Pneumatics
Encyclopedia
Pneumatic systems are extensively used in industry
Industry
Industry refers to the production of an economic good or service within an economy.-Industrial sectors:There are four key industrial economic sectors: the primary sector, largely raw material extraction industries such as mining and farming; the secondary sector, involving refining, construction,...
, where factories
Factory
A factory or manufacturing plant is an industrial building where laborers manufacture goods or supervise machines processing one product into another. Most modern factories have large warehouses or warehouse-like facilities that contain heavy equipment used for assembly line production...
are commonly plumbed with compressed air
Compressed air
Compressed air is air which is kept under a certain pressure, usually greater than that of the atmosphere. In Europe, 10 percent of all electricity used by industry is used to produce compressed air, amounting to 80 terawatt hours consumption per year....
or compressed inert gases. This is because a centrally located and electrically powered compressor
Gas compressor
A gas compressor is a mechanical device that increases the pressure of a gas by reducing its volume.Compressors are similar to pumps: both increase the pressure on a fluid and both can transport the fluid through a pipe. As gases are compressible, the compressor also reduces the volume of a gas...
that powers cylinders
Pneumatic cylinder
Pneumatic cylinders are mechanical devices which utilize the power of compressed gas to produce a force in a reciprocating linear motion....
and other pneumatic devices through solenoid valve
Solenoid valve
A solenoid valve is an electromechanical valve for use with liquid or gas. The valve is controlled by an electric current through a solenoid: in the case of a two-port valve the flow is switched on or off; in the case of a three-port valve, the outflow is switched between the two outlet ports...
s is often able to provide motive power in a cheaper, safer, more flexible, and more reliable way than a large number of electric motor
Electric motor
An electric motor converts electrical energy into mechanical energy.Most electric motors operate through the interaction of magnetic fields and current-carrying conductors to generate force...
s and actuator
Actuator
An actuator is a type of motor for moving or controlling a mechanism or system. It is operated by a source of energy, usually in the form of an electric current, hydraulic fluid pressure or pneumatic pressure, and converts that energy into some kind of motion. An actuator is the mechanism by which...
s.
Pneumatics also has applications in dentistry
Dentistry
Dentistry is the branch of medicine that is involved in the study, diagnosis, prevention, and treatment of diseases, disorders and conditions of the oral cavity, maxillofacial area and the adjacent and associated structures and their impact on the human body. Dentistry is widely considered...
, construction
Construction
In the fields of architecture and civil engineering, construction is a process that consists of the building or assembling of infrastructure. Far from being a single activity, large scale construction is a feat of human multitasking...
, mining
Mining
Mining is the extraction of valuable minerals or other geological materials from the earth, from an ore body, vein or seam. The term also includes the removal of soil. Materials recovered by mining include base metals, precious metals, iron, uranium, coal, diamonds, limestone, oil shale, rock...
, and other areas.
Examples of pneumatic systems and components
- Air brakesAir brake (road vehicle)Air brakes are used in trucks, buses, trailers, and semi-trailers. George Westinghouse first developed air brakes for use in railway service. He patented a safer air brake on March 5, 1872. Originally designed and built for use on railroad train application, air brakes remain the exclusive systems...
on busBusA bus is a road vehicle designed to carry passengers. Buses can have a capacity as high as 300 passengers. The most common type of bus is the single-decker bus, with larger loads carried by double-decker buses and articulated buses, and smaller loads carried by midibuses and minibuses; coaches are...
es and truckTruckA truck or lorry is a motor vehicle designed to transport cargo. Trucks vary greatly in size, power, and configuration, with the smallest being mechanically similar to an automobile...
s - Air brakesAir brake (rail)An air brake is a conveyance braking system actuated by compressed air. Modern trains rely upon a fail-safe air brake system that is based upon a design patented by George Westinghouse on March 5, 1872. The Westinghouse Air Brake Company was subsequently organized to manufacture and sell...
, on trainTrainA train is a connected series of vehicles for rail transport that move along a track to transport cargo or passengers from one place to another place. The track usually consists of two rails, but might also be a monorail or maglev guideway.Propulsion for the train is provided by a separate...
s - Air compressorsGas compressorA gas compressor is a mechanical device that increases the pressure of a gas by reducing its volume.Compressors are similar to pumps: both increase the pressure on a fluid and both can transport the fluid through a pipe. As gases are compressible, the compressor also reduces the volume of a gas...
- Air engines for pneumatically powered vehicles
- BarostatBarostatA barostat is a device used to maintain constant pressure in a closed chamber. Their main principle is providing constant pressures in a balloon by means of a pneumatic pump...
systems used in NeurogastroenterologyNeurogastroenterologyNeurogastroenterology is a research area in the field of Gastroenterology which regards interactions of the central nervous system and the gut - the so-called brain-gut axis. Important research focuses upon upward and downward neural connections and upon endocrine influences on gut function....
and for researching electricity - Cable jettingCable jettingCable jetting is a technique to install cables in ducts. It is commonly used to install cables with optical fibers in underground polyethylene ducts and is an alternative to pulling.-Pulling:...
