| 摘要 |
<p>An apparatus (100) includes a first valve (114) configured to selectively direct material to first and second outlets (118, 122) and a second valve (120) configured to block the second outlet. The first and second valves define a dead space (126) that has a volume between the first and second valves. The apparatus also includes a pressure compensation unit (128) configured to dynamically provide an additional volume for material trapped in the dead space when the trapped material expands. The pressure compensation unit could include a piston (132) configured to move within a space (130) of the pressure compensation unit, where increased pressure in the dead space causes the trapped material to push against the piston in order to provide the additional volume for the trapped material. The pressure compensation unit could further include a spring (134) configured to bias the piston and a seal (136) configured to substantially prevent the trapped material from passing the piston and contacting the spring.</p> |
