According to Merriam-Webster, a propellant is a gas under pressure in a can that is used to spray out the contents when the pressure is released. Good examples of common, everyday products that use propellants are aerosol products. These inert gaseous compounds under pressure serve several purposes:
- They push the product out of the can.
- They vaporize after leaving the container, producing a spray or foam.
- In most cases, they also act 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 butane. Approximately 10 percent of today’s aerosols use compressed gases, such as carbon dioxide, nitrogen, or even compressed air 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, and have been phased-out throughout the developed world under the Montreal Protocol. See more about the history of CFCs at www.aerosolproducts.org.
The chart below shows a break-down of some of the types of commonly-used propellants:
|Compressed Gas Propellants||In Gases||Carbon Dioxide
|Liquefied Gas Propellants||Hydrocarbons||Liquefied Natural Gases
(Propane, Isobutane, n-Butane, Isopentane, n-Pentane)
|Fluorocarbons||1,1 Difluoroethane (HFC-152a)
1,1,1,2 Tetrafluoroethane (HFC-134a)trans-1,3,3,3-Tetrafluoroprop-1-enetrans-1,3,3,3-Tetrafluoroprop-1-ene (HFO-1234ze)
Propellants used in today’s aerosol products are closely regulated for safety and efficacy and most are derived from pure, natural gas. In addition, most aerosol products must meet strict VOC (Volatile Organic Compound) regulations as outlined by the EPA (Environmental Protection Agency) and the CARB (California Air Resources Board), as well as any applicable regulations from the FDA (Food and Drug Administration), CPSC (Product Safety Commission), DOT (department of Transportation), EPA, or other governing bodies, depending on the product-type.
In addition to aerosol products being carefully formulated and regulated, there are many reasons why the aerosol product form continues to be a preferred product packaging choice for many types of products.
- Efficiency – Through precise product formulation and choosing the right propellant, the aerosol product form allows the consumer to get the right amount of product exactly where they need it, avoiding product waste or mess.
- Effectiveness – The ability for a product to be applied as foam, a fine mist, or a higher pressure continuous stream just wouldn’t be possible without this technology.
- Long shelf life – Because the products are hermetically sealed, they can’t evaporate over time, or spill, allowing for a very long shelf-life, which offers value to the consumer and reduces waste. Since they are never opened to air, there is no opportunity for bacteria to be introduced, and products remain sterile.
- Sustainability – Aerosol cans are made of steel or aluminum and are infinitely recyclable, and valuable in the waste stream. Please recycle when empty!