| 摘要 |
<p>A safety apparatus for use in a hydrocutting or hydroblasting system which has a normally closed shutoff valve for coupling a high pressure water source to a hydrocutting or hydroblasting gun (100). The shutoff valve (216) is controlled by a solenoid valve (210) coupled between an air-to-open (ATO) input of the shutoff valve (216) and an air power source (118). A normally open inductive proximity switch (102), through a relay circuit (200), provides a control signal to the solenoid valve (210). The inductive proximity switch (102) is located near a cutting or cleaning nozzle (103) of the gun (100). When the inductive proximity switch (102) comes in close proximity of a metal object (M) to be cleaned or cut, the proximity switch (102) closes, thereby opening the solenoid valve (210) and the shutoff valve (216). When the gun (100) is removed from the physical proximity of the metal (M), the inductive proximity switch (102) opens, thereby turning off the shutoff valve (216).</p> |
