| 摘要 |
<p>A pressure (1) release valve is disclosed ideally for use on petrol tankers which can rollover in an accident. There is a requirement for such valves both to become sealed in the event of a rollover to prevent the escape of volatile and flammable fluid from within the tanker, and also to allow for the venting of gas above the fluid within the tanker under normal operating conditions. The valve comprises a movable plunger (24) and a fixed seat (32) which can move axially towards and away from each other to open and close the valve. One or other of valve seat and plunger is provided with magnetic inserts (23), while the alternate component is ferromagnetic so that magnetic attraction betwixt the two components acts to bias the valve towards a closed condition. Once the pressure differential across the valve attains a predetermined and variable level (if the displacement of the magnets can be varied within the said component, the magnetic attraction can be varied), then the plunger is separated from the valve seat, the valve is opened, and pressure can be released therethrough. The valve is also optionally provided with a manual pressure release means (27) which is actuable even in the event of a rollover to allow for safe draining of the fluid from within the tanker.</p> |
