Pressure-responsive devices

Claim 1

A PRESSURE-RESPONSIVE DEVICE COMPRISING A HOUSING FORMING A CHAMBER, A FLEXIBLE DIAPHRAGM MEANS MOUNTED IN THE HOUSING SO AS TO DIVIDE THE CHAMBER INTO TWO COMPARTMENTS AND CAPABLE OF FLEXING MOVEMENT AWAY FROM AND TOWARDS A FIRST POSITION; A STOP FOR THE DIAPHRAGM MEANS ON THE HOUSING AGAINST WHICH THE DIAPHURAGM RESTS IN THE NORMAL FIRST POSITION; FIRST BIAS MEANS BIASED BETWEEN THE HOUSING AND THE DIAPHRAGM, URGING THE DIAPHRAGM IN A FIRST DIRECTION; FLUID DUCT MEANS COMMUNICATING WITH A SOURCE OF FLUID UNDER PRESSURE AND WITH ONE COMPARTMENT ON ONE SIDE OF THE DIAPHRAGM MEANS TO URGE THE DIAPHRAGM IN A SECOND DIRECTION OPPOSITE TO THE FIRST; SECOND BIAS MEANS BIASED BETWEEN THE HOUSING AND THE DIAPHRAGM URGING THE DIAPHRAGM MEANS IN THE SECOND DIRECTION; THE TWO BIAS MEANS BEING SELECTED TO EXERT A NET DIFFERENTIAL FORCE OPPOSING MOVEMENT OF THE DIAPHRAGM IN THE DIRECTION AWAY FROM THW STOP APPROXIMATELY EQUAL TO THE FORCE OF A PREDETERMINED PRESSURE DIFFERENTIAL ACROSS THE DIAPHRAGM MEANS TENDING TO MOVE THE DIAPHRAGM MEANS AWAY FROM THE FIRST POSITION, AND THEREBY NORMALLY RETAINING THE DIAPHRAGM MEANS AGAINST THE STOP IN THE FIRST POSITION; AND INDICATING MEANS CONNECTED TO THE DIAPHRAGM AND ACTUATED BY MOVEMENT OF THE DIAPHRAGM MEANS IN RESPONSE TO A PRESSURE DIFFERENTIAL IN EXCESS OF SAID PREDETERMINED PRESSURE DIFFERENTIAL.