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(1) Straight-through single-seat control valve: This valve is widely used, and has the characteristics of a little leakage and a complex flow path and simple structure, so it is suitable for clean medium occasions with strict leakage requirements and small working pressure difference, but small specifications Special valves (nominal diameter DN < 20 mm) can also be used in occasions with large pressure differences. During the application, attention should be paid to proofreading the allowable pressure difference to prevent the valve from being closed.
(2) Straight-through double-seat control valve: Contrary to the straight-through single-seat control valve, it has the characteristics of large leakage and large allowable pressure difference, so it is suitable for clean medium occasions with less strict leakage requirements and large working pressure difference. Pay attention to whether the valve leakage meets the process control requirements.
(3) Diaphragm valve: The flow path is simple, and the diaphragm has a certain corrosion resistance, which is suitable for two-position cut-off occasions of unclean medium and weakly corrosive medium.
(4) Butterfly valve: It is equivalent to taking a straight pipe section as the valve body, and the valve body is equivalent to the valve seat, so the “self-cleaning” performance is good, the volume is small and the weight is light. Suitable for unclean media and occasions with large diameter, large flow, and large pressure difference. When Dn>300 mm, it is usually done by butterfly valve.
(5) Ball valve: “O” type ball valve is a non-blocking valve when it is fully opened. It has better “self-cleaning” performance and is suitable for two-position cut-off occasions that are particularly dirty and contain fibrous media. The “V” shaped ball valve has an approximate equal percentage adjustment characteristic, and is suitable for control occasions with unclean, fibrous media and large adjustable ratio. Ball valves are more expensive.
(6) Eccentric rotary valve: This valve is between a butterfly valve and a ball valve. It has good “self-cleaning” performance, good adjustment performance, and can also be cut off. more expensive.
(7) Sleeve valve: Sleeve valve is divided into two structures: single seal and double seal. The former is similar to single seat valve and is suitable for single seat valve occasions. The latter is similar to a double-seat valve and is suitable for double-seat valve applications. The sleeve valve also has the characteristics of good stability and convenient assembly and disassembly, but the price is 50% to 200% higher than that of single-seat valve and double-seat valve, and it also needs a special winding gasket. Sleeve valve is the most widely used valve after single seat valve and double seat valve.
(8) Angle valve: The throttling form is equivalent to a single-seat valve, but the flow path of the valve body is simple, and it is suitable for clean medium occasions requiring some leakage and small pressure difference and occasions requiring right-angle piping.
(9) Three-way valve: It has 3 channels and can replace two straight-through single-seat valves. It is used for diversion and confluence and two-phase flow, and the temperature difference is not greater than 150 ℃. When DN≤80 mm, the confluence valve can be used in diversion occasions.
After mastering the above nine types of products, I believe that everyone can already deal with the application of control valves in most working conditions.
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