The role and classification of valves
Valves have many functions. Different valves should use different valves. Different types of valves have different configurations, and these functions are effective means to control the process and ensure safety. Valves are generally divided into automatic valves and drive valves. Automatic valves (such as safety valves, pressure reducing valves, steam traps, check valves) rely on changes in the pressure of the device or pipeline medium to achieve the purpose of opening and closing. The driving valve (gate valve, globe valve, ball valve, butterfly valve) and the like are regulated by the driving device (manual, electric, hydraulic, pneumatic, etc.) to adjust the pressure, flow and direction of the medium in the pipeline. Due to the different pressure, temperature, flow and physical and chemical properties of the medium, the control requirements and the use requirements of the device and the piping system are also different, so the functions of the valves are also different.
Shut-off valve: A shut-off valve, also known as a closed-circuit valve, is used to switch on or off the medium in the pipeline. Cut-off valves include gate valves, globe valves, plug valves, ball valves, butterfly valves, and diaphragm valves. <br />
Regulating valve: The regulating valve includes a regulating valve, a throttle valve and a pressure reducing valve, and its function is to adjust parameters such as pressure and flow of the medium.
Check valve: Check valve, also known as check valve or check valve, is used to prevent backflow of media in the pipeline. The bottom valve of the water pump suction is also a check valve.
Safety valve: The function of the safety valve is to prevent the pressure of the medium in the pipeline or device from exceeding the specified value, so as to achieve the purpose of safety protection.
Diverter: The diverter valve includes various distribution valves and traps, etc., which function to distribute, separate or mix the medium in the pipeline.
Exhaust valve: Exhaust valve is an indispensable auxiliary component in the pipeline system. It is often installed at the commanding height or elbow, eliminating excess gas in the pipeline, improving the efficiency of the pipeline and reducing energy consumption.
An important function of the valve is the cut-off effect. It is to cut off (turn off) the fluid in the pipeline and not to circulate it. Under normal circumstances, the valves of various pipelines mainly serve as a cut-off function.
Another important function of the valve is to adjust the flow rate, adjust the flow, temperature, pressure, liquid level and other parameters in the pipeline according to the requirements of the working conditions or the requirements of use. The control of this flow depends on the opening degree of the valve. adjust.
Some pipelines require the medium to flow in one direction, and do not allow backflow or reversal. This requires the use of a non-reversing valve (or a one-way valve). It refers to a valve that automatically opens and closes the valve flap by means of the flow of the medium itself, and is used to prevent the backflow of the medium. It belongs to an automatic valve, and its main function is to prevent the medium from flowing backward, prevent the pump and the drive motor from being reversed, and the container medium is discharged put.
4. Security role
In order to prevent an explosion accident from exceeding the pressure limit of the container when the fluid pressure in the high-pressure vessel is too high, a valve capable of automatically releasing pressure at a certain pressure is installed on the container, which is generally called a safety valve. Safety valves are provided, for example, in boilers, compressed air storage tanks, and some high pressure reactors. This valve plays a role in ensuring safety.
5. Other effects
In addition to the above four functions, the valve has some functions, such as stabilizing the pressure of the system pressure; reducing the high pressure in front of the valve to a lower pressure decompression action, performing the pressure relief function of the venting, and discharging the sewage function. Sampling for sampling and analysis; and returning a portion of the fluid back to the previous process. There is also a steering valve (three-way valve, four-way valve, etc.) that transfers fluid to another line.