Aerosol spray 583877 220972692 2008-06-22T13:40:38Z 87.194.27.249 /* Packaging */ Removed blatant advertising {{refimprove|article|date=April 2008}} [[Image:Aerosol.png|thumb|right|250px|Aerosol spray can]] [[Image:canned-air.jpg|thumb|250px|right|Canned-Air / Spray Dusters are dangerous to inhale. They do not use compressed air, but rather other inert gasses.]] '''Aerosol spray''' is a type of dispensing system which creates an [[Particulate|aerosol]] mist of liquid particles. This is used with a [[spray can|can]] or [[bottle]] that contains a liquid under pressure. When the container's valve is opened, the liquid is forced out of a small hole and emerges as an [[Particulate|aerosol]] or [[mist]]. As gas expands to drive out the payload, some propellant evaporates inside the can to maintain an even pressure. Outside the can, the droplets of propellant evaporate rapidly, leaving the payload suspended as very fine particles or droplets. Typical liquids dispensed in this way are [[insecticide]]s, [[deodorant]]s and [[aerosol paint|paint]]s. An [[atomization|atomiser]] is a similar device that is pressurised by a hand-operated pump rather than by stored gas. == History == The concepts of aerosol probably dates back to 1790.<ref name= Bellis> Bellis, Mary [http://inventors.about.com/od/astartinventions/a/aerosol.htm The History of Aerosol Spray Cans]</ref> The first aerosol spray can was invented in [[Oslo]] in 1926 by Erik Rotheim, a [[Norway|Norwegian]] chemical engineer.<ref name= Bellis/> The patent was sold to a US company for 100,000 [[Norwegian krone]]rs.{{Fact|date=April 2007}} The Norwegian Post Office celebrated the invention by issuing a stamp with the aerosol spray can on it in 1998.<ref>[http://cache.aftenposten.no/multimedia/archive/00101/FRIMERKE_101049a.jpg Image of the Norway Postage stamp]</ref> [[Image:Aerosol 1943.jpg|thumb|left|The aerosol spray canister invented by [[USDA]] researchers, Lyle Goodloe and William Sullivan.]] In 1941 the aerosol spray can was first put to good use by [[USA|Americans]] Lyle Goodloe and William Sullivan, who are credited as the inventors of the modern spray can.<ref name=McGrath>{{cite book |author=Kimberley A. McGrath (Editor), Bridget E. Travers (Editor) |title=World of Invention "Summary"| url= http://www.bookrags.com/research/aerosol-spray-woi/ |publisher=Thomson Gale |location=Detroit|year= |pages= |isbn=0-7876-2759-3 |oclc= |doi=}}</ref> Their design of a refillable spray can (dubbed the “bug bomb”) patented in 1943 is the ancestor of many spray products. Pressurized by liquefied gas, the small portable can enabled soldiers to defend against [[malaria]]-carrying bugs by spraying inside [[tents]] in the [[Pacific]] during [[World War II]].<ref>Core, Jim, Rosalie Marion Bliss, and Alfredo Flores. (September 2005) [http://ars.usda.gov/is/ar/archive/sep05/vector0905.htm?pf=1 "ARS Partners With Defense Department To Protect Troops From Insect Vectors"]. ''Agricultural Research Magazine''Vol. 53, No. 9 .</ref> In 1948, three companies were granted licenses by the United States government to manufacture aerosols. Two of the three companies still manufacture aerosols to this day, Chase Products Company and Claire Manufacturing. The "crimp-on valve", used to control the spray was developed in 1949 by [[Bronx]] machine shop proprietor [[Robert Abplanalp|Robert H. Abplanalp]].<ref name=McGrath/> <br /> == Technology (aerosol propellants) == If the can were simply filled with compressed gas, either it would need to be at a dangerously high pressure, or the amount of gas in the can would be small, and would rapidly deplete. Usually the gas is the [[vapour]] of a liquid with [[boiling point]] slightly lower than [[room temperature]]. This means that inside the pressurised can, the vapour can exist in [[thermodynamic equilibrium|equilibrium]] with its bulk liquid at a pressure that is higher than [[atmospheric pressure]] (and able to expel the payload), but not dangerously high. As gas escapes, it is immediately replaced by evaporating liquid. Since the propellant exists in liquid form in the can, it