Automatically closing butterfly valve - has hydraulically operated cylinder pressurised from fluid in pipeline

摘要: The operating arm (6) of the butterfly valve (7) is terminated in a fork (60) which has one branch (61) longer than other (62). A counterweight (80) also fitted to valve. Below valve, on outside pipe, hydraulic cylinder (2) supported between brackets (11,12). opened by upstream water pressure via connecting pipe (5) and closed return spring (4). During normal operation, force overcomes compressive allows forked catch-plate (3) move freely right keep open.