Briefing of Pneumatic

Pneumaticsis the branch of engineering that uses gas or compressed air.Pneumatic systems used in industry are usually powered by compressed air or compressed inert gas.A centrally located electric compressor powers cylinders,air motors,pneumatic actuators,and other pneumatic equipment.Pneumatic systems controlled by manual or automated solenoid valves are chosen when they offer a lower cost, more flexible or safer alternative to electric motors and hydraulic actuators.Pneumatics also have applications in dentistry, construction,mining and other fields.

Gases used in pneumatic systems 

Pneumatic systems in stationary installations such as factories use compressed air because a sustainable supply can be achieved by compressing the atmosphere.The air is usually dehydrated and a small amount of oil is added at the compressor to prevent corrosion and lubricate the mechanical parts.Users of factory-installed pneumatic power do not have to worry about toxic leaks because the gas is usually just air.Any compressed gas other than air is a suffocation hazard-including nitrogen,which is 78 percent air.Compressed oxygen (about 21% of air) does not suffocate,but is not used in pneumatic equipment because it is a fire hazard,is more expensive, and has no performance advantage over air.Smaller or self-contained systems may use other compressed gases that present a suffocation hazard,such as nitrogen-often referred to as OFN (oxygen-free nitrogen) when supplied in cylinders.Portable pneumatic tools and small vehicles,such as Robot vs.Machine and other hobbyist applications,are often powered by compressed carbon dioxide because containers designed to hold it,such as soda cans and fire extinguishers,are readily available and there is a gap between the liquid and the gas.The phase change made it possible to obtain larger volumes of compressed gas from lighter containers than needed for compressed air.Carbon dioxide is a smothering agent and may pose a freezing hazard if not vented properly.

• Comparison with hydraulic systems

  Both pneumatics and hydraulics are applications of fluid power.Pneumatics use an easily compressible gas,such as air or a suitable pure gas, while hydraulics use a relatively incompressible liquid medium, such as oil.Most industrial pneumatic applications use pressures of approximately 80 to 100 psi (550 to 690 kPa).Hydraulic applications typically use 1,000 to      5,000 psi (6.9 to 34.5 MPa),but special applications may exceed 10,000 psi (69 MPa).

• Advantages of aerodynamics

  Simplicity of Design and Contro-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 even if the power goes out,the machine can still run for a certain period of time.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 compressible,minimizing spring action.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 once:lubrication,cooling and power transmission.