System protection valve.

摘要

A protection valve for fluid operatet systems, having two or more valve elements each of which opens against a bias to admit fluid under pressure to an associated fluid operated system and comprising a plunger (40) biased toward a position wherein it closes off an outlet port for connection to the associated system and carrying a non-return valve (44) which is movable to the plunger (40) such that communication between a bleed-hole (52) through the non-return valve (44) and the outlet port associated with the valve element is cut off below the closing pressure of the valve element. Because the bleed by-pass (52) is only active between valve opening and closing pressures, all sound systems can be protected against failure in any other system below valve closing pressure.