Differences Between Pneumatic and Hydraulic Directional Control Valves

Update:04 Mar 2022

Comparison of Pneumatic Control Valves and Hydraulic Va […]

Comparison of Pneumatic Control Valves and Hydraulic Valves (1) Different energy sources Pneumatic components and devices can adopt the method of centralized air supply in the air compressor station, and adjust the working pressure of their respective pressure reducing valves according to different use requirements and control points. Hydraulic valves are equipped with oil return lines to facilitate the collection of used hydraulic oil in the oil tank. The pneumatic control valve can directly discharge the compressed air to the atmosphere through the exhaust port.
(2) Different requirements for leakage Hydraulic valves have strict requirements on external leakage, but a small amount of leakage inside the components is allowed. For pneumatic control valves, in principle, internal leakage is not allowed, except for gap-sealed valves. Risk of accident due to internal leakage of pneumatic valves. For the pneumatic pipeline, a little leakage is allowed; while the leakage of the hydraulic pipeline will cause the system pressure to drop and the environment to be polluted.
(3) Different requirements for lubrication The working medium of the hydraulic system is hydraulic oil, and the hydraulic valve has no requirement for lubrication; the working medium of the pneumatic system is air, and the air has no lubricity, so many pneumatic valves require oil mist lubrication. The parts of the valve should choose materials that are not easily corroded by water, or take necessary anti-rust measures.
(4) Different pressure ranges The working pressure range of pneumatic valves is lower than that of hydraulic valves. The working pressure of pneumatic valves is usually within 10bar, and a few can reach within 40bar. But the working pressure of hydraulic valve is very high (usually within 50Mpa). If the pneumatic valve is used above the maximum allowable pressure. Serious accidents often occur.
(5) Different characteristics of use Generally, pneumatic valves are more compact in structure and lighter in weight than hydraulic valves, and are easy to integrate and install. The valve has a high working frequency and a long service life. Pneumatic valves are developing in the direction of low power and miniaturization, and low-power solenoid valves with only 0.5W of power have appeared. It can be directly connected with microcomputer and PLC programmable controller, and can also be installed on the printed circuit board together with electronic devices, and the gas-electric circuit is connected through the standard board, which saves a lot of wiring, and is suitable for pneumatic industrial manipulators, complex production and manufacturing. assembly line, etc.


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