Abrasive blasting system

Claim 1

A DEVICE FOR FLUIDIZING AND METERING A FLOW OF FINELYDIVIDED ABRASIVE PARTICLES CONTAINED IN AN AIR STREAM COMPRISING, IN COMBINATION: A SOURCE OF AIR UNDER PRESSURE; A PRESSURE VESSEL CONTAINING A SUPPLY OF FINE ABRASIVE PARTICLES; A HOUSING SECURED TO THE BOTTOM OF SAID VESSEL; A POROUS PARTITION HAVING A LARGE NUMBER OF TORTUOUS AIR PASSAGES AND SEPARATING SAID HOUSING FROM SAID PRESSURE VESSEL WHILE FORMING A SPACE IN SAID HOUSING BELOW SAID PARTITION; A FIRST CONDUIT EXTENDING FROM SAID AIR PRESSURE SOURCE AND CONNECTED TO SAID HOUSING BELOW SAID PARTITION; A SECOND CONDUIT EXTENDING FROM SAID AIR PRESSURE SOURCE AND CONNECTED TO A BLAST NOZZLE; AN ABRASIVE FEEDING TUBE AT THE BOTTOM OF SAID PRESSURE VESSEL EXTENDING THROUGH SAID POROUS PARTITION AND SAID HOUSING, AND HAVING AN ORIFICE AT ITS UPPER END OPEN TO THE INTERIOR OF SAID PRESSURE VESSEL, SAID TUBE ALSO BEING CONNECTED AT ITS LOWER END TO SAID SECOND CONDUIT; AND PRESSURE REDUCING MEANS IN SAID SECOND CONDUIT FOR REDUCING THE AIR PRESSURE IN SAID SECOND CONDUIT AND THEREBY CONTROLLING THE METERING OF ABRASIVE PARTICLES THROUGH SAID FEEDING TUBE; WHEREBY WHEN SAID DEVICE IS STARTED UP, A FLOW OF AIR IS PROVIDED UPWARD THROUGH SAID SECOND CONDUIT AND SAID FEED TUBE DIRECTLY INTO SAID VESSEL TO RAPIDLY FLUIDIZE SAID SUPPLY OF ABRASIVE PARTICLES THEREIN, AFTER WHICH, WHEN EQUILIBRIUM PRESSURE IS REACHED WITHIN SAID PRESSURE VESSEL, THE ABRASIVE PARTICLES ARE CONTINUOUSLY FLUIDIZED BY THE FLOW OF COMPRESSED AIR THROUGH SAID FIRST CONDUIT AND SAID POROUS PARTITION AND A FLOW OF ABRASIVE-LADEN AIR IS METERED DOWNWARD THROUGH SAID FEED TUBE AND INTO THE AIR STREAM OF SAID SECOND CONDUIT EXTENDING TO SAID BLASTING DEVICE.

Claim 2

A DEVICE FOR FLUIDIZING AND METERING A FLOW OF FINELYDIVIDED ABRASIVE PARTICLES CONTAINED IN AN AIR STREAM COMPRISING, IN COMBINATION: A SOURCE OF AIR UNDER PRESSURE; A PRESSURE VESSEL CONTAINING A SUPPLY OF FINE ABRASIVE PARTICLES; A HOUSING SECURED TO THE BOTTOM OF SAID VESSEL; A POROUS PARTITION HAVING A LARGE NUMBER OF TORTUOUS AIR PASSAGES AND SEPARATING SAID HOUSING FROM SAID PRESSURE VESSEL WHILE FORMING A SPACE IN SAID HOUSING BELOW SAID PARTITION; A FIRST CONDUIT EXTENDING FROM SAID AIR PRESSURE SOURCE AND CONNECTED TO SAID HOUSING BELOW SAID PARTITION; A SECOND CONDUIT EXTENDING FROM SAID AIR PRESSURE SOURCE AND CONNECTED TO A BLAST NOZZLE; AN ABRASIVE FEEDING TUBE AT THE BOTTOM OF SAID PRESSURE VESSEL EXTENDING THROUGH SAID POROUS PARTITION AND SAID HOUSING, AND HAVING AN ORIFICE AT ITS UPPER END OPEN TO THE INTERIOR OF SAID PRESSURE VESSEL, SAID TUBE ALSO BEING CONNECTED AT ITS LOWER END TO SAID SECOND CONDUIT; AND PRESSURE REDUCING MEANS IN SAID SECOND CONDUIT FOR REDUCING THE AIR PRESSURE IN SAID SECOND CONDUIT AND THEREBY CONTROLLING THE METERING OF ABRASIVE PARTICLES THROUGH SAID FEEDING TUBE; WHEREBY WHEN SAID DEVICE IS STARTED UP, A FLOW OF AIR IS PROVIDED UPWARD THROUGH SAID SECOND CONDUIT AND SAID FEED TUBE DIRECTLY INTO SAID VESSEL TO RAPIDLY FLUIDIZE SAID SUPPLY OF ABRASIVE PARTICLES THEREIN, AFTER WHICH, WHEN EQUILIBRIUM PRESSURE IS REACHED WITHIN SAID PRESSURE VESSEL, THE ABRASIVE PARTICLES ARE CONTINUOUSLY FLUIDIZED BY THE FLOW OF COMPRESSED AIR THROUGH SAID FIRST CONDUIT AND SAID POROUS PARTITION AND A FLOW OF ABRASIVE-LADEN AIR IS METERED DOWNWARD THROUGH SAID FEED TUBE AND INTO THE AIR STREAM OF SAID SECOND CONDUIT EXTENDING TO SAID BLASTING DEVICE.