A vent valve comprises a valve housing defining a vent port and a valve member mounted within the housing so as to define a fluid system chamber and an activation chamber with the housing. The valve member is biased towards a closed position, in which fluid communication between the fluid system chamber and the vent port is prevented, by fluid pressure within the fluid system chamber acting on the valve member. The valve member is biased towards an open position, in which there is fluid communication between the fluid system chamber and the vent port, by fluid pressure within the activation chamber acting on the valve member. The vent valve further comprises a pressure limiting arrangement associated with the activation chamber to limit pressure therein to a predetermined pressure value.
展开▼
