The RCV-125 pressure-release pneumatic systems operate on the return-air principle. A handle installed at the nozzle connects pneumatically to inlet and outlet valves on the blast machine. With the safety petcock on the inlet valve closed, the operator depresses the handle which opens the inlet valve and closes the outlet to start blasting; releasing the handle reverses the process and blasting stops. This safety system stops blasting should the operator lose control of the nozzle. And when the blast session is over, the safety petcock is opened to prevent activation, even when the handle is depressed.
