There are various types of valves according to different classification standards. The following is a detailed introduction to their classification and main parameters:
Classified by purpose
1. Block valve: used to cut off or connect the flow of medium.
-Gate valve: To cut off or connect fluid by moving the gate up and down
-Globe valve: To cut off or connect fluid by moving the valve disc along the centerline of the valve seat.
2. Regulating valve: used to regulate medium flow rate, pressure, etc.
-Ball valve: adjusts the flow rate by rotating the ball.
-Butterfly valve: adjusts the flow rate by rotating the butterfly plate.
3. Check valve: prevents medium backflow.
-Lift check valve: relies on the flow of medium to automatically open and close the valve disc.
-Swing check valve: The valve disc rotates around the pin shaft outside the valve seat to prevent backflow.
4. Safety valve: used to prevent system overpressure.
-Spring type safety valve: relies on spring force to control the opening pressure.
-Lever type safety valve: controls the opening pressure through a lever and a heavy hammer.
5. Pressure reducing valve: used to reduce system pressure.
-Direct acting pressure reducing valve: Control pressure by balancing the valve disc and spring.
-Pilot operated pressure reducing valve: regulates pressure through the coordination of the main valve and pilot valve.
Classified by structure
1. Plug valve: opens or closes the fluid channel by rotating the cylindrical or conical plug body.
2. Diaphragm valve: It isolates the medium through a flexible diaphragm and is suitable for corrosive media.
Classified by driving method
1. Manual valve: operated manually through handwheels, handles, etc.
2. Pneumatic valve: driven by compressed air.
3. Electric valve: driven by a motor.
4. Hydraulic valve: driven by hydraulic pressure.
main parameter
1. nominal diameter (DN): The inner diameter of a valve or connecting pipe, measured in millimeters (mm).
2. nominal pressure (PN): The maximum working pressure that a valve can withstand at room temperature, in megapascals (MPa) or bars (bar).
3. Applicable temperature: The temperature range within which the valve can function properly.
4. Applicable media: The working media considered in valve design, such as water, steam, oil, corrosive media, etc.
5. Material: The material of the main components of the valve, such as cast iron, cast steel, stainless steel, copper alloy, etc.
6. Connection method:
-Flange connection: Connect to the pipeline through a flange.
-Thread connection: Connect to the pipeline through threads.
-Welding connection: Connect to the pipeline through welding.
7. Driving methods: manual, electric, pneumatic, hydraulic, etc.
8. Flow coefficient (Cv or Kv): The fluid flow rate that a valve passes through under specified conditions, used to measure the valve's flow capacity.
9. Leakage level: The maximum allowable leakage of the valve in the closed state.
Typical valves and their parameter examples
1. Gate valve:
-Nominal diameter: DN50-DN2000
-Nominal pressure: PN1.0-PN25
-Applicable temperature: -20 ° C -425 ° C
-Materials: cast iron, carbon steel, stainless steel
2. Ball valve:
-Nominal diameter: DN6-DN1400
-Nominal pressure: PN1.6-PN32
-Applicable temperature: -196 ° C -450 ° C
-Materials: stainless steel, carbon steel, plastic
3. Butterfly valve:
-Nominal diameter: DN40-DN2400
-Nominal pressure: PN0.6-PN4.0
-Applicable temperature: -40 ° C -300 ° C
-Materials: cast iron, cast steel, stainless steel, aluminum alloy
Through the detailed introduction of the above classification and parameters, we can better understand the characteristics and scope of application of different valves, and select suitable valves to apply under specific operating conditions.