|
|
| Line 1: |
Line 1: |
| '''Outgassing''' (sometimes called '''offgassing''', particularly when in reference to [[indoor air quality]]) is the release of a [[gas]] that was dissolved, trapped, [[freezing|frozen]] or [[Absorption (chemistry)|absorbed]] in some material.<ref>{{cite book | first=John | last=Strong | date=1938 | title=[[Procedures in Experimental Physics]] | publisher=Lindsay Publications | location=Bradley, IL | id= }}, Chapter 3</ref> Outgassing can include [[sublimation (chemistry)|sublimation]] and [[evaporation]] which are [[phase transition]]s of a substance into a gas, as well as [[desorption]], seepage from cracks or internal volumes and gaseous products of slow [[chemical reaction]]s. [[Boiling]] is generally thought of as a separate phenomenon from outgassing because it consists of a phase transition of a liquid into a vapor made of the same substance. | | '''Offgassing''' or '''outgassing''' is the release of a [[gas]] that was dissolved, trapped, [[freezing|frozen]] or [[Absorption|absorbed]] in some material.<ref>{{cite book | first=John | last=Strong | date=1938 | title=[[Procedures in Experimental Physics]] | publisher=Lindsay Publications | location=Bradley, IL | id= }}, Chapter 3</ref> Offgassing can include [[phase transition]]s of a substance into a gas ([[sublimation]] and [[evaporation]]), as well as [[desorption]], seepage from cracks or internal volumes and gaseous products of slow [[chemical reaction]]s. [[Boiling]] is generally thought of as a separate phenomenon from offgassing because it consists of a phase transition of a liquid into a vapor made of the same substance. |
|
| |
|
| == In a vacuum == | | == In a closed environment == |
|
| |
|
| Outgassing is a challenge to creating and maintaining clean high-[[vacuum]] environments. [[NASA]] and [[ESA]] maintains a list of low-outgassing materials to be used for spacecraft, as outgassing products can condense onto optical elements, [[thermal radiator]]s, or [[solar cell]]s and obscure them. Materials not normally considered absorbent can release enough light-weight [[molecule]]s to interfere with industrial or scientific vacuum processes. [[Moisture]], [[sealant]]s, [[lubricant]]s, and [[adhesive]]s are the most common sources, but even [[metal]]s and [[glass]]es can release gases from cracks or impurities. The rate of outgassing increases at higher [[temperature]]s because the [[vapour pressure]] and rate of chemical reaction increases. For most solid materials, the method of manufacture and preparation can reduce the level of outgassing significantly. Cleaning surfaces or baking individual components or the entire assembly before use can drive off volatiles.
| | Offgassing can be significant if it collects in a closed environment where air is stagnant or recirculated. For example, "new car smell" consists of offgassed chemicals released by heat in a closed automobile. Even a nearly odourless material such as wood may build up a strong smell if kept in a closed box for months. There is some concern that [[plasticizer]]s and [[solvent]]s released from many industrial products, especially plastics, may be harmful to human health.<ref name="Health Concerns">{{cite web|title=Health Concerns|url=http://www.epa.gov/dfe/pubs/projects/spf/health_concerns_associated_with_chemicals_in_spray_polyurethane_foam_products.html|publisher=United States Environmental Protection Agency|accessdate=10 June 2013}}</ref> Some types of [[Vulcanization|RTV]] sealants offgas the poison [[cyanide]] for weeks after application.{{fact}} Offgassing toxic gases are of particular concern in the design of submarines and space stations, which must have self-contained recirculated atmospheres. |
|
| |
|
| NASA's [[Stardust (spacecraft)|Stardust]] spaceprobe suffered [http://stardust.jpl.nasa.gov/news/vision.html reduced image quality] due to an unknown contaminant that had condensed on the [[Charge-coupled device|CCD]] sensor of the navigation camera. A similar problem affected the [[Cassini–Huygens|Cassini]] spaceprobe's [http://saturn.jpl.nasa.gov/news/press-releases-02/20020723-pr-a.cfm Narrow Angle Camera],{{dead link|date=August 2016}} but was corrected by repeatedly heating the system to 4 [[Celsius|°C]]. A comprehensive characterisation of outgassing effects using mass spectrometers could be obtained for ESA's [[Rosetta (spacecraft)|Rosetta]] spacecraft.<ref>B. Schläppi, et al. (2010), Influence of spacecraft outgassing on the exploration of tenuous atmospheres with in situ mass spectrometry, J. Geophys. Res., 115, A12313, {{doi|10.1029/2010JA015734}}.</ref>
| | == In construction == |
| | |
| | The offgassing of small pockets of air near the surface of setting [[concrete]] can lead to permanent holes in the structure (called "bugholes") that may compromise its structural integrity.<ref name=crb>{{citation |url=https://www.icri.org/PUBLICATIONS/2008/PDFs/janfeb08/CRBJanFeb08_ODea.pdf |title=Thin-Patch Repair of Concrete in Wastewater Environments Using Commercially Available Cementitious Resurfacers |publisher=Concrete Repair Bulletin |date=January 2008 |accessdate=2014-10-21}}</ref><ref name=preventing>{{citation |url=http://www.macoatings.com/site/wp-content/uploads/2011/06/Maintenance_Tips_Preventing_Air-Induced_Coating_Failures_on_Concrete.pdf |title=Preventing Air-Induced Coating Failures on Concrete |publisher=JPCL |date=January 2007 |accessdate=2014-10-21}}</ref> |
|
| |
|
| == From rock == | | == From rock == |
|
| |
|
| Outgassing is the source of many tenuous [[Celestial body atmosphere|atmospheres]] of [[terrestrial planets]] or moons. Many materials are volatile relative to the extreme vacuum of space, such as around the [[Moon]], and may evaporate or even boil at ambient temperature. Materials on the [[lunar surface]] have completely outgassed and been ripped away by [[solar wind]]s long ago, but volatile materials may remain at depth. Once released, gases almost always are less [[Density|dense]] than the surrounding [[Rock (geology)|rocks]] and [[sand]] and seep toward the surface. The [[Atmosphere of the Moon|lunar atmosphere]] probably originates from outgassing of warm material below the surface. At the Earth's [[Divergent boundary|tectonic divergent boundaries]] where new [[Crust (geology)|crust]] is being created, [[helium]] and [[carbon dioxide]] are some of the volatiles being outgassed from [[mantle (geology)|mantle]] [[magma]].
