Comparison between Pneumatic Control Valve and Hydraulic Valve

£¨1£© Different energy sources are used

Pneumatic components and devices can adopt the method of centralized gas supply from air compression stations, and adjust the working pressure of their respective pressure reducing valves according to different usage requirements and control points. Hydraulic valves are equipped with return oil pipelines to facilitate the collection of used hydraulic oil in the oil tank. Pneumatic control valves can directly discharge compressed air into the atmosphere through exhaust ports. 

£¨2£© Different requirements for leakage

Hydraulic valves have strict requirements for outward leakage, but allow for a small amount of leakage inside the components. For pneumatic control valves, internal leakage is generally not allowed except for gap sealed valves. Internal leakage of pneumatic valves poses a risk of accidents. For pneumatic pipelines, a slight leakage is allowed; The leakage of hydraulic pipelines will cause a decrease in system pressure and pollution to the environment. 

£¨3£© Different requirements for lubrication

The working medium of the hydraulic system is hydraulic oil, and there is no lubrication requirement for hydraulic valves; The working medium of pneumatic systems is air, which has no lubricity, so many pneumatic valves require oil mist lubrication. The parts of the valve should be made of materials that are not easily corroded by water, or necessary rust prevention measures should be taken. 

£¨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 10 bar, with a few reaching up to 40 bar. But the working pressure of hydraulic valves is very high (usually within 50Mpa). If the pneumatic valve is used beyond the maximum allowable pressure. Serious accidents often occur. 

£¨5£© Different usage characteristics

Generally, pneumatic valves have a more compact structure, lighter weight, are easier to integrate and install than hydraulic valves, and have a higher operating frequency and longer service life. Pneumatic valves are developing towards low power and miniaturization, and low-power solenoid valves with a power of only 0.5W have emerged. It can be directly connected to microcomputers and PLC programmable controllers, or installed on printed circuit boards together with electronic devices. It can be connected to the pneumatic circuit through a standard board, saving a lot of wiring. It is suitable for pneumatic industrial robots, complex production and assembly lines, and other occasions. 

3¡¢ Structural characteristics of pneumatic control valves

The structure of a pneumatic control valve can be decomposed into two parts: the valve body (including the valve seat and valve hole, etc.) and the valve core. According to the relative position of the two, there are two types: normally closed and normally open. Valves can be classified structurally into three types: globe valves, sliding column valves, and sliding plate valves.