Classification
Divided by power
Automatic valve: A valve that operates by relying on the force of the medium itself. Such as check valves, pressure reducing valves, drain valves, safety valves, etc.
Drive valve: a valve that relies on external forces such as manpower, electricity, fluid power, and pneumatic power to operate. Such as globe valves, throttle valves, gate valves, butterfly valves, ball valves, plug valves, etc.
Classified by structural characteristics

Classified by purpose
Shutoff valve: Cut off or connect pipeline medium. Such as globe valves, gate valves, ball valves, plug valves, etc;
Regulating valve: regulates the pressure or flow rate of the medium. Such as pressure reducing valves and regulating valves;
Check valve: prevents medium backflow. Like a check valve.
Distribution valve: Changes the flow direction of the medium and plays a distribution role. Such as three-way cocks, three-way globe valves, etc.
Safety valve: When the pressure exceeds the limit value, excess medium is discharged to ensure equipment safety. Such as safety valves and accident valves;
Gas blocking and drainage valve: retain gas and discharge condensate, such as a drain valve.
Shutoff valve: Cut off or connect pipeline medium. Such as globe valves, gate valves, ball valves, plug valves, etc;
Regulating valve: regulates the pressure or flow rate of the medium. Such as pressure reducing valves and regulating valves;
Check valve: prevents medium backflow. Like a check valve.
Distribution valve: Changes the flow direction of the medium and plays a distribution role. Such as three-way cocks, three-way globe valves, etc.
Safety valve: When the pressure exceeds the limit value, excess medium is discharged to ensure equipment safety. Such as safety valves and accident valves;
Gas blocking and drainage valve: retain gas and discharge condensate, such as a drain valve.
According to the manipulation method
Manual valve: a valve that is manually operated using handwheels, handles, levers, sprockets, gears, worm gears, etc.
Electric valve: A valve operated by means of electricity.
Pneumatic valve: A valve operated by compressed air.
Hydraulic valve: A valve operated by transmitting external forces through liquids such as water and oil.
Divided by pressure
Vacuum: Valves with an absolute pressure less than 1 kg/cm2.
Low pressure: Valves with a nominal pressure less than 16 kg/cm2.
Medium pressure: valve with a nominal pressure of 25-64 kg/cm2.
High pressure: valve with a nominal pressure of 100-800 kg/cm2.
Ultra high: valves with a nominal pressure of 1000 kg/cm2 or more.
By medium temperature
Ordinary valves: valves with a temperature range of -40 to 450 ℃ (medium temperature)}.
High temperature valve: A valve with a medium temperature of 450 to 600 ℃.
Heat-resistant valve: Valves with a medium temperature above 600 ℃.
Low temperature valve: A valve with a medium temperature of -40 to -70 ℃.
Cryogenic valves: valves with a medium temperature of -70 to -196 ℃.
Ultra low temperature valve: Valves below -196 ℃ (medium temperature).
Divided by nominal diameter
Small caliber: Valves with a nominal diameter less than 40mm.
Medium diameter: Valves with a nominal diameter of 50 to 300 millimeters.
Large diameter: valves with nominal diameters ranging from 350 to 1200 millimeters.
Extra large diameter: valves with a nominal diameter greater than 1400 millimeters.
The above classifications are not absolute and can be classified from other perspectives. Only by mastering these basic classifications can we understand