Pressure relief valve for road fuel tanker - has counterweight which actuates ball valve to prevent excessive over or under pressure within tank if vehicle overturns

摘要

The inward and outward pressure relief valve is screwed into a boss (2) welded to the wall (1) of the fuel tank. The inward relief valve consists of a spring disc (10) secured by a circlip (11) and sealing on the valve seat (8). The outward relief valve is formed by a ball (21) loaded by a spring (20) which seals the mouth of the tube, (23). A second outward relief valve to deal with an excessive pressure rise is formed by the valve seat (8) which is guided by legs (8a) and is held on the sealing washer (6) by the spring (13). A ball valve (25) shuts off access to the tube (22) by the action of the weight (35) in the event of the tanker overturning.