1. Classification by function and use

(1) truncation type: such as gate valve, globe valve, plug valve, ball valve, butterfly valve, needle valve, diaphragm valve, etc.(2) check class: such as check valve, check valve is also known as a check valve or check valve, check valve belongs to an automatic valve, its role is to prevent the reverse flow of the medium in the pipeline, to prevent the reversal of the pump and drive motor, and the leakage of the container medium.Pump suction off the bottom valve is also a check valve class.(3) Safety: such as safety valve, accident valve, etc.(4) regulating class: such as regulating valve, throttle valve and pressure reducing valve, its role is to adjust the pressure, flow and other parameters of the medium.(5) shunt type: such as distribution valve, three-way valve, trap.Its function is to distribute, separate or mix the medium in the pipeline.(6) Special purpose: such as pigging valve, vent valve, drain valve, exhaust valve, etc.Exhaust valve is an essential auxiliary element in pipeline system, widely used in boiler, air conditioning, oil and gas, water supply and drainage pipeline.It is often installed at the commanding point or elbow to eliminate the excess gas in the pipeline, improve the use efficiency of the pipeline road and reduce energy consumption.

2. Classified by nominal pressure

(1) Vacuum valve: refers to the valve whose working pressure is lower than standard atmospheric pressure.(2) low pressure valve: refers to the nominal pressure PN ≤1.6Mpa valve.(3) medium pressure valve: refers to the nominal pressure PN of 2.5Mpa, 4.0Mpa, 6.4Mpa valve.(4) high pressure valve: refers to the valve whose pressure PN is 10.0Mpa ~ 80.0Mpa.(5) ultra-high pressure valve: refers to the valve whose nominal pressure PN≥100.0Mpa.

3. Classification by working temperature

(1) ultra-low temperature valve: used for medium working temperature T<-101℃ valve.(2) low temperature valve: used for medium working temperature -101℃≤ T ≤-29℃ valve.(3) Normal temperature valve: used for medium working temperature -29℃<t<120℃ valve.(4) medium temperature valve: used for medium working temperature 120℃≤ T ≤425℃ valve (5) high temperature valve: used for medium working temperature T>425℃ valve.

4. Classify by driving mode

According to the driving mode, it is divided into automatic valves, power driven valves and manual valves

5. Classified by nominal diameter

(1) Small size valve: nominal diameter DN≤40mm valve.(2) Medium diameter valve: nominal diameter DN of 50 ~ 300mm valve.(3) large diameter valve: nominal valve DN 350 ~ 1200mm valve.(4) extra-large diameter valves: valves with nominal diameter DN≥1400mm.