, a way to install cables in ducts - Compressed-air engine and compressed-air vehicleCompressed-air vehicleA compressed-air vehicle is powered by an air engine, using compressed air, which is stored in a tank. Instead of mixing fuel with air and burning it in the engine to drive pistons with hot expanding gases, compressed-air vehicles use the expansion of compressed air to drive their pistons...
s - Gas-operated reloadingGas-operated reloadingGas-operation is a system of operation used to provide energy to operate autoloading firearms. In gas-operation, a portion of high pressure gas from the cartridge being fired is used to power a mechanism to extract the spent case and chamber a new cartridge. Energy from the gas is harnessed...
- Holman ProjectorHolman ProjectorThe Holman Projector was an anti-aircraft weapon used by the Royal Navy during World War II, primarily between early 1940 and late 1941. The weapon was proposed and designed by Holmans, a machine tool manufacturer based at Camborne, Cornwall...
, a pneumatic anti-aircraft weapon - Inflatable structures
- Lego pneumaticsLego pneumaticsLego pneumatics is a variety of Lego bricks which use air pressure and specialised components to perform various actions using the principles of pneumatics.-History:...
can be used to build pneumatic models
- Pipe organs:
- Electro-pneumatic actionElectro-pneumatic actionThe electro-pneumatic action is a control system for pipe organs, whereby air pressure, controlled by an electric current and operated by the keys of an organ console, opens and closes valves within wind chests, allowing the pipes to speak. This system also allows the console to be physically...
- Tubular-pneumatic actionTubular-pneumatic action"Tubular-pneumatic action" refers to an apparatus used in manypipe organs built during the late 19th and early 20th centuries. The term "tubular" refers to the extensive use of lead tubing to connect the organ's console to the valves that control the delivery of "wind" to the organ's pipes...
- Electro-pneumatic action
- Pneumatic actuatorPneumatic actuatorA pneumatic actuator converts energy into motion. The motion can be rotary or linear, depending on the type of actuator.Some types of pneumatic actuators include:*Tie rod cylinders*Rotary actuators*Grippers...
- Pneumatic air guns
- Pneumatic cylinderPneumatic cylinderPneumatic cylinders are mechanical devices which utilize the power of compressed gas to produce a force in a reciprocating linear motion....
- Pneumatic Launchers, a type of spud gun
- Pneumatic mail systems
- Pneumatic motorPneumatic motorA pneumatic motor or compressed air engine is a type of motor which does mechanical work by expanding compressed air. Pneumatic motors generally convert the compressed air to mechanical work through either linear or rotary motion...
- Pneumatic tire
- Pneumatic toolPneumatic toolA pneumatic tool or air tools is a tool driven by a gas, usually compressed air supplied by a gas compressor. Pneumatic tools can also be driven by compressed carbon dioxide stored in small cylinders allowing for portability...
s:- JackhammerJackhammerA jackhammer is a pneumatic tool that combines a hammer directly with a chisel that was invented by Charles Brady King. Hand-held jackhammers are typically powered by compressed air, but some use electric motors. Larger jackhammers, such as rig mounted hammers used on construction machinery, are...
used by road workers - Pneumatic nailgun
- Jackhammer
- Pressure regulatorPressure regulatorA pressure regulator is a valve that automatically cuts off the flow of a liquid or gas at a certain pressure. Regulators are used to allow high-pressure fluid supply lines or tanks to be reduced to safe and/or usable pressures for various applications....
- Pressure sensorPressure sensorA pressure sensor measures pressure, typically of gases or liquids. Pressure is an expression of the force required to stop a fluid from expanding, and is usually stated in terms of force per unit area. A pressure sensor usually acts as a transducer; it generates a signal as a function of the...
- Pressure switch
- Vacuum pumpVacuum pumpA vacuum pump is a device that removes gas molecules from a sealed volume in order to leave behind a partial vacuum. The first vacuum pump was invented in 1650 by Otto von Guericke.- Types :Pumps can be broadly categorized according to three techniques:...
Gases used in pneumatic systems
Pneumatic systems in fixed installations such as factories use compressed air because a sustainable supply can be made by compressing atmospheric air. The air usually has moisture removed and a small quantity of oil added at the compressor, to avoid corrosion of mechanical components and to lubricate them.Factory-plumbed, pneumatic-power users need not worry about poisonous leakages as the gas is commonly just air. Smaller or stand-alone systems can use other compressed gases which are an asphyxiation hazard, such as nitrogen
Nitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...
