Outgassing


Outgassing

Outgassing (sometimes called offgassing, particularly when in reference to indoor air quality) is the release of a gas that was dissolved, trapped, frozen or absorbed in some material.[1] As an example, research has shown how the concentration of carbon dioxide in the Earth's atmosphere has sometimes been linked to ocean outgassing. [2] It can include sublimation and evaporation which are phase transitions of a substance into a gas, 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 outgassing because it consists of a phase transition of a liquid into a vapor made of the same substance.

Contents

Outgassing in a vacuum

Outgassing is a challenge to creating and maintaining clean high-vacuum environments. NASA maintains a list of low-outgassing materials to be used for spacecraft, as outgassing products can condense onto optical elements, thermal radiators, or solar cells and obscure them. Materials not normally considered absorbent can release enough light-weight molecules to interfere with industrial or scientific vacuum processes. Moisture, sealants, lubricants, and adhesives are the most common sources, but even metals and glasses can release gases from cracks or impurities. The rate of outgassing increases at higher temperatures 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.

NASA's Stardust spaceprobe suffered reduced image quality due to an unknown contaminant that had condensed on the CCD sensor of the navigation camera. A similar problem affected the Cassini-Huygens spaceprobe's Narrow Angle Camera, but was corrected by repeatedly heating the system to 4 degrees Celsius. A comprehensive characterisation of outgassing effects using mass spectrometers could be obtained for ESA's Rosetta spacecraft.[3]

Outgassing from rock

Outgassing is the source of many tenuous atmospheres of terrestrial planets or moons. Many materials are volatile relative to the extreme vacuum of space, such as around the Earth's Moon, and may evaporate or even boil at ambient temperature. Materials on the lunar surface have completely outgassed and been ripped away by solar winds long ago, but volatile materials may remain at depth. Once released, gases almost always are less dense than the surrounding rocks and sand and seep toward the surface. The lunar atmosphere probably originates from outgassing of warm material below the surface. At the Earth's tectonic divergent boundaries where new crust is being created, helium and carbon dioxide are some of the volatiles being outgassed from mantle magma.

Outgassing in a closed environment

Outgassing can be significant if it collects in a closed environment where air is stagnant or recirculated. This is, for example, the origin of new car smell. 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 softeners and solvents that are released from many industrial products, especially plastics, may be harmful to human health.[citation needed]. Some types of RTV sealants outgas the poison cyanide for weeks after application[citation needed]. These outgassing poisons are of great concern in the design of submarines and space stations.

See also

Note: VOCs don't outgas; they create a significant vapor pressure not because they have absorbed gas, but because they break down (depolymerize) due to time, light, and heat.

External links

Notes

  1. ^ Strong, John (1938). Procedures in Experimental Physics. Bradley, IL: Lindsay Publications. , Chapter 3
  2. ^ http://www.gfdl.noaa.gov/bibliography/related_files/us9301.pdf
  3. ^ 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.

Wikimedia Foundation. 2010.

Look at other dictionaries:

  • outgassing —  Outgassing  Дегазация   Выделение из материалов сорбированных ими газов или паров при нагревании или в вакууме. Также один из видов обеззараживания, представляющий собой уничтожение (нейтрализацию) сильно действующих ядовитых веществ (боевых… …   Толковый англо-русский словарь по нанотехнологии. - М.

  • outgassing — degazavimas statusas T sritis Standartizacija ir metrologija apibrėžtis Dujų pašalinimas. atitikmenys: angl. degassing; outgassing vok. Entgasung, f rus. дегазация, f; дегазирование, n pranc. dégazage, m …   Penkiakalbis aiškinamasis metrologijos terminų žodynas

  • outgassing — degazavimas statusas T sritis chemija apibrėžtis Dujų pašalinimas. atitikmenys: angl. degasification; degassing; outgassing rus. дегазация; дегазификация; обезгаживание …   Chemijos terminų aiškinamasis žodynas

  • outgassing — dujų šalinimas statusas T sritis fizika atitikmenys: angl. degassing; gas clean up; outgassing vok. Entgasung, f rus. дегазация, f; обезгаживание, n pranc. dégazage, m; dégazation, f; dégazéification, f …   Fizikos terminų žodynas

  • outgassing — degazavimas statusas T sritis ekologija ir aplinkotyra apibrėžtis Nuodingų medžiagų neutralizavimas, skaidymas arba šalinimas. atitikmenys: angl. degassing; gas clean–up; outgassing vok. Entgasung, f rus. дегазация, f …   Ekologijos terminų aiškinamasis žodynas

  • outgassing — noun The slow release of gas from a solid or liquid; especially the release of gases into the atmosphere of a planet …   Wiktionary

  • Outgassing —   The process by which materials expel or release gasses …   Energy terms

  • Outgassing —    The process where the gases of a planet s atmosphere come from gases escaping from the planets crust …   The writer's dictionary of science fiction, fantasy, horror and mythology

  • outgassing — outgassˈing noun 1. Loss of, or removal of, occluded or adsorbed gas from a solid under vacuum conditions 2. Also removal of gas from a liquid • • • Main Entry: ↑out …   Useful english dictionary

  • Bughole-induced outgassing — is a phenomenon occurring when applying a protective coating (or lining) to concrete (predominantly vertically cast in place) where air becomes entrapped within bughole cavities and releases into or through the protective coating, thereby causing …   Wikipedia


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.