The choice of valve body is the most important link in the selection of diaphragm valve. There are many types of diaphragm valve body, commonly used through single seat, through double seat, Angle, diaphragm, small flow, tee, eccentric rotation, butterfly, sleeve type, ball and so on 10 kinds. Before choosing the valve, carefully analyze the media, process conditions and parameters of the control process, collect enough data to understand the requirements of the diaphragm valve system, and determine the type of valve to be used according to the collected data. In the specific selection, it can be considered from the following aspects:
(1) The spool shape structure is mainly considered according to the selected flow characteristics and unbalance force and other factors.
(2) Wear resistance When the fluid medium is a suspension containing high concentration of wear particles, the spool and seat joint surface will be severely friction each time it is closed. Therefore, the flow path of the valve should be smooth, and the internal material of the valve should be hard.
(3) Corrosion resistance due to the corrosive medium, in the case of meeting the adjustment function, try to choose simple structure valve.
(4) The temperature and pressure of the medium when the temperature and pressure of the medium are high and the change is large, the material of the spool and seat should be selected by the small change of temperature and pressure of the valve.
(5) Prevent flash evaporation and cavitation Flash evaporation and cavitation only occur in liquid media. In the actual production process, flash and cavitation not only affect the calculation of flow coefficient, but also form vibration and noise, so that the service life of the valve is shortened, so the valve should be prevented from flash and cavitation when selecting the valve.