| 摘要 |
<p>A low temperature valve mechanism has a housing (62, 64, 66) in which is mounted a valve stem (20) carrying at one end a valve member (52) which cooperates with a valve seat (60) surrounding a vent opening (56) in a cryogenic tank (14). A bias spring (102) acts between the top of the valve housing and the rod (20) and biases the valve member (52) into the closed position. The housing is mounted externally on a heat insulating outer shell (12) surrounding the tank so that the bias spring (102) is not subject to the low temperature of the tank (14). A pressure chamber (84) is formed between the rod (20) and the housing. By supplying fluid under pressure through a conduit (88) a force can be exerted on the rod (20) against the action of the spring (102) to open the valve (52, 60).</p> |
