From Chemical Engineering point of view it is basically a suspension of solid particles or liquid droplets in gas. Few examples can be smog, haze, smoke etc. The aerosol product consists of the following components: Propellant, Container, Valve and Actuator and Product concentrate.
Propellant: The propellant is generally regarded as the heart of the aerosol package. It is responsible for development of pressure within the container, supplying the necessary force to expel the product when the valve is opened. The propellant also acts as a solvent and as a diluent and has much to do with determining the characteristics of the product as it leaves the container. Examples of propellants include Chloro fluro carbons (CFCs), Hydro fluoro alkanes (HFA)and Fluorinated hydrocarbons
Containers: Different materials are used for the manufacture of aerosol containers. The materials must be inert, non-toxic and must withstand pressure as high as 140 to 180 psig at 130ºF. Examples include aluminum containers, glass etc.
Valves: Valve must be multifunctional in that it is capable of being easily opened and easily closed and capable of delivering the contents in the desired form. Also in case of metered dose inhaler aerosol, the valve is expected to deliver a given amount of medication.
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