| 摘要 |
<p>PCT No. PCT/AU89/00251 Sec. 371 Date Dec. 7, 1990 Sec. 102(e) Date Dec. 7, 1990 PCT Filed Jun. 9, 1988 PCT Pub. No. WO89/12192 PCT Pub. Date Dec. 14, 1989.A valve assembly which comprises an upper valve assembly and a lower valve assembly. The upper valve assembly includes a valve body, a spring retainer and an upper spring. The lower valve assembly includes a retainer ring, an O-ring and a valve seat member. The valve body comprises a valve disc and a valve stem. The valve disc has a lower peripheral surface which is bevelled, and the lower extremity of the bevelled surface meets an annular protrusion which has a flat lower surface. The O-ring fits within respective grooves provided in the retainer ring and the valve seat member. The valve seat is arranged to be located in a valve port, and when the upper valve assembly is moved downwardly the annular protrusion is forced against the O-ring which then forms an additional seal with the adjacent housing of the valve port to completely close the valve assembly.</p> |
