Gas duster
Gas duster, also known as canned air or compressed air, is a product used for cleaning electronic equipment and other sensitive devices that cannot be cleaned using water. Despite the name "canned air", the cans actually contain gases that are compressable into liquids. Air on the contrary, cannot be compressed into liquid at any pressure since the critical temperatures of air components (-146.9 C for nitrogen; -118.6 C for oxygen) are much beyond normal handling temperatures. Duster gases are such as 1,1-difluoroethane, 1,1,1-trifluoroethane, or 1,1,1,2-tetrafluoroethane. Hydrocarbons, like butane, were often used in the past, but their flammable nature forced manufacturers to use fluorocarbons. When inhaled, gas duster produces powerful psychoactive effects and may be harmful to health.
Safety
Since gas dusters are one of the many inhalants that can be easily abused,[1] many manufacturers have added a bittering agent to deter people from inhaling the product. Because of the generic name "canned air", it was mistakenly believed that the can only contains normal air or contains a less harmful substance such as nitrous oxide. However, the gases actually used are denser than air, such as difluoroethane. When inhaled, the gas displaces the oxygen in the lungs and removes carbon dioxide from the blood causing the user to suffer from hypoxia which results in the euphoric feeling abusers desire. This type of inhalant abuse can cause a plethora of negative effects including brain and nerve damage, paralysis, serious injury, or death.[2]
Though not extremely flammable in gaseous form, many dusters use a fluorocarbon that can burn under some conditions. As such, there is also a warning label present on some gas dusters. When inverted to spray liquid, the boiling fluorocarbon aerosol is easily ignitable, producing a very large blast of flame and extremely toxic byproducts such as hydrogen fluoride and carbonyl fluoride as a combustion product.
Fluorocarbons, although they replaced the older set of more flammable hydrocarbons, can still combust relatively easily, e.g., by holding a source of fire (such as a match or lighter) to the escaping fluid. They do, however, have a lower chance of exploding in a closed container by means of spontaneous combustion.
The liquid, when released from the can, boils at a very low temperature, rapidly cooling any surface it touches.[3] This can cause frostbite on contact with skin. As the can gets very cold during extended use, holding the can itself can result in frostbite.
Since gas dusters are often contained in pressure vessels, they are considered explosively volatile.
Environmental impacts
Global warming: Difluoroethane (HFC-152a), trifluoroethane (HFC-143a), and completely non-flammable tetrafluoroethane (HFC-134a) are potent greenhouse gases. According to the Intergovernmental Panel on Climate Change (IPCC), the global warming potential (GWP) of HFC-152a, HFC-143a, and HFC-134a are 124, 4470, and 1430, respectively.[4] GWP refers to global warming effect in comparison to CO2 for unit mass. 1 kg of HFC-152a is equivalent to 124 kg of CO2[5]
Ozone layer depletion: Gas dusters sold in many countries are ozone safe as they use "zero ODP" (zero ozone depletion potential) gases; tetrafluoroethane, for example, has insignificant ODP. This is a separate issue from the global warming concern.
Off Label Uses
Many gas dusters contain HFC-134a (tetrafluoroethane), which is widely used as a propellant and refrigerant. HFC-134a sold for those purposes is often sold at a much higher unit price, which has led to the practice of using gas dusters as a less expensive source of HFCs for those purposes. Adapters have been built for such purposes, though in most cases, use of such adapters will void the warranty on the equipment they are used with. One example of this practice is the case of airsoft gas guns, which use HFC-134a as the compressed gas. Several vendors sell "duster adapters" for use with airsoft guns, though it is necessary to add a lubricant when using gas dusters to power airsoft guns.
Alternatives
True "air dusters" using ordinary air are also available in the market. These typically have much shorter run times than a chemical duster, but are readily refillable. Both hand pump and electric compressor models have been marketed. The maximum pressure for an aerosol can is typically 10 bar (145 psi) at 20 C.[6] Therefore, a fully compressed air duster will exhaust air about 10 times the can volume.
See also
References
- ↑ http://www.snopes.com/medical/toxins/dustoff.asp
- ↑ http://www.medicinenet.com/script/main/art.asp?articlekey=47975
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- ↑ http://www.chemaxx.com/aerosol12a.htm
