Liquid sample pump assembly

Claim 1

IN A PUMP FOR TAKING SAMPLES OF LIQUID FROM A LIQUID CONTAINER THE IMPROVEMENT COMPRISING, A BODY HAVING A BORE EXTENDING THERETHROUGH, A STUFFING BOX AT EACH END OF THE BORE, A PISTON ROD LOOSELY RECEIVED IN THE BORE AND SEALINGLY AND SLIDABLY EXTENDING THROUGH EACH STUFFING BOX, A HOLLOW PISTON ON THE PISTON ROD WITHIN THE BORE AND SLIDABLE WITH RESPECT TO A LIMITED PORTION OF THE PISTON ROD, SAID PISTON HAVING AN EXTERNAL PORTION SNUGLY AND SLIDABLY FITTING THE BORE, AND AN INTERNAL DIAMETER GREATER THAN THE EXTERNAL DIAMETER OF SAID PORTION OF THE PISTON ROD, MATING VALVE SURFACES ON THE LIMITED PORTION OF THE PISTON ROD AND THE PISTON ADAPTED TO SEALINGLY ENGAGE EACH OTHER UPON MOVEMENT OF THE PISTON ROD IN A FIRST DIRECTION AND TO SEPARATE UPON MOVEMENT OF THE PISTON ROD IN A SECOND DIRECTION, A PASSAGEWAY FOR LIQUID COMMUNICATING BETWEEN THE BORE AND A POINT ON SAID LIMITED PORTION OF THE PISTON ROD SPACED FROM THE VALVE SURFACES, A LIQUID INLET LINE TO AND A LIQUID OUTLET LINE FROM THE BORE AT AXIALLY SPACED POINTS ALONG THE BORE, AND A RELIEF VALVE IN THE LIQUID OUTLET LINE, SAID RELIEF VALVE HAVING A FLOW PASSAGEWAY COMMUNICATING BETWEEN THE LIQUID OUTLET LINE AND THE EXTERIOR OF THE RELIEF VALVE, A MOVABLE VALVE MEMBER IN THE RELIEF VALVE ADAPTED UPON ALTERNATE MOVEMENT TO