Piston seal for a multistage high pressure gas compressor

Claim 1

A MULTISTAGE COMPRESSOR COMPRISING A HIGH PRESSURE PUMPING CHAMBER WITH A RECIPROCABLE AXIALLY THEREIN, PISTON SEAL RINGS SLIDABLY CONTACTING THE WALL OF SAID CHAMBER, A NEXT LOWER PRESSURE PUMPING CHAMBER WITH A PISTON RECIPROCABLE AXIALLY THEREIN, VALVED GAS INLET MEANS AND VALVED GAS OUTLET MEANS ON EACH OF SAID PUMPING CHAMBERS, A POWER MEANS MECHANICALLY COUPLED TO AND RECIPROCABLY DRIVING SAID PISTONS IN OPPOSITE PHASE IN THE RESPECTIVE PUMPING CHAMBERS, A PACKING CHAMBER AT AN AXIAL END OF SAID HIGH PRESSURE PUMPING CHAMBER, THE PISTON OF SAID HIGH PRESSURE PUMPING CHAMBER EXTENDING AXIALLY THROUGH SAID PACKING CHAMBER, A PLURALITY OF U-RING PACKINGS FIXEDLY MOUNTED IN AXIALLY SPACED RELATIONSHIP IN SAID PACKING CHAMBER, THE RADIALLY INNER SIDES OF SAID U-RING PACKINGS BEING IN SEALING CONTACT WITH THE LAST-MENTIONED PISTON, TYPE MEANS CONNECTING SAID GAS OUTLET MEANS OF SAID NEXT LOWER PRESSURE PUMPING CHAMBER WITH SAID GAS INLET MEANS OF SAID HIGH PRESSURE PUMPING CHAMBER, ADDITIONAL PIPE MEANS CONNECTING SAID FIRSTMENTIONED PIPE MEANS AND THE SPACE AXIALLY BETWEEN SAID PISTON SEAL RINGS AND THE U-RING PACKING AXIALLY CLOSEST TO SAID HIGH PRESSURE PUMPING CHAMBER, AND A NONRETURN VALVE IN SAID ADDITIONAL PIPE MEANS.