| 摘要 |
<p>Grit blasting apparatus comprising a compressor (1) for supplying compressed air which via a hose (4) with a hand-operated main supply valve (6) is supplied to a grit supply tank (5) for pressure generation within said tank (5), which is equipped with a vent valve (7), and to a mixing chamber (11) in which grit from the tank (5) is mixed with compressed air, the grit/air mixture formed being supplied via a grit blasting hose (13) with a mixture supply-interruption valve (35) to a grit blasting nozzle (14) to be operated by an operator at the work point relatively remote from the tank (5), with air fit for breathing being supplied via a separate air hose (20) with a reduction valve (22) to a grit blasting helmet (25) to be worn by the operator, and in which further a valve (27) operated by a so-called dead man's handle (26) is provided at the grit blasting nozzle (14), with which valve the feed to the grit blasting nozzle (14) is interrupted by releasing the handle (26). According to the invention, all valves in the operating circuit and in the feed to the grit blasting nozzle (14) are operable only by compressed air and against spring bias and the mixture supply-interruption vavle (35) is controlled by compressed air supplied to it via a control valve (32) operated by a control circuit including the valve (27) operable by the dead man's handle (26) and a starter valve (28) in the vicinity of the operator, the arrangement being such that mixture is supplied to the grit blasting nozzle only if first the dead man's handle is operated and maintained in the position in which it keeps the associated valve (27) in its open position and thereafter the starter valve is operated.</p> |
