Gate valve with camming wedge, pressure equalizer, and replaceable bleeder valve

摘要

A gate valve for controlling the passage of fluid between inlet and outlet openings comprises a housing (40) containing a reciprocating expandable gate element formed of a wedge (54) which is sandwiched between two spring-loaded plates (56 and 58) so that reciprocation of the wedge causes expansion of the plates for closing the valve's openings. In order to facilitate the return stroke of the wedge and to overcome the holding force of the vacuum on one of the plate, the device includes a bleeder valve element (80) which is connected to the first plate and has a seat on the second plate so that when the first plate (56) located on the higher pressure side commences its movement, it opens the bleeder valve element and equilizes the pressures on both sides of the valve. This eliminates the vacuum and thus the holding force. In the second embodiment, the valve has a time-delay mechanism which delays retraction of the plate on the low pressure side until a certain equilibrium of pressure is achieved.