![0-4-0-engine](https://upload.wikimedia.org/wikipedia/commons/3/3f/0-4-0-engine.JPG)
Pneumatics (from Greek ‘wind, breath’) is a branch of
engineering
Engineering is the use of scientific method, scientific principles to design and build machines, structures, and other items, including bridges, tunnels, roads, vehicles, and buildings. The discipline of engineering encompasses a broad rang ...
that makes use of gas or
pressurized air
Compressed air is air kept under a pressure that is greater than atmospheric pressure. Compressed air is an important medium for transfer of energy in industrial processes, and is used for power tools such as air hammers, drills, wrenches, and ...
.
Pneumatic systems used in
industry
Industry may refer to:
Economics
* Industry (economics), a generally categorized branch of economic activity
* Industry (manufacturing), a specific branch of economic activity, typically in factories with machinery
* The wider industrial sector ...
are commonly powered by
compressed air
Compressed air is air kept under a pressure that is greater than atmospheric pressure. Compressed air is an important medium for transfer of energy in industrial processes, and is used for power tools such as air hammers, drills, wrenches, and o ...
or compressed
inert gases
An inert gas is a gas that does not readily undergo chemical reactions with other chemical substances and therefore does not readily form chemical compounds. The noble gases often do not react with many substances and were historically referred to ...
. A centrally located and electrically-powered
compressor
A compressor is a mechanical device that increases the pressure of a gas by reducing its volume. An air compressor is a specific type of gas compressor.
Compressors are similar to pumps: both increase the pressure on a fluid and both can transp ...
powers
cylinders,
air motor
A pneumatic motor (air 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 energy to mechanical work through either linear or rotary ...
s,
pneumatic actuator
A pneumatic control valve actuator converts energy (typically in the form of compressed air) into mechanical motion. The motion can be rotary or linear, depending on the type of actuator.
Principle of operation
A Pneumatic actuator mainly con ...
s, and other
pneumatic
Pneumatics (from Greek ‘wind, breath’) is a branch of engineering that makes use of gas or pressurized air.
Pneumatic systems used in Industrial sector, industry are commonly powered by compressed air or compressed inert gases. A central ...
devices. A pneumatic system controlled through manual or automatic
solenoid valve
A solenoid valve is an electromechanically operated valve.
Solenoid valves differ in the characteristics of the electric current they use, the strength of the magnetic field they generate, the mechanism they use to regulate the fluid, and the ty ...
s is selected when it provides a lower cost, more flexible, or safer alternative to
electric motor
An electric motor is an Electric machine, electrical machine that converts electrical energy into mechanical energy. Most electric motors operate through the interaction between the motor's magnetic field and electric current in a Electromagneti ...
s, and
hydraulic actuator
A hydraulic cylinder (also called a linear hydraulic motor) is a mechanical actuator that is used to give a unidirectional force through a unidirectional stroke. It has many applications, notably in construction equipment (engineering vehicles ...
s.
Pneumatics also has applications in
dentistry
Dentistry, also known as dental medicine and oral medicine, is the branch of medicine focused on the teeth, gums, and mouth. It consists of the study, diagnosis, prevention, management, and treatment of diseases, disorders, and conditions o ...
,
construction
Construction is a general term meaning the art and science to form objects, systems, or organizations,"Construction" def. 1.a. 1.b. and 1.c. ''Oxford English Dictionary'' Second Edition on CD-ROM (v. 4.0) Oxford University Press 2009 and com ...
,
mining
Mining is the extraction of valuable minerals or other geological materials from the Earth, usually from an ore body, lode, vein, seam, reef, or placer deposit. The exploitation of these deposits for raw material is based on the economic via ...
, and other areas.
Gases used in pneumatic systems
![A solenoid actuated pneumatic butterfly valve](https://upload.wikimedia.org/wikipedia/commons/6/62/A_solenoid_actuated_pneumatic_butterfly_valve.jpg)
Pneumatic systems in fixed installations, such as factories, use compressed air because a sustainable supply can be made by compressing
atmospheric air
The atmosphere of Earth is the layer of gases, known collectively as air, retained by Gravity of Earth, Earth's gravity that surrounds the planet and forms its planetary atmosphere. The atmosphere of Earth protects life on Earth by creating Atmo ...
. The air usually has moisture removed, and a small quantity of oil is added at the compressor to prevent corrosion and lubricate mechanical components.
