aerosol dispenser,device designed to produce a fine spray of liquid or solid particles that can be suspended in a gas such as the atmosphere. The dispenser commonly consists of a container that holds under pressure the substance to be dispersed (e.g., paints, insecticides, medications, and hair sprays) and a liquefied gas propellant. When a valve is released, the propellant forces the substance through an atomizer and out of the dispenser in the form of a fine spray. These devices are more properly termed spray dispensers rather than aerosol dispensers because the particles of the dispersed substance are usually larger than the particles of a true aerosol (see colloidcolloid
[Gr.,=gluelike], a mixture in which one substance is divided into minute particles (called colloidal particles) and dispersed throughout a second substance. The mixture is also called a colloidal system, colloidal solution, or colloidal dispersion.
..... Click the link for more information. ), such as a fog or a smoke. FreonFreon
[trade name], any one of a special class of chemical compounds that are used as refrigerants, aerosol propellants, and solvents. These compounds are haloalkanes, i.e., halogen derivatives of saturated hydrocarbons (see alkane).
..... Click the link for more information. was the most common aerosol propellant, but its use has been banned because it is believed to contribute to destruction of the ozone layerozone layer
region of the stratosphere containing relatively high concentrations of ozone, located at altitudes of 12–30 mi (19–48 km) above the earth's surface.
..... Click the link for more information. of the stratospherestratosphere
, second lowest layer of the earth's atmosphere. The level from which it extends outward varies with latitude; it begins c.5 1-2 mi (9 km) above the poles, c.6 or 7 mi (c.10 or 11 km) in the middle latitudes, and c.10 mi (16 km) at the equator, and extends outward c.
..... Click the link for more information. ; common propellants now include propane, butane, and other hydrocarbons.