| 摘要 |
A pressure relief valve (1,fig.1) features a piston 4 between an inlet 2 and outlet 6, and a chamber 3, with a bleed line either in the piston (30,fig.1) or an external housing 40, which puts the inlet 2 and the chamber 3 in fluid communication with each other. In this manner variations in internal pressure will not cause the valve (1,fig.1) to vent, as the chamber 3, equalises the pressure on the top side of the piston 4, to that on the bottom side of the piston 4. Under conditions of substantial internal overpressure, the piston 4 moves into the chamber 3, as can be seen in the transition from fig.2 to fig.3, fluid in the chamber 3 escaping via the bleed line 40 and/or around the sides of the piston 4. The valve (1,fig.1) may accommodate the pressure differentials of the device travelling at alternate altitudes, for example by lorry or by plane, without venting, whilst still permitting venting under conditions of substantially increased internal pressure. |
