20

2021

-

04

What is the function of valve

Author:


Valves are generally divided into automatic valves and driven valves. Automatic valves (such as safety valves, pressure reducing valves, steam traps and check valves) rely on medium pressure changes in equipment or pipelines to achieve the purpose of opening and closing. The pressure, flow and direction of the medium in the pipeline are adjusted by driving the valve (gate valve, globe valve, ball valve, butterfly valve, etc.) through a driving device (manual, electric, hydraulic, pneumatic, etc.). Since the pressure, temperature, flow rate and physical and chemical properties of the medium are different, the control requirements and usage requirements for equipment and pipeline systems are also different, so the functions of valves are also different.

Valves are generally divided into automatic valves and driven valves. Automatic valves (such as safety valves, pressure reducing valves, steam traps and check valves) rely on medium pressure changes in equipment or pipelines to achieve the purpose of opening and closing. The pressure, flow and direction of the medium in the pipeline are adjusted by driving the valve (gate valve, globe valve, ball valve, butterfly valve, etc.) through a driving device (manual, electric, hydraulic, pneumatic, etc.). Since the pressure, temperature, flow rate and physical and chemical properties of the medium are different, the control requirements and usage requirements for equipment and pipeline systems are also different, so the functions of valves are also different.

 

The function of valve
picture

 

1. Cut-off effect
The important function of the valve is the cut-off effect. It closes (closes) the fluid in the pipeline and does not allow it to flow. Generally, the valves of various pipelines mainly play a cut-off role.

 

 

2. Adjustment function
Another important function of the valve is to adjust the flow rate. According to the working conditions or requirements, the medium flow rate, temperature, pressure, liquid level and other parameters are adjusted. The flow control depends on the adjustment of the valve opening. [Electric regulating ball valve, electric regulating butterfly valve, pneumatic regulating ball valve, pneumatic regulating butterfly valve]
 
3. Anti-return function.
Some pipelines require medium flow to flow in one direction, and no reverse flow or rewind is allowed. This requires the use of a check valve (or one-way valve). It refers to a valve that automatically opens and closes the valve disc to prevent medium backflow. Belongs to an automatic valve. Its main function is to prevent the reverse flow of the medium, the reverse rotation of the pump and drive motor, and the discharge of the container medium.
 
4. Safety function: 
When the fluid pressure is too high, in order to prevent the pressure in the high-pressure container from exceeding the pressure limit of the container, an explosion may occur. Therefore, a valve that can automatically release pressure under a certain pressure is installed on the container, usually called a safety valve. For example, safety valves are installed on boilers, compressed air tanks and some high-pressure reactors. This valve plays a role in ensuring safety.
 
5. Other functions
In addition to the above four functions, the valve also has some functions, such as stabilizing the system pressure; decompressing the high pressure in front of the valve to reduce the pressure, depressurizing the exhaust, and discharging pollutants from the discharge function. Sampling is taken for analysis and observation; and a portion of the fluid is returned to the previous reflux process for reflux. There are also diverter valves (three-way valve, four-way valve, etc.) that divert fluid into another line.