Isolating valve for food processing plant - has valve seal leakage indicator with pneumatic shut=off valve actuator

摘要

The valve isolates a horizontal pipe (14) from a branch connection (15) by a disc valve seal which has an annular face groove (22) to form two concentric sealing surfaces. The void formed by the groove and the valve seat is connected to atmosphere, when the valve is closed. This connection is achieved by two passages (25,26) with a normally open pneumatically controlled valve (27) between them. When the isolating valve is open, the valve (27) is operated and isolates the leak. The valve (27) is opened when the isolating valve is closed and any leakage past the valve seat is detected.