Advantages of pneumatics

Simplicity of Design and Control Machines can be easily designed using standard cylinders and other components and operated  with simple on-off controls.Reliability-Pneumatic systems typically have a long life and require little maintenance.Since the gas is compressible, the device is less susceptible to shock damage.Gas absorbs excess force whereas fluid in a hydraulic system transmits force directly.Compressed gas can be stored, so if the power goes out, the machine can still run for a while.Safe-Very low fire potential compared to hydraulic fluids.New machines are usually overload safe within certain limits.

Advantages of hydraulics

Fluid does not absorb any supplied energy.

• Ability to move higher loads and provide lower forces due to incompressibility.Hydraulic working fluid is virtually incompressible, so spring action is minimal.When hydraulic fluid flow stops, the slightest movement of the load relieves pressure on the load; there is no need to "bleed" pressurized air to relieve pressure on the load.

• Responsive compared to pneumatic.

• Provides more power than pneumatics.Can also be used for multiple purposes at the same time: lubrication, cooling and power transmission.

Pneumatic logic

Pneumatic logic systems (sometimes called air logic controls) are sometimes used to control industrial processes and consist of major logic units such as:

• And unit

• Or unit

• Relay or booster

• Locking device

• Timer unit

• Fluid amplifiers with no moving parts other than the air itself.Pneumatic logic is a reliable and practical method of industrial process control.In recent years, these systems have been largely replaced by electronic control systems in new installations due to the smaller size, lower cost, higher precision and greater functionality of digital control.Pneumatics are still used where upgrade cost or safety factors dominate.

Compressed air

Compressed air is air held at a pressure greater than atmospheric pressure.Compressed air is an important medium for transferring energy in industrial processes.It is used for electric tools such as hammers, drills, and wrenches, atomizes paint, operates cylinders for automation, and can also be used to propel vehicles.Compressed air brakes make the operation of large rail trains safer and more efficient. Compressed air brakes are also used on large road vehicles.Compressed air is used as breathing gas by underwater divers. It can be carried by the diver in a high-pressure diving cylinder, or it can be supplied at lower pressure from the surface through an air line or the diver's umbilical cord.Similar arrangements are used in respirators used by firefighters, mine rescuers, and industrial workers in hazardous environments.In Europe, 10% of all industrial electricity consumption is used to produce compressed air the equivalent of 80 TWh per year.The industrial use of piped compressed air for power transmission was developed in the mid-19th century; unlike steam, compressed air can be piped for long distances without losing pressure through condensation.An early major application of compressed air was the drilling of the Mont Cenis tunnel in Italy and France in 1861, where a 600 kPa (87 psi) compressed air unit powered a pneumatic drill, greatly increasing productivity compared to previous manual drilling methods. Compressed air drilling rigs were used in American mines in the 1870s.In 1869, George Westinghouse invented the train air brake; these brakes greatly increased the safety of railroad operations.In the 19th century, Paris installed a system of ductwork for the municipal distribution of compressed air to power machines and drive generators for lighting.Early air compressors were steam driven, but in some places compressed air was obtained directly from the power of falling water.