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The regulating valve is often called the control valve. It is a valve device that changes the fluid flow by receiving the control signal output by the regulating control unit and then operating with power. A regulating valve generally consists of an actuator and a valve. According to the power used by its matching actuator, the control valve can be divided into three types: pneumatic control valve, electric control valve and hydraulic control valve, that is, the pneumatic control valve with compressed air as the power source, and the electric control valve with electricity as the power source. Regulating valve is an electro-hydraulic regulating valve powered by the pressure of liquid medium (such as oil, etc.). In addition, according to its function and characteristics, there are three types: linear characteristic, equal percentage characteristic and parabolic characteristic. Fieldbus type regulating valve, etc.
There are many types of valve bodies for regulating valves. The commonly used types of valve bodies are straight-through single-seater, straight-through double-seater, angle, diaphragm, small flow, three-way, eccentric rotation, butterfly, sleeve type, spherical, etc. When making a specific selection, the following considerations can be made:
(1) Spool shape and structure
It is mainly considered based on factors such as the selected flow characteristics and unbalanced forces.
(2) Wear resistance
When the fluid medium is a suspension containing a high concentration of abrasive particles, the internal material of the valve is hard.
(3) Corrosion resistance
Because the medium is corrosive, try to choose a valve with a simple structure.
(4) The temperature and pressure of the medium
When the temperature and pressure of the medium are high and change greatly, the valve whose core and seat material are less affected by temperature and pressure should be selected.
(5) Prevent flashing and cavitation
Flashing and cavitation only occur in liquid media. In the actual production process, flashing and cavitation will cause vibration and noise, shortening the service life of the valve, so the valve should be prevented from flashing and cavitation when selecting the valve.
The above five points describe how to choose the body type of the regulating valve from the shape and structure of the valve core, wear resistance, corrosion resistance, medium temperature and pressure, and prevention of flashing and cavitation.
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