1. Classification of diaphragm valves:
Diaphragm valve according to the structure form can be divided into: weir type, straight flow, cut-off type, straight through type, gate type and right Angle type. The connection way is usually flange connection. According to the driving mode can be divided into manual, electric and pneumatic. Pneumatic drive is divided into normally open, normally closed and reciprocating three.
2. Selection guide of diaphragm valves:
(1) The shape and structure of the spool are mainly considered according to the selected flow characteristics and unbalanced force.
(2) Wear resistance When the fluid medium is a suspension containing high concentration of wear particles. The spool and seat joint surface will be subjected to severe friction every time it is closed. So the flow of the valve should be smooth, and the internal material of the valve should be hard.
(3) Corrosion resistance because of the corrosive medium, in the case of meeting the regulation function, as far as possible to choose the simple structure of the valve.
(4) The temperature and pressure of the medium when the temperature and pressure of the medium is high and changes greatly. The valve core and valve seat material should be selected by the temperature and pressure change small valve.
(5) Prevent flash and cavitation flash and cavitation only occur in liquid media. In the actual production process, the flash and cavitation not only affect the calculation of flow coefficient, but also form vibration and noise, which shorten the service life of the valve. Therefore, the valve should be prevented from flash and cavitation when choosing the valve.
(6) Manufacturers, we must choose regular large and professional.