Dispensing device with purging means

Claim 1

A METERING DISPENSING DEVICE FOR CONTROLLING THE DISCHARGE OF MEASURED QUANTITIES OF MATERIAL UNDER PRESSURE OF A PROPELLENT FROM A CONTAINER, THE PORTION OF THE CONTAINER ABOVE THE MATERIAL DEFINING A HEAD SPACE HAVING GAS UNDER PRESSURE THEREIN, SAID DISPENSING DEVICE COMPRISING A HOUSING DEFINING A MEASURING CHAMBER HAVING A NORMALLY OPEN INLET PORT FOR RECEIVING THE MATERIAL IN THE CONTAINER AND A NORMALLY CLOSED OUTLET PORT FOR DISPENSING THE MATERIAL FROM THE HOUSING, A RECIPROCATING VALVE STEM HAVING A DISPENSING NOZZLE ON THE OUTER END THEREOF, SAID VALVE STEM BEING NORMALLY URGED TO A PROJECTING POSITION AND HAVING MEANS FOR FIRST CLOSING THE INLET PORT AND THEREAFTER OPENING THE OUTLET PORT IN RESPONSE TO INWARD MOVEMENT OF THE STEM FROM SAID NORMAL POSITION TO DISPENSE THE MEASURED QUANTITY OF MATERIAL FROM AND CHAMBER, A PURGING PORT IN THE SIDE OF THE HOUSING COMMUNICATING SAID CHAMBER WITH THE SAID HEAD SPACE, AND MEANS CONTROLLED BY SAID VALVE STEM FOR NORMALLY SEALING SAID PURGING PORT UNTIL THE VALVE STEMS HAS BEEN MOVED INWARDLY TO A POSITION IN WHICH THE MATERIAL HAS BEEN DISPENSED FROM THE HOUSING AFTER WHICH THE PURGING PORT IS UNSEALED BY CONTINUED INWARD MOVEMENT OF THE STEM AND GAS FROM SAID HEAD SPACE FLOWS THROUGH SAID PURGING PORT, OUTLET PORT AND NOZZLE TO PURGE THE SAME OF ANY MATERIAL REMAINING THEREIN.