| 摘要 |
Testing of a safety valve is described where the valve comprises a valve stem biased relative to a valve body. A first test apparatus is described comprising a rotor mounted helically on said valve stem and a driver adapted to rotate the rotor. Rotation of the rotor causes an axial force between the valve stem and the rotor and allows the rotor to be moved into and out of engagement with the valve stem. When engaged the rotor can apply a pre-load to the stem, and may provide sufficient force to achieve valve lift. Alternatively a two stage actuator system may be employed, the first stage / actuator providing engagement between a second stage / actuator and the valve stem, the second stage / actuator providing lift after application of the pre-load by the first stage. Sensors may measure the load, displacement of the valve stem.
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