GB1395417A - Pressure-fluid systems - Google Patents

Abstract

1395417 Valves ALUMASC Ltd 19 July 1973 [21 July 1972] 34230/72 Heading F2V A valve for automatically changing-over from an exhausted pressure gas source to a fresh source has two inlets 13 for connection to the sources and opening at passages 14 at opposite ends of a valve chamber, an outlet 21 opening into the valve chamber intermediate its ends, and a shuttle valve comprising two pistons 16 interconnected by a stem 17 and a relatively movable sleeve 18. The pressure of the source being used forces the respective piston 16 to close the passage 14 leading to the other source and one of two seats 19 on the sleeve to abut that piston to close off the respective end of the chamber from the pressure source. On exhaustion of the source the pressure of the other source moves the shuttle valve to the opposite end of the chamber to communicate that source to the outlet. Two spring-loaded indicating plungers 25 are provided in the valve body for each source, the one upstream of the passage 14 indicating the pressure at the source and the one downstream of the passage 14 indicating which source is being used. The exhausted source can be completely vented prior to replacement via passage 24 in the plunger 25 and passage 27, communication between the latter two passages being closed when the plunger abuts the plug 26 when the source is at high pressure.