should be miscible with the payload or dissolved in the payload. [[Chlorofluorocarbon]]s (CFCs) were once often used, but since the [[Montreal Protocol]] came into force in 1989, they have been replaced in nearly every country due to the negative effects CFCs have on Earth's [[ozone layer]]. The most common replacements are mixtures of volatile [[hydrocarbon]]s, typically [[propane]], n-[[butane]] and [[isobutane]]. [[Dimethyl ether]] (DME) and [[methyl ethyl ether]] are also used. All these have the disadvantage of being flammable. [[Nitrous oxide]] and [[carbon dioxide]] are also used as propellants to deliver foodstuffs (for example, whipped [[cream (food)|cream]] and [[cooking spray]]). Medicinal aerosols such as [[asthma inhaler]]s use hydrofluoroalkanes (HFA): either HFA 134a (1,1,1,2,-tetrafluoroethane) or HFA 227 (1,1,1,2,3,3,3-heptafluoropropane) or combinations of the two. ==Packaging== [[Image:Aerosol tops 6.svg|thumb|223px|A typical paint valve system will have a "[[Gender of connectors and fasteners|female]]" valve, the stem being part of the top actuator. The valve can be preassembled with the valve cup and installed on the can as one piece, prior to pressure-filling. The actuator is added later.]] Modern aerosol spray products have three major parts; the can, the valve and the actuator or button. The can is most commonly lacquered [[tinplate]] (steel with a layer of tin) and may be made of 2 or 3 pieces of metal crimped together. [[Aluminium]] cans are also common and are generally used for more expensive products. The valve is crimped to the rig of the can, the design of this component is important in determining the spray rate. The actuator is depressed by the user to open the valve; the shape and size of the nozzle in the actuator controls the spread of the aerosol spray. Packaging that uses a piston barrier system is often used for highly viscous products such as post-foaming hair gels, thick creams and lotions, food spreads and industrial products and sealants. The main benefit of the piston barrier system is that is assures separation of the product from the propellant, maintaining the purity and integrity of the formulation throughout its consumer lifespan. The piston barrier system also provides a controlled and uniform product discharge rate with minimal product retention and is economical. Another type of dispensing system is the bag-in-can system (or BOV “bag on valve”). This system separates the product from the pressurizing agent with a hermetically-sealed, multi-layered laminated pouch, which maintains complete formulation integrity so only pure product is dispensed. Among its many benefits, the bag-in-can system extends a product’s shelf life. The bag-on-valve, or ABS, is widely used by sun care marketers for its benefits: all-attitude (360-degree) dispensing, quiet and non-chilling discharge. This bag-in-can system is also used in the packaging of pharmaceutical, industrial, household, pet care and other products that require complete separation between the product and the propellant. ==Health concerns== There are two main areas of health concern linked to aerosol cans: * Deliberate [[inhalant|inhalation]] of the contents to gain a high from the propellant * The piggy-backing of more dangerous particles into the respiratory tracts == See also == {{Commons|Category:Spray cans|Aerosol spray}} * [[Aerosol paint]] * [[Air pollution]] * [[Haloalkane|Freon]] * [[Ozone depletion]] * [[Nitrous oxide]] * [[Packaging]] ==References== <references/> ==Further reading== * Brody, A. L., and Marsh, K, S., "Encyclopedia of Packaging Technology", John Wiley & Sons, 1997, ISBN 0-471-06397-5 * [[ASTM]] D3069 Delivery Rate of Aerosol Products * [[ASTM]] D3065 Flammability of Aerosol Products * [[ASTM]] D3094 Seepage Rate of Aerosol Products [[Category:Containers]] [[Category:Norwegian inventions]] [[da:Spraydåse]] [[de:Sprühdose]] [[es:Pulverizador]] [[eo:Sprajilo]] [[fr:Spray aérosol]] [[it:Bomboletta spray]] [[nl:Spuitbus]] [[ja:スプレー]] [[ru:Аэрозольный баллон]] [[simple:Aerosol spray]] [[fi:Suihkepullo]] [[sv:Sprayburk]]