Pneumatic control system:
In the pneumatic system, pressurized gas is used to actuate instruments.
Carbon dioxide, nitrogen and high pressure air are the gasses most commonly used for this control. Gases are high pressurized using compressors and kept in tanks, which is usually compressed to thousands of pounds per square inch.
Pneumatic checks are also dependent on regulators connected to the gas tank. A regulator reduces the high pressure from the tank and lowers it to a more manageable pressure.
Hydraulic Control system:
Hydraulic systems work because of Pascal’s law, which states that an increase of pressure in any part of a confined fluid causes an equal increase of pressure throughout the container. If force is applied to one part of a hydraulic system, it travels through the hydraulic fluid to the rest of the system.
Difference between Pneumatic & Hydraulic control system:
The main difference between pneumatic and hydraulic control is one use air and the other liquid/oil as operating media respectively. Pneumatic control apply only small power, where hydraulic control can deliver to a large amount of power.
Pneumatic control is used for small factory instruments compare to hydraulic instrument used for small to heavy machine
Air can be compressed but liquid can’t so its needed more space.
| Control System | Advantages | Disadvantages |
|---|---|---|
| Pneumatic Control system | Simple components and no complex structure | Great distance lag can be a crucial setback with pneumatic controls |
| Easy to maintain | Slow response | |
| Useful in flame-proof applications | Difficult to operate in sub-normal temperatures | |
| Low cost of installation | Copper piping is vulnerable to damage | |
| Good reliability and reproducibility | Pipe-couplings can give rise to leaks in certain ambient conditions | |
| Speed of response is relatively slow but steady | ||
| Limited power capacity for large mass transfer | ||
| Hydraulic control system | More accurate result | Must be regularly check for leak |
| Large amounts of power with little input force. | Filters must be change frequently | |
| Provides constant force | Highly pressurized fluid | |
| They do not cause sparks, so hydraulic systems are safe in chemical plants and mines | High pressurized fluid can cause burn, bruises or the accidental injection of fluid into the body |