Pneumatics


Pneumatics
Preserved Porter Locomotive Company No. 3290 of 1923.

Pneumatics is a branch of technology, which deals with the study and application of use of pressurized gas to effect mechanical motion.

Pneumatic systems are extensively used in industry, where factories are commonly plumbed with compressed air or compressed inert gases. This is because a centrally located and electrically powered compressor that powers cylinders and other pneumatic devices through solenoid valves is often able to provide motive power in a cheaper, safer, more flexible, and more reliable way than a large number of electric motors and actuators.

Pneumatics also has applications in dentistry, construction, mining, and other areas.

Contents

Examples of pneumatic systems and components

Pneumatic circuit.

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 - 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 (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 machines and other hobbyist applications are often powered by compressed carbon dioxide 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 power. 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 80 to 100 pounds per square inch (550 to 690 kPa). Hydraulics applications commonly use from 1,000 to 5,000 psi (6.9 to 34 MPa), but specialized applications may exceed 10,000 psi (69 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 spring 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:

  • And Units
  • Or Units
  • 'Relay or Booster' Units
  • Latching Units
  • 'Timer' Units
  • Sorteberg relay
  • fluidics 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.

See also

References

External links


Wikimedia Foundation. 2010.

Synonyms:

Look at other dictionaries:

  • Pneumatics — Pneu*mat ics, n. [Cf. F. pneumatique.] [1913 Webster] 1. That branch of science which treats of the mechanical properties of air and other elastic fluids, as of their weight, pressure, elasticity, etc. See {Mechanics}. [1913 Webster] 2. (Philos.… …   The Collaborative International Dictionary of English

  • pneumatics — 1650s, from PNEUMATIC (Cf. pneumatic). Also see ICS (Cf. ics) …   Etymology dictionary

  • pneumatics — [no͞o mat′iks, nyo͞o mat′iks] n. the branch of physics that deals with the mechanical properties of air and other gases …   English World dictionary

  • pneumatics — Mechanics Me*chan ics, n. [Cf. F. m[ e]canique.] That science, or branch of applied mathematics, which treats of the action of forces on bodies. [1913 Webster] Note: That part of mechanics which considers the action of forces in producing rest or …   The Collaborative International Dictionary of English

  • pneumatics — pneumatika statusas T sritis automatika atitikmenys: angl. pneumatics vok. Pneumatik, f rus. пневматика, f pranc. pneumatique, f …   Automatikos terminų žodynas

  • pneumatics — pneumatika statusas T sritis fizika atitikmenys: angl. pneumatics vok. Pneumatik, f rus. пневматика, f pranc. pneumatique, f …   Fizikos terminų žodynas

  • pneumatics — /noo mat iks, nyoo /, n. (used with a sing. v.) the branch of physics that deals with the mechanical properties of air and other gases. Also called pneumodynamics. [1650 60; see PNEUMATIC, ICS] * * * …   Universalium

  • pneumatics — noun The branch of mechanics that deals with the mechanical properties of gases See Also: pneumatic …   Wiktionary

  • pneumatics — The science concerned with the physical properties of air or gases. [G. pneuma, air or gas] * * * pneu·mat·ics n(y)u̇ mat iks n pl but sing in constr a branch of mechanics that deals with the mechanical properties of gases * * * pneu·mat·ics (noo …   Medical dictionary

  • pneumatics — Synonyms and related words: aerial photography, aeroballistics, aerodynamics, aerogeology, aerography, aerology, aeromechanics, aeromedicine, aerometry, aeronautical meteorology, aerophotography, aerophysics, aeroscopy, aerospace research,… …   Moby Thesaurus


Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.