Abstract: A sandblast apparatus includes a telescopically nested tubular abrasive induction probe operable as a vacuum conveyor for inducting an abrasive material into a discharge apparatus. The discharge apparatus is supplied with a source of water under pressure which enters the discharge apparatus as a stream and admixes with the abrasive material in a diverging chamber. The discharge device, formed of lightweight aluminum material has an air control to afford remote control of abrasive feed and to form a protective air shield for the abrasive stream. After admixture, the stream is discharged through a converging nozzle to a point of utilization.

Abstract: A metering pulse pump for metering an additive liquid into a liquid carrier under high pressure. A high-pressure, rapidly reciprocating piston pump is provided at its outlet end with a pressure-relief valve including a spring pressure control permitting the valve to open under varying pre-set pressure differentials across the valve. A diaphragm pump having first and second chambers separated by a diaphragm is provided with one of the chambers communicating directly with the outlet of the piston pump upstream of the pressure-relief valve, liquid carrier emitted under pressure from the piston pump serving to drive the diaphragm pump in a pumping stroke, the second chamber of the diaphragm pump having inflow and outflow ports with respective check valves permitting only inflow and outflow of an additive liquid into and out of the second chamber.