| 摘要 |
The arrangement employs a diaphragm 10 located between two chambers A, B, to which different pressures are applied to cause the diaphragm to move to open and close a ball valve 12. The diaphragm 10 and ball valve 12 are joined by a rod or stem 11 in contact with the diaphragm but not joined to it. If the pressure differential across the diaphragm becomes too great, the stem and diaphragm may separate thus causing unbalance because of the pressure applied to the end of the stem which is normally in contact with the diaphragm. To balance the valve in this condition, a check valve Y is provided which opens when the pressure in chamber A below diaphragm 10 reaches a predetermined high level. This high pressure is then applied via passage 17 to the underside of ball 12 thus balancing the pressure applied to the upper end of valve stem 11. <IMAGE> |
