| 摘要 |
<p>A casing fill circulator assembly is disclosed. The fill valve (42) is constructed so that the valve member (52) moves out of the main flowpath (12) when the valve (42) is in the open position. The valve (42) is constructed so that flow opens it and the majority of the pressure drop is taken in an area other than the interface between the valve member (52) and the seat (60). For circulation, the apparatus is advanced further into the casing (14) until a cup seal (20) closes off the top of the casing (14). Once flow is initiated in that condition, internal pressure in the casing (14), at very low applied pressures, opens a circulation valve (70) and closes the fill valve (42) so that circulation through the casing (14) is accomplished through the circulation valve (70) while bypassing the fill valve (42). Erosive effects from flow on the fill valve (42) are thus eliminated during circulation. An alternative dual-function valve in the circulator/filling apparatus is disclosed where a control system senses applied pressure in the apparatus and opens the fill valve. If the apparatus has been inserted into the casing such that the top of the casing is closed with the cup seal, the same valve is then used to circulate.</p> |
