| 摘要 |
<p>A valve for use e.g. as a pilot valve in an offshore water deluge fire fighting system has a ported cylindrical body 1 and an elastomeric sleeve 3 defining between them an annular passage 4 for flow between the various ports P1, P2 and P3. Selected ports P1 and P2 can be closed by means of captive balls 11, 12 which are cammed out by a central spool 10 to deform localised areas of the sleeve 3 into sealing contact with the housing wall 2 surrounding the port openings. In this way the moving parts of the valve are isolated from the fluid by the sleeve 3 and problems of sticking, e.g. caused by salt deposits when used with seawater, are avoided. In another embodiment, (Figures 3 and 4, not shown), a flat pad of elastomeric material is used to the same effect in a ported body defining a planar flow passage.</p> |
