| 摘要 |
<p>1504849 Valves FISHER CONTROLS CO Inc 30 April 1976 [2 May 1975] 17728/76 Heading F2V A replaceable valve seat assembly comprises a cage member 36 having a seat 40 and a valve plug 42 reciprocally but non-rotatably mounted within the cage, the plug having a stem 22 with a threaded end 64 for attachment to external actuator means 60 and the upper part of the cage being threaded for attachment to a bonnet 12 whereby screwing the cage on to the bonnet also screws the stem 22 on to the actuator 60. The actuator shown comprises a diaphragm 56 mounted between a lower casing 54 and an upper casing (not shown) carried by the bonnet 12. Preferably the cage threads 34 are of greater pitch than the stem thread 64 to compress a spring 62 to close the valve tightly, in use. Flats 52 are provided on the cage to allow fitting and replacement by a wrench. Non-rotation of the plug may be by complementary hexagonal shaped surfaces 38, 44 or by a pin sliding in a vertical slot.</p> |
