Valves are pipeline accessories used to open and close pipelines, control flow direction, regulate and control the parameters of the conveying medium (temperature, pressure, and flow), and are very important components in pipeline systems. With the continuous improvement of various complete equipment processes and performance, the types of valves are also constantly changing and increasing. There are many classification methods for valves, and the commonly used ones are as follows.

 

01

Classified by purpose

1. Disconnecting function: used to cut off or connect the medium in the pipeline. Such as globe valves, gate valves, ball valves, plug valves, etc.

2. Regulating: Used to adjust the pressure or flow rate of the medium. Such as pressure reducing valves and regulating valves.

3. Distribution: Used to change the flow direction of the medium and play a distribution role. Such as three-way plug valves, three-way globe valves, etc.

4. Check function: used to prevent medium backflow. Like a check valve.

5. Safety use: When the medium pressure exceeds the specified value, discharge excess medium to ensure equipment safety. Such as safety valves and accident valves.

6. For gas blocking and drainage: retain gas and remove condensed water. Like a drain valve.

 

02

Classified by manipulation method

1. Manual valve: a valve that is manually operated using a handwheel, handle, lever, sprocket, gear, worm gear, etc.

2. Electric valve: a valve operated by electricity.

3. Pneumatic valve: a valve operated by compressed air.

4. Hydraulic valve: a valve operated by transmitting external force through liquids such as water and oil.

 

 

 

 

03

Classified by structure

Ball valve: The valve core moves along the centerline of the valve seat. Gate valve: The movement direction of the valve core (i.e. gate) is perpendicular to the flow direction of the medium. Globe valve: used to cut off or connect pipeline media. Plug valve: including three-way and four-way plug valves. Butterfly valve: used to regulate the pressure or flow rate of the medium. Diaphragm valve: used to prevent medium backflow or change the flow direction of the medium. Check valve: used to prevent medium backflow. Throttle valve: used to regulate the pressure or flow rate of the medium. Safety valve: used to discharge excess medium when the pressure exceeds the limit value, ensuring equipment safety. Pressure reducing valve: used to regulate the pressure of the medium.

 

04

Classified by nominal diameter

1. Small caliber valve: a valve with a nominal diameter less than 40 millimeters.

2. Medium caliber valves: valves with nominal diameters ranging from 50 to 300 millimeters.

3. Large caliber valves: valves with nominal diameters ranging from 350 to 1200 millimeters.

4. Extra large caliber valves: valves with a nominal diameter greater than 1400 millimeters.

 

Table 1-1 Comparison of nominal diameter and nominal diameter of valves

 

05

Classified by structural characteristics

1. Cut off valve shape: The opening and closing components move along the centerline of the valve seat.

2. Gate shape: The opening and closing components move along the centerline perpendicular to the valve seat.

3. Plug shaped: The opening and closing component is a plunger or ball that rotates around its own centerline.

4. Swing shape: The opening and closing member rotates around an axis outside the valve seat.

5. Disc shaped: The opening and closing member is a disc that rotates around the axis inside the valve seat.

6. Sliding valve shape: The opening and closing components slide in a direction perpendicular to the channel.

 

Figure 1-1 Schematic Diagram of Valve Structure Characteristics

 

06

Classified by pressure

1. Vacuum valve: a valve with an absolute pressure less than 1 kilogram.

2. Low pressure valve: a valve with a nominal pressure less than 16 kilograms.

3. Medium pressure valve: a valve with a nominal pressure of 25-64 kilograms.

4. High pressure valve: a valve with a nominal pressure of 100-800 kilograms.

5. Ultra high pressure: Valves with a nominal pressure of 1000 kilograms or more.

 

Table 1-2 Comparison Table of Valve Pressure Grades

 

07

Classified by medium temperature

1. Ordinary valve: suitable for valves with medium working temperatures ranging from -40 to 450 ℃.

2. High temperature valve: Suitable for valves with medium working temperatures ranging from 450 to 600 ℃.

3. Heat resistant valve: Suitable for valves with medium working temperature above 600 ℃.

4. Low temperature valve: Suitable for valves with medium working temperatures ranging from -40 to -70 ℃.

5. Cryogenic valve: Suitable for valves with medium working temperatures ranging from -70 to -196 ℃.

6. Ultra low temperature valve: suitable for valves with medium working temperature below -196 ℃.

 

08

Classified by connection method

1. Threaded connection valve: The valve body has internal or external threads and is connected to the pipeline thread

2. Flange connected valve: The valve body is equipped with a flange and connected to the pipeline flange.

3. Welded connection valve: The valve body has a welding groove and is welded to the pipeline.

4. Clamp connected valve: The valve body has a clamp and is connected to the pipeline clamp.

5. Card sleeve connection valve: It is connected to the pipeline using a card sleeve. 6. Clamp connection valve: a connection form that directly clamps the valve and two ends of the pipeline together with bolts.

 

09

Classification by valve body material

1. Metal material valve: Its valve body and other parts are made of metal materials. Such as cast iron valves, cast steel valves, alloy steel valves, copper alloy valves, aluminum alloy valves, lead alloy valves, titanium alloy valves, Monel alloy valves, etc. 2. Non metallic material valves: The valve body and other parts are made of non-metallic materials. Such as plastic valves, enamel valves, ceramic valves, fiberglass valves, etc.

 

The above categories cover the main types of valves and are applicable to general valves in industrial and civil engineering. Classification is not absolute, it can also be classified from other perspectives, but mastering these basic classifications is very beneficial for us to understand the wide variety of valve categories.