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| 单密封结构阀座嵌入支承圈后靠弹簧的预紧力和活塞效应使阀座与球体压紧而密封，当阀体中腔由于某种原因而出现 异常升压，阀座在压差作用下自动泄压，防止危险的发生。泄压后阀座自动复位(图9)|
For the seatring of the single-seal structure，it depends on，afte r being inlaid into the support ring，the spring’s pre-tightening force and the piston effect to have both seat ring and ball pressed tightly so as to form sealing When an abno rmal pressure riseoccurs inside of the middle cavity of the body due to some reason，the seat ring willautomatically discharge the pressure under the action of pressure differential to prevent any danger from happening，then after discharging the pressure it is reset automatically(Fig.9)
双密封结构阀座支承和0形圈支承构成的双密封结构，弹簧预紧力使阀座与球体接触，同时在管线上游侧(下游侧)和阀 体中腔压差作用下密封，无论哪边的介质压力高，在弹簧的预紧力和活塞效应使上下游侧的阀座总是和球体紧密接触 而完全阻塞流体，即使任何一方阀座损伤也能防止泄漏，但没有自动泄压作用，必须在阀体中腔装泄压装置，防止阀 体中腔的异常升压。
For the dual-seal structure fo rmed with the supports of both dual-seal structured seat ring and O-ring both seat ring and ball are made contacted under the spring’spre-tightening force and sealed under the pressure differential on the upstream(downstream)side of the pipeline and the middle cavity of the body Regardless of on which side the medium’s pressure is higher both spring’spre-tightening force and piston effect make the seatrings on both upstream and downst ream sides always tightly contacted with the ball to completely cut off the fluid and prevent leak even if any one of them gets damaged However the re is no automatic pressure discharge function，so a pressu re discharger has to be mounted in the middle cavity of the body to avoid abnormall pressure rise the rein.
Fullor reduced diameter
The valve flow aperture is identical to the inner diameter of the Pipelire(which can be reduced one if so required by usersl for the sake of cleaning(Fig.17)
Use a locker to fix the valve so as to Prevent malope ration of it and keep it in the correct opened or closed position
Extension of stem
Extension of the stem is suitable for use under-ground and at low temperature the extended size is depended on the necessity and the operation mode can be manual，pneumatic，electric，gas- hydraulic jointed or hydraulic actuation，also upon the necessity.
Reliabi|ify of ope ration
The relative sliding portion(seat ring and stem bearing)of a large aperture ball valve has a small operational to rquedue to its use of teflon which has a small friction coefficient and can be flexibly operated for a long time even if there is no lubrication supplied for it.
Different actijation modes
The used,different and effective actuation modes include manual，pneumatic，elect ric，hydraulic and gas-hydraulic jointed ones