Factory-plumbed pneumatic-power users need not worry about poisonous leakage, as the gas is usually just air. Any compressed gas other than air is an asphyxiation hazard—including nitrogen, which makes up 78% of air. Compressed
oxygen
Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as wel ...
(approx. 21% of air) would not asphyxiate, but is not used in pneumatically-powered devices because it is a fire hazard, more expensive, and offers no performance advantage over air. Smaller or stand-alone systems can use other compressed gases that present an asphyxiation 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 Wars machines and other hobbyist applications are often powered by compressed
carbon dioxide
Carbon dioxide (chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is transpar ...
, because containers designed to hold it such as
soda stream canisters and fire extinguishers are readily available, and the
phase change
In chemistry, thermodynamics, and other related fields, a phase transition (or phase change) is the physical process of transition between one state of a medium and another. Commonly the term is used to refer to changes among the basic State of ...
between liquid and gas makes it possible to obtain a larger volume of compressed gas from a lighter container than compressed air requires. Carbon dioxide is an asphyxiant and can be a freezing hazard if vented improperly.
History
The origins of pneumatics can be traced back to the first century when ancient Greek mathematician
Hero of Alexandria
Hero of Alexandria (; grc-gre, Ἥρων ὁ Ἀλεξανδρεύς, ''Heron ho Alexandreus'', also known as Heron of Alexandria ; 60 AD) was a Greece, Greek mathematician and engineer who was active in his native city of Alexandria, Roman Egy ...
wrote about his inventions powered by steam or the wind.
German physicist
Otto von Guericke
Otto von Guericke ( , , ; spelled Gericke until 1666; November 20, 1602 – May 11, 1686 ; November 30, 1602 – May 21, 1686 ) was a German scientist, inventor, and politician. His pioneering scientific work, the development of experimental me ...
(1602 to 1686) further developed the idea. He invented the vacuum pump, a device that can draw out air or gas from the attached vessel. He demonstrated the vacuum pump to separate the pairs of copper hemispheres using air pressures. The field of pneumatics has changed considerably over the years. It has moved from small handheld devices to large machines with multiple parts that serve different functions.
Comparison to hydraulics
Both pneumatics and
hydraulics
Hydraulics (from Greek: Υδραυλική) is a technology and applied science using engineering, chemistry, and other sciences involving the mechanical properties and use of liquids. At a very basic level, hydraulics is the liquid counter ...
are applications of
fluid 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. Compressed- ...
. Pneumatics uses an easily compressible gas such as air or a suitable pure gas—while hydraulics uses relatively incompressible liquid media such as oil. Most industrial pneumatic applications use pressures of about . Hydraulics applications commonly use from , but specialized applications may exceed .
Advantages of pneumatics
*''Simplicity of design and control''—Machines are easily designed using standard cylinders and other components, and operate via simple on-off control.
*''Reliability''—Pneumatic systems generally have long operating lives and require little maintenance. Because gas is compressible, equipment is less subject to shock damage. Gas absorbs excessive force, whereas fluid in hydraulics directly transfers force. Compressed gas can be stored, so machines still run for a while if electrical power is lost.
*''Safety''—There is a very low chance of fire compared to hydraulic oil. New machines are usually overload safe to a certain limit.
Advantages of hydraulics
* Fluid does not absorb any of the supplied energy.
* Capable of moving much higher loads and providing much lower forces due to the incompressibility.
* The hydraulic working fluid is practically compressible, leading to a minimum of
spring
Spring(s) may refer to:
Common uses
* Spring (season), a season of the year
* Spring (device), a mechanical device that stores energy
* Spring (hydrology), a natural source of water
* Spring (mathematics), a geometric surface in the shape of a ...
action. When
hydraulic fluid
A hydraulic fluid or hydraulic liquid is the medium by which power is transferred in hydraulic machinery. Common hydraulic fluids are based on mineral oil or water. Examples of equipment that might use hydraulic fluids are excavators and backhoe ...
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.
* Highly responsive compared to pneumatics.
* Supply more power than pneumatics.
* Can also do many purposes at one time: lubrication, cooling and power transmission.
Pneumatic logic
Pneumatic logic systems (sometimes called air logic control) are sometimes used for controlling industrial processes, consisting of primary logic units like:
*
And
or AND may refer to:
Logic, grammar, and computing
* Conjunction (grammar), connecting two words, phrases, or clauses
* Logical conjunction in mathematical logic, notated as "∧", "⋅", "&", or simple juxtaposition
* Bitwise AND, a boolea ...
units
*
Or units
*Relay or booster units
*Latching units
*Timer units
*
Fluidics
Fluidics, or fluidic logic, is the use of a fluid to perform analog signal, analog or Digital data, digital operations similar to those performed with electronics.
