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Aerosol Technology

Basic Aerosol Can Technology

When you use an aerosol product, you probably don’t think about what’s going on inside that can. But an aerosol can is actually a complex piece of machinery that helps deliver a steady, concentrated stream of whatever product you desire, from whipped cream to antiseptics.

Of course you need things like a valve, an actuator, a dip tube and other parts to make it all work smoothly.

How an Aerosol Can Works

Aerosols rely on a basic principle of physics: a gas under enough pressure will turn into
a liquid, and when that pressure is relieved will expand and turn back into a gas. That process is called vaporization. An aerosol can is kept closed by the stem gasket, which seals the opening under the button.

This gasket is kept in place by a spring inside the housing. When the button is pressed,
it pushes the valve stem down against the spring, relieving the pressure that keeps the gasket sealed. When the seal opens, the higher pressure inside the can pushes the product up through the dip tube and out the valve.

A controlled amount of propellant in the product vaporizes as it leaves the can, creating a spray or foam. A small amount of liquefied gas propellant still in the container also vaporizes, keeping the pressure constant.

The combination of product and propellant is finely tuned to produce just the right concentration, spray pattern and particle size to make the product most effective.

Components of Aerosol Delivery System

Head Space

Enough space must be left in the can when it is filled and sealed to allow some of the propellant to exist in its gaseous form, maintaining a constant pressure.

Propellant

An inert gaseous compound under pressure. The propellant serves several purposes:

  • It pushes the product out of the can
  • It vaporizes after leaving the container, producing a spray or foam.
  • In most cases, it also acts as a solvent for the product.

In the U.S., the most common aerosol propellants are liquefied gases, usually naturally occurring hydrocarbons such as propane or butanes. Approximately 10 percent of today’s aerosols use compressed gases, such as carbon dioxide or nitrogen, as propellants. While less expensive than liquefied gases, compressed gases are effective propellants only with certain types of products. Chlorofluorocarbons (CFCs) are not used in American-made aerosols, except for a few uses allowed by the U.S. Environmental Protection Agency. These exceptions, which are health and pharmaceutical products, represent less than one percent of the U.S. aerosol market and even these uses are being phased out as formulations with non-CFC propellants are approved as suitable alternatives.

Product

A liquid blend of active ingredients, such as soaps or disinfectants, and inert ingredients needed to dissolve, dispense or stabilize the product. Because the aerosol container is hermetically sealed, the product is protected from contamination, evaporation or user contact. The aerosol delivery system often allows the product to be more concentrated and applied with more control than other packaging forms.

Can

More than 80 percent of aerosol containers are made of steel with a thin coating of tin. The steel used to make aerosol cans contains about 25 percent recycled metal. Empty aerosol containers are as recyclable as other steel cans. The tin is recovered during processing, plastic components are consumed during reheating, and in today’s industrial-scale recycling facilities, small quantities of propellant or product left in the can present no hazard. Of the remaining 20 percent, most are made of aluminum, a small percentage are glass.

Can Base

The curved shape of the can’s base counters the pressure of the propellant inside, and creates a “valley” so that all product can be reached by the dip tube and used.

Aerosol product Benefits

One of the earliest benefits from aerosol products came in World War II when the American military needed a way to protect soldiers from disease carrying mosquitoes. The solution to that problem was development of aerosol technology to deliver insect repellant from a spray can. Since then aerosol products have become a significant part of modern life; making life easier and protecting our health.

Today’s aerosol products improve our quality of life in many ways. They provide benefits in medical treatment, health care, pest control, disease prevention, personal care and hygiene, and household automotive and industrial cleaning and maintenance.

Aerosol containers give consumers the use of products unavailable in any other form. Only an aerosol container can provide the variation of propellant pressure and the wide range of spray patterns and particle sizes that make possible products specially designed for specific consumer needs such as:

  • Long-distance spray insecticides protect humans from harmful insects without exposure to bites or stings.
  • Asthmatic inhalers produce a mist fine enough to penetrate deeply into the bronchial area
  • Specially formulated insecticides penetrate behind cabinets and walls to remove vermin in homes, schools and work areas.
  • First aid products can be applied without direct contact and can protect the damaged area from air contact.
  • Lubricating products can be applied to hard-to-reach machine parts and to machinery in operation.
  • Contact lens solutions in a spray form eliminate the need to touch the lens itself.
  • Stable foam products, such as shaving cream and furniture polish, cannot be created in any other way.

Aerosol product also provide benefits in other areas including:

Safety:

Aerosol cans are hermetically sealed, so their contents cannot leak or spill. And aerosol containers are tamper-resistant and tamper- evident.

Efficiency:

Aerosol containers are designed to deliver the right amount of product exactly where it’s needed. Using an aerosol package reduces waste and spillage

Cost-Effectiveness:

Aerosol containers control the particle size, the spray pattern, the volume dispensed per second and the concentration of the spray for maximum effectiveness. The hermetically sealed package protects the product and extends its useful life; aerosol paints and finishes, for example, can be stored without risk of evaporation.

Clean and Sanitary Use:

Aerosol products can be applied without contact, protecting users from mess, germs and, in case of burns or lacerations, with a minimum of pain. Family members can hygienically share aerosol personal care products. In addition, the sealed can prevents any product contamination.

Special Products:

Aerosol containers give consumers the use of products— from shaving cream and long-distance spray insecticides to asthma inhalers and other medical products—which would be unavailable otherwise.

Convenience:

Aerosol containers are spill proof, which is helpful for medical and personal care products used by travelers, children, nurses and the elderly. They eliminate the need for mixing containers and applicators. They can be stored and used in the same container, often for long periods of time.