| 摘要 |
<p>A check valve 200 has an elongate cylindrical tubular body 202 which provides mounting for a main flap valve 204. Mounted below the main valve 204 is a smaller multi-leaf flap valve 206. The smaller valve 206 is mounted on a housing 208 which is axially movable relative to the body 202. The housing 208 and valve 206 are normally biased upwardly and in this position a sleeve 214 formed on the upper end of the housing holds the main valve 204 open, and encloses the valve 204 within a valve recess 216 defined in the body 202. The sleeve 214 also extends across the main valve seat 218. Thus, during normal operation of the valve, with flow in a first direction, the sealing surfaces of the main valve 204 and the seat 218 are protected from the fluid by the sleeve 214.</p> |
