Pneumatic cut-off ball valve is an important component in the pipeline system, which is used to connect or cut off the flow medium in the pipeline, or to control the flow and pressure of the medium, or to ensure the safety of equipment and pipelines.

在發電廠熱力系統管路中，閥門是必不可少的部件。一個發電廠要使用幾千只各種各樣的閥門，這些閥門不僅控制機組的熱力過程，而且關系著機組的經濟運行和安全。所以，它們也是機組必不可少的組成部分。如給水調節閥門是用來調節鍋爐給水流 量的閥門，汽輪機調節閥門控制著進人汽輪機的蒸汽流量，從而控制機組負荷。主蒸汽管道上的閥門是用來切斷或接通鍋爐至汽輪機蒸汽的截門。汽包和過熱器的安全門是保障鍋爐安全運行的 閥門等等。

Valves are essential components in the thermal system pipelines of power plants. A power plant requires the use of thousands of various valves, which not only control the thermal process of the unit, but also affect the economic operation and safety of the unit. So, they are also an essential component of the unit. For example, the feedwater control valve is a valve used to regulate the boiler feedwater flow, while the turbine control valve controls the steam flow into the turbine, thereby controlling the unit load. The valve on the main steam pipeline is used to cut off or connect the shut-off valve from the boiler to the steam turbine. The safety valves of the steam drum and superheater are valves that ensure the safe operation of the boiler.

隨著發電廠機組向大容盤，高參數方向發展，閥門也隨著介質參數的提高，不斷地向高溫高壓方向發展。管道介質工作壓力的提高，要求閥門相應地改進密封結構，提高密封性能，采用新型密封面材料。為了簡化管路系統出現了一閥多用的組合閥門， 如啟動、減壓和安全三用的組合閥門。隨著自動控制的提高，實行集中控制和遙控，就對閥門的驅動裝置和執行機構提出了新的要求。

With the development of power plant units towards large capacity and high parameters, valves continue to develop towards high temperature and pressure with the improvement of medium parameters. The increase in working pressure of pipeline medium requires corresponding improvement of sealing structure and sealing performance of valves, and the use of new sealing surface materials. In order to simplify the pipeline system, a combination valve with multiple functions has emerged, such as a combination valve for starting, reducing pressure, and safety. With the improvement of automatic control and the implementation of centralized control and remote control, new requirements have been put forward for the driving device and actuator of valves.

對電站閥門的要求是使用性能好、強度高、操作方便、維修簡單、低噪音等。在發電廠的熱力系統中常常由于一個閥門發生故障造成整個系統或整個機組停止運行。

The requirements for power plant valves are good performance, high strength, easy operation, simple maintenance, and low noise. In the thermal system of power plants, the failure of one valve often causes the entire system or unit to stop operating.