The physical basis of fluidics is pneumatics and hydraulics, based on the theoret ...
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 electronic control systems in new installations because of the smaller size, lower cost, greater precision, and more powerful features of digital controls. Pneumatic devices are still used where upgrade cost, or safety factors dominate.
Examples of pneumatic systems and components
*
Air brakes on
bus
A bus (contracted from omnibus, with variants multibus, motorbus, autobus, etc.) is a road vehicle that carries significantly more passengers than an average car or van. It is most commonly used in public transport, but is also in use for cha ...
es and
truck
A truck or lorry is a motor vehicle designed to transport cargo, carry specialized payloads, or perform other utilitarian work. Trucks vary greatly in size, power, and configuration, but the vast majority feature body-on-frame construction ...
s
*
Air brakes on
train
In rail transport, a train (from Old French , from Latin , "to pull, to draw") is a series of connected vehicles that run along a railway track and Passenger train, transport people or Rail freight transport, freight. Trains are typically pul ...
s
*
Air compressors
An air compressor is a pneumatic device that converts power (using an electric motor, diesel or gasoline engine, etc.) into potential energy stored in pressurized air (i.e., compressed air). By one of several methods, an air compressor forces ...
*
Air engine
A pneumatic motor (air 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 energy to mechanical work through either linear or rotary m ...
s for pneumatically powered vehicles
*
Barostat
A barostat is a device used to maintain constant pressure in a closed chamber. Its main principle is providing constant pressures in a balloon by means of a pneumatic pump. Barostats are frequently used in neurogastroenterology research, wher ...
systems used in
neurogastroenterology
The enteric nervous system (ENS) or intrinsic nervous system is one of the main divisions of the autonomic nervous system (ANS) and consists of a mesh-like system of neurons that governs the function of the gastrointestinal tract. It is capable ...
and for researching electricity
*
Cable jetting Cable 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
Traditionally, fibre optic cables were pulled throug ...
, a way to install cables in ducts
*
Dental drill
A dental drill or handpiece is a hand-held, mechanical instrument used to perform a variety of common dental procedures, including removing decay, polishing fillings, performing cosmetic dentistry, and altering prostheses.
The handpiece itsel ...
*
Compressed-air engine
A pneumatic motor (air 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 energy to mechanical work through either linear or rotary ...
and
compressed-air vehicle
A compressed-air vehicle (CAV) is a transport mechanism fueled by tanks of pressurized atmospheric gas and propelled by the release and expansion of the gas within a pneumatic motor.
CAV's have found application in torpedoes, locomotives used ...
s
*
Gas Chromatography
Gas chromatography (GC) is a common type of chromatography used in analytical chemistry for separating and analyzing compounds that can be vaporized without decomposition. Typical uses of GC include testing the purity of a particular substance, ...
*
Gas-operated reloading
Gas-operation is a system of operation used to provide energy to operate locked breech, autoloading firearms. In gas-operation, a portion of high-pressure gas from the cartridge being fired is used to power a mechanism to dispose of the spent ...
*
Holman Projector
The 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 ...
, a pneumatic anti-aircraft weapon
*
HVAC control system
HVAC (Heating, Ventilation and Air Conditioning) equipment needs a control system to regulate the operation of a heating and/or air conditioning system. Usually a sensing device is used to compare the actual state (e.g. temperature) with a target ...
s
*
Inflatable structure
An inflatable is an object that can be inflated with a gas, usually with air, but hydrogen, helium and nitrogen are also used. One of several advantages of an inflatable is that it can be stored in a small space when not inflated, since inflata ...
s
*
Lego pneumatics
Lego pneumatics is a variety of Lego bricks which use air pressure and specialised components to perform various actions using the principles of pneumatics.
History
The LEGO pneumatics components were first introduced as part of the LEGO Tech ...
can be used to build pneumatic models
*
Pipe organ
The pipe organ is a musical instrument that produces sound by driving pressurized air (called ''wind'') through the organ pipes selected from a keyboard. Because each pipe produces a single pitch, the pipes are provided in sets called ''ranks ...
**
Electro-pneumatic action
The electro-pneumatic action is a control system by the mean of air pressure 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 ...
