Classification of Functions and Uses of Various Valves
Industrial valves were born after the invention of steam engine. In recent twenty or thirty years, due to the needs of petroleum, chemical industry, power station, metallurgy, shipbuilding, nuclear energy, aerospace and other aspects, higher requirements were put forward for valves, which lead to study and produce valves with high parameters, and their working temperatures ranged from ultra-low temperature -269℃ to high temperature 1200℃, even as high as 3430℃. The working pressure ranges from 1.33×10-8 Pa (1×10 - 10 mmHg) to 1460MPa; the valve size ranges from 1mm to 6000mm, and even reaches 9750mm.
The materials of valves have developed from cast iron and carbon steel to titanium and titanium alloy steel, as well as high-strength corrosion-resistant steel, low-temperature steel and heat-resistant steel valves. The driving mode of valves has developed from electric, pneumatic and hydraulic to program control, air counting and remote control. The processing technology of valves also ranges from ordinary machine tools to assembly lines and automatic lines.
According to the different functions of opening and closing valves, there are many classification methods of valves, and the following kinds are introduced here. Classified by function and purpose:
1.
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.
2.
Check valve:
Check valve is also called one-way valve or non-return valve, and its function is to prevent the medium in the pipeline from flowing backwards. The bottom valve of water pump suction switch is also a check valve.
3.
Safety valves: The function of safety valves is to prevent the medium pressure in pipelines or devices from exceeding the specified value, so as to achieve the purpose of safety protection.
4.
Regulating valves: The regulating valves include regulating valves, throttle valves and pressure reducing valves, and their functions are to regulate the pressure and flow of medium.
5.
Diverter valves: Diverter valves include various distribution valves and steam traps, which are used to distribute, separate or mix the medium in the pipeline.