| 摘要 |
<p>1493763 Fire protection valve O A LARSEN 14 Jan 1976 [31 Jan 1975] 1448/76 Heading A5A [Also in Divisions F2 and F4] An adjustable ventilation and fire protection valve comprises a head 1 fitting a seat 2, a screw-threaded valve stem 4, a support bracket 3 for the stem 4 and a valve spring 6 acting on plate 7 to maintain a valve adjusting nut 5 abutting- 3, wherein the threads of nut 5 are formed from a fusible material 8 which grips the stem 4 sufficiently to cause 5 to rotate therewith when the valve head 1 is rotated and thus maintain the valve in its pre-set position, but which in fire conditions melts to release 5 and allow spring 6 to close the valve. A paste may be provided on the thread of stem 4 to increase friction between it and the nut 5.</p> |
