According to the purpose and function classification Shut-off valve is mainly used to cut off or connect the media flow. Including gate valve, globe valve, diaphragm valve, ball valve, plug valve, butterfly valve, plunger valve, ball valve, needle valve and so on. Regulating valve is mainly used to regulate the flow of media, pressure and so on. Including the control valve, throttle, pressure reducing valve. Check valves are used to prevent backflow of media. Includes various configurations of check valves. Diverter valves are used to separate, distribute, or mix media. Including a variety of distribution valves and traps and other structures. Safety valves are used for the protection of the medium against overpressure. Including various types of safety valve. According to the main parameters (a) Press the classification vacuum valve working pressure is lower than the standard atmospheric pressure valve. Low pressure valve nominal pressure PN less than 1.6MPa valve. Medium pressure valve nominal pressure PN 2.5 ~ 6.4MPa valve. High pressure valve nominal pressure PN10.0 ~ 80.0MPa valve. High pressure valve nominal pressure PN greater than 100MPa valve. (B) by the temperature of the medium temperature valve t is greater than 450C. Medium temperature valve 120 C is less than t less than 450 C valve. Room temperature valve -40 C less than t less than 120 C of the valve. Cryogenic valve -100 C Less than t Less than -40 C valve. Cryogenic valve t is less than -100 C valve. (C) by the valve body material classification Non-metallic materials valves: such as ceramic valves, glass steel valves, plastic valves. Metal material valves: such as copper alloy valve, aluminum alloy valve, lead alloy valve, titanium alloy valve, Monel alloy valve cast iron valve, carbon steel valve, cast steel valve, low alloy steel valve, high alloy steel valve. Metal body lining valves: such as lead-lined valves, lined plastic valves, lined enamel valves. General taxonomy This taxonomy not only by principle, role and structure by the division, is currently the most common international and domestic classification methods. General sub-gate valves, globe valves, throttle valves, instrumentation valves, plunger valves, diaphragm valves, plug valves, ball valves, butterfly valves, check valves, pressure relief valve safety valve, Sewage valve and so on.