| 摘要 |
<p>A pressure relief valve (10) is described which includes an apertured ball valve element (28), which is spring-loaded, and which is rotatably and axially mounted in the valve bore so that when an over-pressure situation arises fluid forces the ball (28) off a ball valve seat (50) against a spring force (40) and causes the ball valve (28) to rotate such that the aperture (32) in the ball valve (28) connects the inlet bore (20) and outlet bore (22) of a valve housing (16) so that fluid can flow through the pressure relief valve (16). When pressure at the inlet falls beneath a predetermined value, the spring force (40) forces the ball (28) to rotate and move back against the valve seat (50), thus closing the valve (10). With this arrangement there is minimal pressure exerted on the valve housing (16) and the valve (10) will operate with a back-pressure up to 50 % of the inlet pressure. This means that much smaller bore outlet piping can be used with savings in weight and, consequently, cost. For example, 3 in. piping may be used instead of 8 in. or larger piping for the equivalent rated valves.</p> |
