Liquid purging systems

Claim 1

A LIQUID DISCHARGING SYSTEM COMPRISING A PRESSURE GAS SUPPLY, A CONDUIT BETWEEN SAID PRESSURE GAS SUPPLY AND A DRAIN DEVICE, A RESTRICTING DEVICE IN SAID CONDUIT BETWEEN SAID PRESSURE GAS SUPPLY AND SAID DRAIN DEVICE, SAID DRAIN DEVICE COMPRISING A STRUCTURE HAVING A PLURALITY OF CHAMBERS, A FIRST OF SAID CHAMBERS BEING IN DIRECT COMMUNICATION WITH SAID CONDUIT, AN OUTLET CONDUIT IN COMMUNICATION WITH SAID FIRST CHAMBER, A MEMBER IN SAID DRAIN DEVICE RESPONSIVE TO PRESSURE DIFFERENTIAL BETWEEN SAID FIRST CHAMBER AND A SECOND CHAMBER OF SAID PLURALITY OF CHAMBERS, A VALVE CONNECTED TO SAID PRESSURE RESPONSIVE MEMBER TO OPEN AND CLOSE COMMUNICATION BETWEEN SAID SECOND CHAMBER AND THE ATMOSPHERE, MEANS FOR EFFECTING FLUID FLOW FROM THE FIRST CHAMBER TO THE SECOND CHAMBER WHEN THE PRESSURE IN THE FIRST CHAMBER IS GREATER THAN THAT IN THE SECOND CHAMBER AND FOR PREVENTING FLOW FROM THE SECOND CHAMBER TO THE FIRST CHAMBER WHEN THE PRESSURE IN THE SECOND CHAMBER IS GREATER THAN IN SAID FIRST CHAMBER, SAID RESTRICTING DEVICE COMPRISING A RESTRICTIVE VALVE, SAID RESTRICTIVE VALUE INCLUDING AN INTERNAL CAVITY SEPARATED BY A DILATABLE BARRIER BETWEEN INLET AND OUTLET COMMUNICATION AT SPACED POINTS THEREOF CONNECTED RESPECTIVELY TO SAID SUPPLY AND TO SAID FIRST CHAMBER, WHEREBY SAID BARRIER IS DILATED WHEN THE PRESSURE AT THE INLET CONNECTION EXCEEDS THAT AT THE OUTLET CONNECTION BY A PREDETERMINED VALUE.