(1) Straight through single-seat control valve: This valve is the most widely used, with some of the leaks? Allowable pressure differential? Flow complex, simple structure, it is suitable for leaks demanding, working pressure is small, clean media occasions, But the small size valve (nominal diameter DN <20 mm) can also be used for large pressure drop. Application should pay attention to proofing allowable pressure, to prevent the valve off. (2) through the two-seater control valve: with the direct single-seat control valve on the contrary, with a large leakage, allowable pressure differential characteristics, it applies to the lax leakage, working pressure large clean media occasions, the selection should be Note that the valve leakage meets the process control requirements. (3) sleeve valve: sleeve valve is divided into single seal and double seal two kinds of structure, the former is similar to the single-seat valve, suitable for single-seat valve occasions. The latter is similar to a two-seater valve, suitable for two-seater valve applications. Sleeve valve also has good stability, easy loading and unloading features, but the price is higher than the single-seat valve, double seat valve 50% to 200%, but also requires a special winding seal. Sleeve valve is second only to single seat valve, double seat valve is more widely used valve. (4) Angle valve: Throttle form is equivalent to a single-seat valve, but the valve body flow path is simple, suitable for some leakage requirements? Pressure difference is not big clean media occasions and require right-angle piping occasions. (5) three-way valve: It has three channels, instead of two through the single-seat valve for shunt and confluence and two-phase flow, the temperature difference is not greater than 150 ℃ occasions. When DN ≤ 80 mm, confluence valve can be used for shunt occasions. (6) diaphragm valve: flow path is simple, the diaphragm has a certain corrosion resistance, suitable for clean media, weak corrosive media two cut occasions. (7) Butterfly Valve: It is equivalent to take the pipe section to do the valve body, and the valve body is equivalent to the valve seat, so "self-cleaning" performance is good, the volume of some? Light weight. Suitable for dirty media and large diameter, large flow, pressure difference of the occasion. When Dn> 300 mm, usually by the butterfly valve to complete. (8) Ball Valve: The "O" ball valve is an unobstructive valve when fully open, and it is best for "self-cleaning" performance. It is suitable for two-position cutting occasion which is particularly unclean and contains fiber media. "V" -shaped ball valve has approximately equal percentage adjustment characteristics, suitable for unclean, fiber-containing media, adjustable control of large occasions. Ball valve is more expensive. (9) eccentric rotary valve: between the butterfly valve and the valve between the valve, "self-cleaning" good performance, good regulation, but also cut off, it is suitable for clean media, leakage requires a small regulatory occasions, but the valve price More expensive. The first six of these nine products are straight-stroke control valves and the last three are angle-travel control valves. As a control valve of the user, we must clarify their characteristics and precautions. Various types of modified products, improved products are evolved in these 9 categories of products come to understand these 9 categories of products to easily grasp the application of other products.