Common ball valve structure: the ball valve that is used as the opening and closing valve ball. The main function of the ball valve is to cut off or connect the fluid passage in the pipe. The principle of action is very simple: a certain torque is applied to the upper end of the valve rod by means of a handle or other driving device and the ball valve is rotated by 90 DEG C to make the ball passage and Valve body center line of coincidence or vertical channel to complete the valve fully open or closed. Ball valve is mainly composed of the valve body, seat, ball, stem, handle (or other drive). It is evolved by the plug valve, and its opening and closing pieces is a sphere, the use of the ball around the axis of the stem rotated 90 ° to achieve the purpose of opening and closing. The ball valve is mainly used to cut off, distribute and change the medium flow direction in the pipeline. The ball valve designed with V-shaped opening also has good flow regulation function. Common ball valve advantages: ①has the lowest flow resistance (actual 0); ② because of work will not get stuck (in the absence of lubricant), it can be reliably used in corrosive media and low boiling point liquid; ③ In the larger pressure and temperature range, can achieve a complete seal; ④ can achieve fast opening and closing, opening and closing time of some structures only 0.05 ~ 0.1s, to ensure that the test bed can be used in automation systems. Quick opening and closing the valve, the operation without impact. ⑤ spherical closure can be automatically positioned in the border position; ⑥ working medium sealed on both sides of reliable; ⑦ in the fully open and fully closed, the sealing surface of the ball and the valve seat and media isolation, so the high-speed valve through the media will not Resulting in erosion of the sealing surface; ⑧ compact structure, light weight, it can be considered for low temperature medium system is the most reasonable valve structure; ⑨ valve body symmetry, especially welded body structure, can well withstand the stress from the pipe ; ⑩ closing pieces can withstand the high pressure drop off. ⑾ fully welded ball valve body, can be buried directly in the ground, so that the valve parts from erosion, the highest life of up to 30 years, is the ideal oil and gas pipelines valves. Common ball valve shortcomings: ①because the ball valve seat ring is the most important material PTFE, which is almost all of the chemicals are inert, and has a small friction coefficient, stable performance, easy to aging, temperature range Wide and sealing performance of the comprehensive characteristics. However, the physical properties of polytetrafluoroethylene, including its high coefficient of expansion, sensitivity to cold flow and poor thermal conductivity, require that seat seal design be centered around these characteristics. Therefore, when the sealing material is hardened, the reliability of the sealing is destroyed. Moreover, the low temperature grade of PTFE, can only be used in less than 180 ℃. Above this temperature, the sealing material will age. Considering the long-term use of the case, generally only 120 ℃ do not use. ② its regulating performance relative to the cut-off valve to be worse, especially pneumatic valve (or electric valve).
Moving Beam Light,Sharpy Beam Light,Mini Sharpy Light,Sharpy Beam Moving Head Light,Led Sharpy Light
Big Dipper Laser Science And Technology Co., Ltd , https://www.bigdipper-laser.com