Aerosol spray is a type of dispensing system which creates an aerosol mist of liquid particles. This is used with a can or bottle that contains a payload, when the containers valve is opened, the payload is forced out of a small hole and emerges as an aerosol or mist. As propellant expands to drive out the payload, only some propellant evaporates inside the can to maintain a constant pressure, outside the can, the droplets of propellant evaporate rapidly, leaving the payload suspended as very fine particles or droplets. Typical payload liquids dispensed in this way are insecticides, deodorants and paints, an atomizer is a similar device that is pressurised by a hand-operated pump rather than by stored propellant. The concepts of aerosol probably go as far back as 1790, the first aerosol spray can patent was granted in Oslo in 1927 to Erik Rotheim, a Norwegian chemical engineer, and a United States patent was granted for the invention in 1931. The patent rights were sold to a United States company for 100,000 Norwegian kroner, the Norwegian Postal Service, Posten Norge, celebrated the invention by issuing a stamp in 1998. In 1939, American Julian S. Kahn received a patent for a spray can. Kahns idea was to mix cream and a propellant from two sources to make whipped cream at home — not a true aerosol in that sense, moreover, in 1949, he disclaimed his first four claims, which were the foundation of his following patent claims. It was not until 1941 that the spray can was first put to good use by Americans Lyle Goodhue and William Sullivan. Their design of a spray can dubbed the bug bomb, is the ancestor of many popular commercial spray products. In 1948, three companies were granted licenses by the United States government to manufacture aerosols, two of the three companies, Chase Products Company and Claire Manufacturing, still manufacture aerosols to this day. The crimp-on valve, used to control the spray in low-pressure aerosols was developed in 1949 by Bronx machine shop proprietor Robert H. Abplanalp. In 1974, Drs. Frank Sherwood Rowland and Mario J. Molina proposed that chlorofluorocarbons, used as propellants in aerosol sprays, contributed to the depletion of Earths ozone layer. In response to this theory, the U. S. Congress passed amendments to the Clean Air Act in 1977 authorizing the Environmental Protection Agency to regulate the presence of CFCs in the atmosphere. The United Nations Environment Programme called for ozone layer research that same year, in 1985, Joe Farman, Brian G. Gardiner, and Jon Shanklin published the first scientific paper detailing the hole in the ozone layer. That same year, the Vienna Convention was signed in response to the UNs authorization, two years later, the Montreal Protocol, which regulated the production of CFCs was formally signed. It came into effect in 1989, the U. S. formally phased out CFCs in 1995. Usually the gas is the vapor of a liquid with boiling point slightly lower than room temperature and this means that inside the pressurized can, the vapor can exist in equilibrium with its bulk liquid at a pressure that is higher than atmospheric pressure, but not dangerously high
Aerosol spray can
The aerosol (A gaseous suspension of fine solid or liquid particles) spray canister invented by USDA researchers, Lyle Goodhue and William Sullivan.
Image: Canned air
A typical paint valve system will have a "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.