- often referred to as OFN (oxygen-free nitrogen), when supplied in cylinders.
Any compressed gas other than air is an asphyxiation hazard - including nitrogen, which makes up 77% of air. Compressed oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
(approx. 23% of air) would not asphyxiate, but it would be an extreme fire hazard, so is never used in pneumatically powered devices.
Portable pneumatic tools and small vehicles such as Robot Wars
Robot Wars (TV series)
Robot Wars is a British game show modelled on a US-based competition of the same name. It was broadcast on BBC Two from 1998 until 2003, with its final series broadcast on Five in 2003 and 2004. Additional series were filmed for specific sectors of the global market, including two series of Robot...
machines and other hobbyist applications are often powered by compressed carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
because containers designed to hold it such as soda stream canisters and fire extinguishers are readily available, and the phase change between liquid and gas makes it possible to obtain a larger volume of compressed gas from a lighter container than compressed air would allow. Carbon dioxide is an asphyxiant and can also be a freezing hazard when vented inappropriately.
Comparison to hydraulics
Both pneumatics and hydraulics are applications of fluid powerFluid power
Fluid power is the use of fluids under pressure to generate, control, and transmit power. Fluid power is subdivided into hydraulics using a liquid such as mineral oil or water, and pneumatics using a gas such as air or other gases...
. Pneumatics uses an easily compressible gas such as air or a suitable pure gas, while hydraulics
Hydraulics
Hydraulics is a topic in applied science and engineering dealing with the mechanical properties of liquids. Fluid mechanics provides the theoretical foundation for hydraulics, which focuses on the engineering uses of fluid properties. In fluid power, hydraulics is used for the generation, control,...
uses relatively incompressible liquid media such as oil. Most industrial pneumatic applications use pressures of about 80 to 100 psi (551.6 to 689.5 kPa). Hydraulics applications commonly use from 1000 to 5000 psi (6.9 to 34.5 MPa), but specialized applications may exceed 10000 psi (68.9 MPa).
Advantages of pneumatics
- Simplicity of Design And Control
- Machines are easily designed using standard cylinders & other components. Control is as easy as it is simple ON - OFF type control.
- Reliability
- Pneumatic systems tend to have long operating lives and require very little maintenance.
- Because gas is compressible, the equipment is less likely to be damaged by shock. The gas in pneumatics absorbs excessive force, whereas the fluid of hydraulics directly transfers force.
- Storage
- Compressed gas can be stored, allowing the use of machines when electrical power is lost.
- Safety
- Very low chance of fire (compared to hydraulic oil).
- Machines can be designed to be overload safe.
Advantages of hydraulics
- Liquid (as a gas is also a 'fluid') does not absorb any of the supplied energy.
- Capable of moving much higher loads and providing much higher forces due to the incompressibility.
- The hydraulic working fluid is basically incompressible, leading to a minimum of springSpring (device)A spring is an elastic object used to store mechanical energy. Springs are usually made out of spring steel. Small springs can be wound from pre-hardened stock, while larger ones are made from annealed steel and hardened after fabrication...
action. When hydraulic fluid flow is stopped, the slightest motion of the load releases the pressure on the load; there is no need to "bleed off" pressurized air to release the pressure on the load.
Pneumatic logic
Pneumatic logic systems (sometimes called air logic control) are often used to control industrial processes, consisting of primary logic units such as:- AndLogical conjunctionIn logic and mathematics, a two-place logical operator and, also known as logical conjunction, results in true if both of its operands are true, otherwise the value of false....
Units - OrLogical disjunctionIn logic and mathematics, a two-place logical connective or, is a logical disjunction, also known as inclusive disjunction or alternation, that results in true whenever one or more of its operands are true. E.g. in this context, "A or B" is true if A is true, or if B is true, or if both A and B are...
Units - 'Relay or Booster' Units
- Latching Units
- 'Timer' Units
- Sorteberg relaySorteberg relayThe Sorteberg relay, or Sorteberg force bridge pneumatic relay is a form of analog pneumatic computer, calibrated to calculate a predefined function. They were sold by Sorteberg Controls Corp....
- fluidicsFluidicsFluidics or Fluidic logic is the use of a fluid to perform analog or digital operations similar to those performed with electronics.The physical basis of fluidics is pneumatics and hydraulics, based on the theoretical foundation of fluid dynamics...
amplifiers with no moving parts other than the air itself
Pneumatic logic is a reliable and functional control method for industrial processes. In recent years, these systems have largely been replaced by electrical control systems, due to the smaller size and lower cost of electrical components. Pneumatic devices are still used in processes where compressed air is the only energy source available or upgrade cost, safety, and other considerations outweigh the advantage of modern digital control.