Aerosol Spray Can Essay, Research Paper

Spray cans produce an aerosol, the technical term for a very

fine spray. They do this by means of a pressurized propellant, which

is a liquid that boils at everyday temperatures. Inside the can, a

layer of gaseous pressure increased, and eventually it becomes so

high that boiling stops. when the nozzle is pressed, the gas pressure

forces the product up the tube in the can and out of the nozzle in a

spray or foam. The propellant may emerge as well but, now under

less pressure, it immediately evaporates.

First patented in the US in 1941, aerosol spray cans have been

used as convenient packages for an ever increasing range of

products including paints, insecticides, and shaving cream to name

a few. The can is filled with the product to be sprayed and the

propellant, a compressed gas such as butane or Freon. The gas is

partly liquefied by the pressure in the can, but there is a layer of free

gas above the liquid. As the can empties liquefied gas vaporizes to

fill the space.

The valve is normal held shut by the pressure in the can, and

by the coil spring directly below the valve stem. When the push

button is pressed, it forces the valve stem down in its housing,

uncovering a small a small hole which leads up through the stem to

the nozzle in the button. This allows the product to be forced up the

dip tube by the gas pressure in the can. The nozzle is shaped to give

a spray or a continuous stream.

To produce a fine mist, a propellant is used which mixes with

the product. The two leave the nozzle together and the propellant

evaporates a soon as it reaches the air, breaking the product in to

tiny droplets. The same technique used with a more viscous liquid

and a wider nozzle results in a foam. For a continuous stream of

liquid or more viscous material, a nonmixing propellant is used, and

the dip tube reaches into the product.

The widespread use of aerosol cans using Freon as the

propellant led scientists to believe by the late 1970s that the ozone

layer in the upper atmosphere, which filters out harmful Ultraviolet

radiation from the sun, could be destroyed by the large quantities of

fluorocarbons in the gas being release into the air. Federal controls

were introduced to ban the use of Freon, and other propellants are

now employed, notably butane which, however is dangerously

flammable.

Among young people in United States, conventional drug or

alcohol abuse has given away-for an increasing number of teen-

agers-to a practice called ‘huffing’, inhaling chemicals found in

aerosol sprays and other common household items such as cigarette

lighters, paint thinner, gasoline. Inhalant abuse is becoming

increasingly common among young middle-class teenagers. It is a

cheap, and sometimes deadly, thrill.

Yoon, Byung

Period 1

Aerosol Spray Cans

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