| | At the Earth's [[Divergent boundary|tectonic divergent boundaries]] where new crust is being created, [[helium]] and [[carbon dioxide]] are some of the volatiles being offgassed from mantle magma. |
| | |
| == In a closed environment ==
| |
| | |
| Outgassing can be significant if it collects in a closed environment where air is stagnant or recirculated. For example, [[new car smell]] consists of outgassed chemicals released by heat in a closed automobile. Even a nearly odourless material such as wood may build up a strong smell if kept in a closed box for months. There is some concern that [[plasticizer]]s and [[solvent]]s released from many industrial products, especially plastics, may be harmful to human health.<ref name="Health Concerns">{{cite web|title=Health Concerns|url=http://www.epa.gov/dfe/pubs/projects/spf/health_concerns_associated_with_chemicals_in_spray_polyurethane_foam_products.html|publisher=United States Environmental Protection Agency|accessdate=10 June 2013}}</ref> Some types of [[Vulcanization#Room temperature vulcanization|RTV]] sealants outgas the poison [[cyanide]] for weeks after application.{{Citation needed|reason=this is a strong claim which can't be included here without proper citations.|date=April 2009}} Outgassing toxic gases are of great concern in the design of [[submarine]]s and [[space station]]s, which must have self-contained recirculated atmospheres.
| |
| | |
| == In construction ==
| |
| | |
| The outgassing of small pockets of air near the surface of setting [[concrete]] can lead to permanent holes in the structure (called [[bughole]]s) that may compromise its structural integrity.<ref name=crb>{{citation |url=https://www.icri.org/PUBLICATIONS/2008/PDFs/janfeb08/CRBJanFeb08_ODea.pdf |title=Thin-Patch Repair of Concrete in Wastewater Environments Using Commercially Available Cementitious Resurfacers |publisher=Concrete Repair Bulletin |date=January 2008 |accessdate=2014-10-21}}</ref><ref name=preventing>{{citation |url=http://www.macoatings.com/site/wp-content/uploads/2011/06/Maintenance_Tips_Preventing_Air-Induced_Coating_Failures_on_Concrete.pdf |title=Preventing Air-Induced Coating Failures on Concrete |publisher=JPCL |date=January 2007 |accessdate=2014-10-21}}</ref>
| |
|
| |
|
| == See also == | | == See also == |
| * [[Volatile organic compound]] | | * [[Volatile organic compound]] |
| * [[Lake Nyos#1986 disaster|1986 Lake Nyos Disaster]]
| |
| * [[Materials for use in vacuum]]
| |
|
| |
|
| == References == | | == References == |
| {{reflist}} | | {{reflist}} |
|
| |
|
| == External links ==
| | [[Category:Chemistry]] |
| * [http://outgassing.nasa.gov/ Outgassing Data for Selecting Spacecraft Materials Online (NASA database)]
| | [[Category:Construction]] |
| * [http://esmat.esa.int/Services/outgassing_data/outgassing_data.html ESA Outgassing Data for Spacecraft Materials according to ECSS-Q-70-02]
| | [[Category:Health and safety]] |
|
| |
|
| [[Category:Vacuum]]
| | {{attrib wikipedia|Outgassing}} |
| [[Category:Gas technologies]]
| |
Offgassing or outgassing is the release of a gas that was dissolved, trapped, frozen or absorbed in some material.[1] Offgassing can include phase transitions of a substance into a gas (sublimation and evaporation), as well as desorption, seepage from cracks or internal volumes and gaseous products of slow chemical reactions. Boiling is generally thought of as a separate phenomenon from offgassing because it consists of a phase transition of a liquid into a vapor made of the same substance.
In a closed environment
Offgassing can be significant if it collects in a closed environment where air is stagnant or recirculated. For example, "new car smell" consists of offgassed chemicals released by heat in a closed automobile. Even a nearly odourless material such as wood may build up a strong smell if kept in a closed box for months. There is some concern that plasticizers and solvents released from many industrial products, especially plastics, may be harmful to human health.[2] Some types of RTV sealants offgas the poison cyanide for weeks after application.[verification needed] Offgassing toxic gases are of particular concern in the design of submarines and space stations, which must have self-contained recirculated atmospheres.
In construction
The offgassing of small pockets of air near the surface of setting concrete can lead to permanent holes in the structure (called "bugholes") that may compromise its structural integrity.[3][4]
From rock
At the Earth's tectonic divergent boundaries where new crust is being created, helium and carbon dioxide are some of the volatiles being offgassed from mantle magma.
See also
References
Template:Reflist
Template:Attrib wikipedia
