Control valve Handbook


The control valve, also known as the regulating valve, is the main execution unit instrument control valve in the industrial process control. By accepting the control signal output by the regulating control unit, the fluid flow is changed with the help of power operation. The control valve is generally composed of an actuator and a valve. According to the different control methods, the control valve can be divided into: switch or fixed value control valve, servo control valve, electro-hydraulic proportional control valve, digital control valve, electro-hydraulic digital valve and so on. The control valve is a high-precision instrument, so it is necessary to strictly follow the standards during use and maintenance, otherwise it is easy to cause irreparable damage to the machine. Today I will introduce the correct cleaning method of the control valve.


Disassembly and cleaning are the first steps in the maintenance of control valves. For the directional control valve failure caused by oil pollution caused by hydraulic oil pollution or granular impurities in the hydraulic oil, the failure can generally be eliminated by disassembly and cleaning, and the function of the hydraulic valve can be restored.


Common cleaning processes include:


(1) Disassembly. Although the various parts of the control valve are mostly connected by bolts, the control valve is designed for non-disassembly. If there is no special equipment or professional technology, forcible disassembly is likely to cause damage to the hydraulic valve. Therefore, it is necessary to master the structure of the control valve and the connection method between the parts before disassembly, and record the positional relationship between the parts during disassembly.


(2) Check and clean up. Check the dirt deposition on the valve body, valve core and other parts, and remove the concentrated dirt with cotton yarn, brush and non-metal scraper without damaging the working surface.


(3) Rough washing. Put the valve body, valve core and other parts on the tray of the cleaning box, heat and soak, and pass the compressed air into the bottom of the cleaning tank, and wash away the remaining dirt through the stirring effect of air bubbles. If conditions permit, ultrasonic cleaning can be used.


(4) Fine wash. High pressure positioning cleaning with cleaning liquid, and finally drying with hot air. Qualified enterprises can use existing cleaning agents, and organic cleaning agents such as diesel and gasoline can also be used on individual occasions.


(5) Assembly. Assemble according to the assembly diagram of the control valve or the parts assembly relationship recorded during disassembly. Be careful not to damage the parts during assembly. The original sealing material is easily damaged during disassembly and should be replaced during assembly.


Pay attention to the following issues when cleaning:


(1) For the dirt that has a long deposition time and is firmly pasted, do not scratch the mating surface when cleaning.

(2) Pay attention to safety when heating. Some inorganic cleaning liquids are toxic and can be poisoned by heating and volatilization, so they should be used with caution; organic cleaning liquids are flammable, pay attention to fire prevention.

(3) When choosing a cleaning fluid, pay attention to its corrosiveness to avoid corrosion to the valve body

(4) The cleaned parts should be kept carefully to avoid corrosion or re-contamination

(5) The assembled directional control valve can only be put into use after passing the test.


Hanjiu has been producing hydraulic products for more than ten years. The control valves they produce are of high quality and low price, and are well received. In addition, Hanjiu provides the most thoughtful and comprehensive service, and "customer first" is the philosophy they always adhere to. If you want to buy related products, come to Hanjiu's official website to have a look, there are the most complete varieties and the most cost-effective products! Hanjiu's products have always been trustworthy.



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