FLUID FLOW CONTROL VALVES

摘要

Wet blast apparatus 1 is provided with a sump 2 for collecting liquid and abrasive particles after use, a duct 40 for conducting the collected material to a three-stage weir system 4 whereby the particles are separated out. The apparatus is further provided with a fluid flow control valve 3 operable to control the flow of collected material to the separating system 4. An adjustable timer 25 is provided for delaying the flow of collected material to the separating system 4. The control valve 3 comprises a valve member 6 cooperable with a valve seat 7, the valve member 6 being expansible whereby it can be enlarged so as to coact with the valve seat 7. The valve member 6 is of hollow, inflatable form, comprising a flexible membrane 10, clamped between a plate 11 and a ring 12. An actuating chamber 20 is defined by the plate 11 and the membrane 10. Pressurized air is admitted to, and exhausted from, the chamber 20 by way of a control valve 21 disposed in an air line 22. The control valve 21 is electrically operated, using a timer device 25 connected to the valve 21 by an electrical signal line 26. The timer device 25 is also electrically connected to an electrically-driven pump 27, used to discharge the slurry against the workpiece (not shown) to be treated by the apparatus 1. The timer 25 is operable to delay opening of the control valve 3, in order to allow abrasive time to settle in the sump 2.