Leak testing system

Claim 1

IN A TEST SYSTEM FOR INDICATING THE RATE OF PRESSURE DECREASE WITHIN A HOLLOW OF A TEST PART, MEANS TO RECEIVE A TEST PART, A SOURCE OF TEST PRESSURE, PRIMARY CONDUIT MEANS CONNECTING SAID SOURCE WITH THE HOLLOW OF THE TEST PART TO PROVIDE COMMUNICATION THEREBETWEEN FOR TRANSMITTING TEST PRESSURE TO THE HOLLOW OF SAID PART, VALVE MEANS OPERATIVELY INTEPOSED IN SAID PRIMARY CONDUIT MEANS FOR SELECTIVELY INTERRUPTING SAID COMMUNICATION; PRIMARY PRESSURE RESPONSIVE MEANS COMPRISING A CHAMBER, A PRESSURE RESPONSIVE DIAPHRAGM OPERATIVELY MOUNTED IN SAID CHAMBER AND DIVIDING THE SAME INTO TWO COMPARTMENTS, THE FIRST COMPARTMENT CONNECTED TO THE SOURCE OF THE TEST PRESSURE AND THE SECOND COMPARTMENT CONNECTED TO THE HOLLOW OF THE TEST PART ON OPPOSITE SIDES OF SAID VALVE MEANS, RESPECTIVELY, IN ORDER TO SUBJECT SAID DIAPHRAGM WHEN SAID VALVE MEANS ARE CLOSED, TO THE DIFFERENCE OF PRESSURES IN SAID COMPARTMENTS RESULTING FROM DECREASE OF PRESSURE IN THE COMPARTMENT CONNECTED TO THE HOLLOW OF THE TEST PART DUE TO THE LOSS OF PRESSURE THEREBY, AN ELONGATED MEMBER CARRYING SAID DIAPHRAGM AND AXIALLY MOVABLE THEREBY IN RESPONSE TO SAID DIFFERENCE IN PRESSURES; AN ADJUSTABLE SPRING MEANS PROVIDED AT ONE END OF SAID ELONGATED MEMBER AND ACTING THEREON TO BRING SAID DIAPHRAGM AND SAID MEMBER TO PREDETERMINED BALANCED POSITION WHEN SAID VALVE MEANS ARE OPEN, AND WHERE THE PRESSURES IN SAID TWO COMPARTMENTS ARE EQUAL; A SOURCE OF SECONDARY PRESSURE PROVIDING SUBSTANTIALLY HIGHER PRESSURE DIFFERENTIAL THAN THAT WHICH MAY BE PRODUCED BY THE PRIMARY PRESSURE RESPONSIVE MEANS, A PRESSURE INDICATING INSTRUMENT CAPABLE OF MEASURING PRESSURE DIFFERNTIAL PRODUCED BY SAID SECONDARY PRESSURE, CONDUIT MEANS CON-