Spray gun and nozzle

Claim 1

A VARIABLE, CONTROLLED VOLUME DISPENSING GUN FOR ABRASIVE, FLOWABLE MATERIALS COMPRISING: HOUSING MEANS CONTAINING CYLINDRICAL CHAMBER MEANS AND HAVING A CAP PORTION ON ONE END; A RECIPROCABLE ACTUATING PISTON IN SAID CHAMBER MEANS AND SEALINGLY ENGAGED WITH THE PERIPHERAL WALL OF SAID CYLINDRICAL CHAMBER MEANS; PRESSURIZED-FLUID PASSAGEWAY MEANS COMMUNICABLE WITH SAID CHAMBER MEANS ON ONE SIDE OF SAID PISTON; ABRASIVE MATERIAL INLET MEANS COMMUNICATING WITH SAID CHAMBER MEANS ON THE OPPOSITE SIDE OF SAID PISTON; A DIAPHRAGM IN SAID CHAMBER MEANS SEALINGLY ENGAGED ACROSS SAID CHAMBER ADJACENT ONE END THEREOF ISOLATING SAID INLET AND OUTLET MEANS FROM CONTACT WITH SAID PISTON; SAID DIAPHRAGM ADAPTED TO FLEX TOWARD SAID PISTON UNDER THE INFLUENCE OF LIQUID THROUGH SAID LIQUID INLET MEANS, AND TO BE REVERSELY FLEXED BY SAID PISTON UNDER THE INFLUENCE OF PRESSURIZED FLUID; ONE SIDE OF SAID PISTON HAVING AN EXTENSION ENGAGING SAID DIAPHRAGM TO SHIFT SAID DIAPHRAGM UPON BEING ACTUATED BY FLUID PRESSURE ON SAID ONE SIDE OF SAID PISTON; A THREADED ADJUSTMENT VOLUME CONTROL STUD HAVING AN ADJUSTING HEAD OUTSIDE SAID CAP PORTION, AND EXTENDING THROUGH AND THREADABLY ENGAGED WITH SAID CAP PORTION AND EXTENDING AXIALLY INTO SAID CYLINDRICAL CHAMBER; THE SAID ONE SIDE OF SAID PISTON ENGAGING SAID STUD IN ONE EXTREMITY OF MOVEMENT OF SAID PISTON WHEREBY THE MOVEMENT OF SAID PISTON IS REGULATED BY ADJUSTMENT OF SAID STUD TO REGULATE THE MOVEMENT OF SAID DIAPHRAGM AND THUS THE VOLUME OF ABRASIVE MATERIAL FROM SAID GUN; A CHECK VALVE ASSOCIATED WITH SAID INLET MEANS TO ALLOW ONLY INWARD FLOW; A BIASED CHECK VALVE ASSOCIATED WITH SAID OUTLET MEANS TO ALLOW ONLY OUTWARD FLOW WHEN SAID DIAPHRAGM MEANS IS FLEXED BY SAID PISTON; AND SAID BIASED CHECK VALVE MEANS BEING OPERABLE ONLY BY A PRESSURE GREATER THAN THE PRESSURE REQUIRED TO OPEN SAID INLET CHECK VALVE MEANS, WHEREBY ABRASIVE MATERIAL UNDER PRESSURE CAN BE FORCED INTO SAID INLET MEANS TO SHIFT SAID DIAPHRAGM AND THUS SAID PISTON UNTIL SAID PISTON ENGAGES SAID ADJUSTABLE STUD, SO THAT PRESSURIZED FLUID THROUGH SAID PASSAGEWAY AND ON ONE SIDE OF SAID PISTON CAN SHIFT SAID PISTON AND SAID DIAPHRAGM IN THE OPPOSITE DIRECTION TO DISPENSE A CONTROLLED VOLUME OF ABRASIVE MATERIAL.