Valves are control components in fluid conveying systems that have functions such as cutoff, regulation, diversion, prevention of reverse flow, pressure stabilization, diversion, or overflow pressure relief. According to different classification standards, there are various types of valves, and each valve has its own unique features.

1. By valve type
Block valve: Block valve, also known as closed circuit valve, is used to connect or cut off the medium in the pipeline. Block valves include gate valves, globe valves, plug valves, ball valves, butterfly valves, and diaphragms.
Check valve: Check valve, also known as one-way valve or check valve, is used to prevent the medium in the pipeline from flowing back. The bottom valve for water pump suction and closing also belongs to the check valve category.
Safety valve: The function of safety valves is to prevent the medium pressure in the pipeline or device from exceeding the specified value, thereby achieving the purpose of safety protection.
Regulating valves: Regulating valves include regulating valves, throttle valves, and pressure reducing valves, which are used to regulate the pressure, flow rate, and other parameters of the medium.
Diverter valve: Diverter valves include various distribution valves and drain valves, which are used to distribute, separate, or mix the medium in the pipeline.

2. Classification by nominal pressure
Vacuum valve: refers to the valve whose working pressure is lower than the standard atmospheric pressure.
Low pressure valve: refers to a valve with a nominal pressure PN ≤ 1.6Mpa.
Medium pressure valve: refers to a valve with a nominal pressure PN of 2.5, 4.0, and 6.4Mpa.
High pressure valve: refers to a valve with a working pressure PN of 10-80Mpa.
Ultra high pressure valve: refers to a valve with a nominal pressure PN ≥ 100Mpa.

3. Classification by operating temperature
Ultra low temperature valve: used for valves with medium working temperature t<-100 ℃.
Low temperature valve: used for valves with medium working temperature -100 ℃ ≤ t ≤ -40 ℃.
Normal temperature valve: used for valves with medium working temperature -40 ℃ ≤ t ≤ 120 ℃.
Medium temperature valve: used for medium working temperature of 120 ℃
High temperature valve: used for valves with medium working temperature t>450 ℃.

4. Classification by Drive Method
Automatic valve refers to a valve that does not require external force to drive, but relies on the energy of the medium itself to make the valve operate. Such as safety valves, pressure reducing valves, drain valves, check valves, automatic regulating valves, etc.
Power driven valve: Power driven valve can be driven by various power sources.
Electric valve: A valve that is driven by electricity.
Pneumatic valve: A valve driven by compressed air.
Hydraulic valve: A valve that is driven by the pressure of a liquid such as oil. In addition, there are combinations of the above driving methods, such as pneumatic electric valves.
Manual valve: With the help of a handwheel, handle, lever, and sprocket, the manual valve is manually operated to operate the valve. When the valve has a large opening and closing torque, this wheel or worm gear reducer can be set between the handwheel and the valve stem. If necessary, universal joint and transmission shaft can also be used for remote operation.

5. Classification by nominal diameter
Small diameter valve: valve with a nominal diameter DN ≤ 40mm.

Medium diameter valve: A valve with a nominal diameter DN of 50-300mm.
Large diameter valve: A valve with a nominal valve DN of 350~1200mm.
Extra large diameter valve: valve with a nominal diameter DN ≥ 1400mm.

6. Classification by structural features
Gate valve: The opening and closing parts (valve discs) are driven by the valve stem to move up and down along the centerline of the valve seat;
Plug valve: The opening and closing parts (gate valves) are driven by the valve stem to move up and down along the centerline perpendicular to the valve seat;
Plug valve: The opening and closing parts (cone or ball) rotate around their own centerline;
Swing valve: The opening and closing parts (valve discs) rotate around the axis outside the seat;
Butterfly valve: The opening and closing parts (discs) rotate around a fixed axis inside the valve seat;
Slide valve: The opening and closing components slide in a direction perpendicular to the channel.

7. Classification by Connection Method
Threaded valve: The valve body is equipped with internal or external threads, which are connected to the pipeline threads.
Flange connected valve: The valve body is equipped with a flange and connected to the pipeline flange.
Welding connection valve: The valve body has a welding groove and is welded to the pipeline.
Clamp connection valve: The valve body is equipped with a clamp and connected to the pipeline clamp.
Ferrule connected valve: connected to the pipeline using ferrule.
Clamp connection valve: a connection form where the valve and two pipes are directly clamped together with bolts.

8. Classification by valve body material
Metal material valve: Its valve body and other parts are made of metal material. Such as cast iron valves, carbon steel valves, alloy steel valves, copper alloy valves, aluminum alloy valves, lead alloy valves, titanium alloy valves, Monel alloy valves, etc.
Non metallic valve: Its valve body and other parts are made of non-metallic materials. Such as plastic valves, ceramic valves, lined valves, fiberglass valves, etc.
Metal valve body lined valve: The valve body is made of metal, and the main surfaces inside that come into contact with the medium are lined, such as rubber lined valves, plastic lined valves, ceramic lined valves, etc.