Name: Jo M.
Exactly how does an aerosol can work? I thought the
material was compressed when sealed in the can and as the material is
released from the can it would expand. I have students who think that
the air has been removed from the substance and somehow gets "mixed" with
the substance as it is being released from the can.
The can contains both product and propellant. The propellant is basically a
substance that is a gas at normal atmospheric pressure, but which condenses
to a liquid at moderately higher pressures. When you press down the valve,
some of the propellant turns to gas and carries some of the product out of
the can with it in a fine spray.
Richard E. Barrans Jr., Ph.D.
PG Research Foundation, Darien, Illinois
There is a whole aerosol can technology -- rather sophisticated too. There
are several mechanisms: 1. In some cases the propellant is soluble in the
medium. When the can is activated the propellant expands, ejecting the
medium and foaming it at the same time. This is used in canned whipped cream
(the propellant is NNO which is non-toxic and soluble in the cream. This is
also used in "Edge" shaving cream (here the propellant is a propane/butane
2. Another mechanism requires that the medium and the propellant are
separated by a flexible bladder, with the medium on the top and the
propellant on the bottom. When the can is activated, the propellant just
"pushes" the medium out, but never actually mixes with it. 3. Yet another
mechanism works on the principle of a Venturi pump in which the propellant
sucks up the medium and they pass through a nozzle that atomizes the medium.
Household insecticides often use this design. Of course the design of the
nozzle becomes a whole technology depending upon the desired droplet size
These are only three examples of a rather complicated delivery technology.
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Update: June 2012