALVE SEAT TO TEND TO KEEP SAID VALVE MEMBER IN CLOSED AND SEALED POSITION, A LIGHT SPRING ALSO TENDING TO HOLD SAID VALVE MEMBER IN CLOSED AND SEALED POSITION, SAID VALVE MEMBER BEING RELATIVELY THIN AND LIGHT SO AS TO HAVE RELATIVELY LOW INERTIA SO THAT A RAPID RISE IN PRESSURE AT SAID INLET ORIFICE CAN READILY MOVE SAID VALVE MEMBER AWAY FROM SAID FIRST AND SECOND VALVE SEATS TO ENABLE ESCAPE OF PRESSURE THROUGH SAID ESCAPE ORIFICE, AND MEANS FOR LOWERING PRESSURE IN SAID CHAMBER UPON SLOW RISE THEREOF TO A PREDETERMINED VALUE, TO CREATE A PRESSURE DIFFERENTIAL ON OPPOSITE SIDES OF SAID VALVE MEMBER SO THAT SUCH PRESSURE DIFFERENTIAL MAY MOVE SAID VALVE MEMBER AWAY FROM SAID FIRST AND SECOND VALVE SEATS, THE CONSTRUCTION FURTHER INCLUDING A FIRST RESILIENT GASKET AT SAID FIRST VALVE SEAT AND A SECOND RESILIENT GASKET AT SAID SECOND VALVE SEAT, AND SAID CUP-SHAPED VALVE MEMBER BEING OF SUCH SIZE THAT UPON MOVEMENT OF SAID VALVE MEMBER IN AN OPENING DIRECTION AGAINST THE FORCE OF SAID SPRING, THE SEAL BETWEEN SAID VALVE MEMBER AND SAID SECOND GASKET WILL CRACK OPEN BEFORE THE SEAL BETWEEN SAID VALVE MEMBER AND SAID FIRST GASKET OPENS, THUS ALLOWING FAST ESCAPE OF GAS PRESSURE FROM SAID SECOND PORTION OF THE SPACE WITHIN SAID VALVE BODY THROUGH A LARGE ESCAPE AREA AROUND THE CIRCUMFERENCE OF SAID SECOND VALVE SEAT, THEREBY QUICKLY LOWERING THE PRESSURE WITHIN SAID SECOND PORTION OF SAID SPACE AND ACCELERATING THE MOVEMENT OF SAID VALVE MEMBER TO FULLY OPEN POSITION.