| 摘要 |
<p>A stem operated valve having a body and a bonnet secured to the body, a valve member movably positioned within the body, and a stem secured to the valve member and extending into the bonnet, a seat on the bonnet surrounding the stem, a shoulder on the stem adapted to engage the seat, a stem packing positioned outward of the stem shoulder and bonnet seat, a fusible material at the outer end of the bonnet and stem supporting the stem with its shoulder spaced from the bonnet seat during normal operations and holes in the through which the fusible material exits when the valve is exposed to fire whereby the stem shoulder engages the bonnet seat to seal around the stem.</p> |