**
Tubular-pneumatic action "Tubular-pneumatic action" refers to an apparatus used in many
pipe 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 ...
*
Player piano
A player piano (also known as a pianola) is a self-playing piano containing a pneumatic or electro-mechanical mechanism, that operates the piano action via programmed music recorded on perforated paper or metallic rolls, with more modern i ...
*
Pneumatic actuator
A pneumatic control valve actuator converts energy (typically in the form of compressed air) into mechanical motion. The motion can be rotary or linear, depending on the type of actuator.
Principle of operation
A Pneumatic actuator mainly con ...
*
Pneumatic air guns
*
Pneumatic bladder
A pneumatic bladder is an inflatable (pneumatic) bag technology with many applications.
Emergency management applications
Pneumatic bladders are used to seal drains and ducts to contain chemical spills or gases. Pneumatic bladders are often used f ...
*
Pneumatic cylinder
Pneumatic cylinders (sometimes known as air cylinders) are mechanical devices which use the power of compressed gas to produce a force in a reciprocating linear motion.
Like hydraulic cylinders, something forces a piston to move in the desire ...
*
Pneumatic launchers, a type of spud gun
*
Pneumatic mail systems
*
Pneumatic motor
A pneumatic motor (air 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 energy to mechanical work through either linear or rotary m ...
*
Pneumatic tire
A tire (American English) or tyre (British English) is a ring-shaped component that surrounds a wheel's rim to transfer a vehicle's load from the axle through the wheel to the ground and to provide traction on the surface over which ...
*
Pneumatic tool
A pneumatic tool, air tool, air-powered tool or pneumatic-powered tool is a type of power tool, driven by compressed air supplied by an air compressor. Pneumatic tools can also be driven by compressed carbon dioxide () stored in small cylinders al ...
s:
**
Jackhammer
A jackhammer (pneumatic drill or demolition hammer in British English) is a pneumatic or electro-mechanical tool that combines a hammer directly with a chisel. It was invented by William Mcreavy, who then sold the patent to Charles Brady Kin ...
used by road workers
**
Pneumatic nailgun
*
Pressure regulator
A pressure regulator is a valve that controls the pressure of a fluid or gas to a desired value, using negative feedback from the controlled pressure. Regulators are used for gases and liquids, and can be an integral device with a pressure setti ...
*
Pressure sensor
A pressure sensor is a device for pressure measurement 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 act ...
*
Pressure switch
A pressure switch is a form of switch that operates an electrical contact when a certain set fluid pressure has been reached on its input. The switch may be designed to make contact either on pressure rise or on pressure fall. Pressure switches ar ...
*
Launched roller coaster
The launched roller coaster is a modern form of roller coaster. A launched coaster initiates a ride with high amounts of acceleration via one or a series of linear induction motors (LIM), linear synchronous motors (LSM), catapults, tires, chains ...
*
Vacuum pump
A vacuum pump is a device that draws gas molecules from a sealed volume in order to leave behind a partial vacuum. The job of a vacuum pump is to generate a relative vacuum within a capacity. The first vacuum pump was invented in 1650 by Otto v ...
*
Vacuum sewer
A vacuum sewer or pneumatic sewer system is a method of transporting sewage from its source to a sewage treatment plant. It maintains a partial vacuum, with an air pressure below atmospheric pressure inside the pipe network and vacuum station ...
See also
*
Compressed air
Compressed air is air kept under a pressure that is greater than atmospheric pressure. Compressed air is an important medium for transfer of energy in industrial processes, and is used for power tools such as air hammers, drills, wrenches, and o ...
*
Ozone cracking
Cracks can be formed in many different elastomers by ozone attack, and the characteristic form of attack of vulnerable rubbers is known as ozone cracking. The problem was formerly very common, especially in tires, but is now rarely seen in those ...
- can affect pneumatic seals
*
Pneudraulics
Derived from the words hydraulics and pneumatics, pneudraulics is the term used when discussing systems on military aircraft that use either or some combination of hydraulic and pneumatic systems.
The science of fluids made of both gas and liqu ...
*
History of pneumatic power
Notes
References
* Brian S. Elliott, ''Compressed Air Operations Manual'', McGraw Hill Book Company, 2006, .
* Heeresh Mistry, ''Fundamentals of Pneumatic Engineering'', Create Space e-Publication, 2013, .
External links
Four Ways to Boost Pneumatic Efficiency
{{Authority control