The shortcomings of the ball valve
1.Because the the most important valve seat sealing material of ball valve is PTFE, it is almost inert to all of the chemicals, and has a small coefficient of friction, stable performance, not aging, the temperature range and sealing performance Excellent comprehensive features. However, the physical properties of PTFE, including a higher coefficient of expansion, sensitivity to cold flow and poor thermal conductivity, require the design of the valve seat seal must be around these characteristics. Therefore, when the sealing material becomes hard, the reliability of the sealing is deteriorated. Moreover, the low-temperature grade of PTFE, can only be used in less than 180 ℃ case. Over this temperature, the sealing material will age. In the case of long-term use, it is generally used only at 120 ° C.
2. Its regulating performance relative to the cut-off valve to be worse, especially the pneumatic valve (or electric valve).