| 摘要 |
<p>A visual signal of pressure between valve stem seals is given by a rising (26) ring, which moves upwardly with the upper stem (18) seal when there is pressure between the stem seals. The rising ring is held to the stem or valve body around the stem by a retaining (32) ring. The rising ring, in its up position, precludes removal of the retaining ring.</p> |
