| 摘要 |
<p>A valve means controls flow from a fluid supply (2) to a pressurised seal chamber (3) at the pump outlet of a fluid storage tank (6), in order to accommodate leaks from the seal chamber (3). The valve means comprises metering valve (8) and a non-return valve (9), though which fluid flows from the supply (2) to the seal chamber (3). The metering valve (8) is operative in response to the pressure of the supply (2) and the pressure in the seal chamber (3), and closes when the pressure differential between the supply and the seal chamber exceeds a predetermined level. However, the metering valve (8) also has a bypass (10) allowing a constant restricted flow from the supply to the seal chamber through the non-return valve (9). This arrangement means that the metering valve 8 will close if there is a substantial leak from the seal chamber (3), but if the leak rights itself, the chamber (3) will be gradually re-pressurised via the bypass, enabling normal operation of the valve means to resume.</p> |
