Positive displacement pump

Claim 1

IN A RECIPROCATING PISTON PUMP ADAPTED FOR PUMPING LIQUIDS, GASES AND VAPORS AT A SUBSTANTIALLY CONSTANT RATE, WHICH PUMP IS PROVIDED WITH VALVE MEANS FOR CONTROLLING THE FLOW OF FLUID TO AND FROM THE BORE OF A CYLINDER OF SAID PUMP, APPARATUS WHICH COMPRISES: A VALVE HEAD MEMBER POSITIONED TO ENCLOSE THE FLUID END OF SAID CYLINDER; PLUNGER MEANS MOVABLY POSITIONED WITHIN SAID VALVE HEAD MEMBER AND AT THE OUTER END OF THE CYLINDER BORE, SAID PLUNGER MEANS BEING PROVIDED WITH AN INTAKE PORT COMMUNICATING WITH SAID CYLINDER BORE, AND FURTHER BEING PROVIDED WITH A SURFACE COVERING THE AREA OF THE CYLINDER BORE WHICH SURFACE INCLUDES A FIRST OUTER SEATING SURFACE ADAPTED TO ENGAGE IN SEALING CONTACT WITH THE OUTER END OF THE CYLINDER, AND A SECOND INNER SEATING SURFACE LOCATED WITHIN THE PERIPHERY OF SAID OUTER SURFACE ENCIRCLING SAID INTAKE PORT AND ADAPTED TO ENGAGE IN SEALING CONTACT WITH THE END OF THE PISTON; CHECK VALVE MEANS IN FLOW COMMUNICATION WITH SAID INTAKE PORT, SAID CHECK VALVE MEANS COMPRISING A VALVE HOUSING PROVIDED WITH INLET AND OUTLET PORTS COMMUNICATING TO PERMIT A FLOW OF FLUID INTO AND OUT OF SAID HOUSING, A MAGNET RIGIDLY MOUNTED IN SAID HOUSING, A VALVE SEAT ENCOMPASSING SAID OUTLET PORT AND A MAGNETICALLY RESPONSIVE VALVE DISC MOVABLY POSITIONED IN SAID HOUSING BETWEEN SAID CHECK VALVE PORTS, WHICH VALVE DISC IS ATTRACTED TO SAID MAGNET AND ENGAGES WITH SAID SEAT TO CLOSE SAID OUTLET PORT DURING THE DISCHARGE STROKE OF SAID PISTON AND DISENGAGES FROM SAID SEAT UNDER INLET FLUID PRESSURE INFLUENCE GREATER THAN THE ATTRACTION OF SAID MAGNET TO OPEN SAID OUTLET PORT DURING THE INTAKE STROKE OF SAID PISTON, MEANS ADAPTED FOR MAINTAINING SAID PLUNGER MEANS IN SEALING CONTACT WITH SAID CYLINDER BORE DURING THE INTAKE STROKE OF SAID PISTON AND RESPONSIVE TO PRESSURE IN SAID CYLINDER BORE TO PERMIT MOVEMENT OF SAID PLUNGER MEANS AWAY FROM THE END OF SAID CYLINDER BORE AT A PRESELECTED PRESSURE, CONDUIT MEANS FOR PASSING FLUID TO BE PUMPED TO SAID CHECK VALVE INLET PORT, AND FLUID DISCHARGE CONDUIT MEANS COMMUNICATING WITH SAID CYLINDER BORE WHEN SAID FIRST OUTER SEATING SURFACE OF SAID PLUNGER MEANS IS DISENGAGED FROM SAID OUTER END OF SAID CYLINDER DURING THE DISCHARGE STROKE OF SAID PISTON.