Aerosol Spray Cans Essay
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
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.
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