Liquefied gas pump

Claim 1

IN APPARATUS FOR PUMPING A VOLATILE LIQUID HAVING A BOILING POINT TEMPERATURE BELOW 273* K. AT ATMOSPHERIC PRESSURE COMPRISING A RESERVOIR FOR CONTAINING A SUPPLY OF SUCH LIQUID, AN ELONGATED PUMP BODY HAVING A PUMPING CHAMBER THEREIN ADJACENT ONE END AND AN OPENING AT THE OTHER END, SAID PUMPING CHAMBER BEING POSITIONED IN SAID RESERVOIR, A RECIPROCABLE PUMPING ELEMENT EXTENDING THROUGH SAID OPENING IN THE PUMP BODY AND HAVING AN INNER PUMPING END PORTION OPERABLE IN SAID PUMPING CHAMBER, A VALVE-CONTROLLED INLET PORT ADJACENT SAID PUMPING CHAMBER, A VALVE-CONTROLLED OUTLET PASSAGE FROM THE PUMPING CHAMBER FOR LIQUID DISCHARGE, A PACKING MEANS IN SAID PUMP BODY ADJACENT ITS OPEN END FOR SEALING SAID RECIPROCABLE PUMPING ELEMENT IN SAID PUMPING BODY, AND A VALVE IN SAID INLET PORT, SAID VALVE BEING BIASED BY GRAVITY TO AN OPEN POSITION TO ALLOW VAPOR FORMED IN SAID CHAMBER TO FLOW TO SAID RESERVOIR, AND A HEAD ON SAID VALVE, SAID HEAD FORMING A SURFACE IN SAID CHAMBER AGAINST WHICH THE MOMENTUM OF LIQUID IN SAID CHAMBER REACTS TO CLOSE SAID VALVE AFTER SAID PUMPING ELEMENT EVACUATES VAPOR FROM SAID CHAMBER.