A Guide to Liquid and Gas Aerosol Can Propellants

Aerosol cans have played an important role in industries and economies throughout the world since the 1920s. They were originally invented as a means of spreading insecticides for the United States military. Still, they have since been utilized to provide an effective means of dispersing countless different products, including cleaners, lubricants, shaving cream, and paints. While many people are familiar with the wide variety of applications for aerosol cans, relatively few are familiar with how they function or the propellants they use to make it all possible.

Understanding how an aerosol can works is important in understanding aerosol can propellants and their purpose. Aerosol cans are a dispersal system that relies on internal pressure to propel the product out of the can in the form of an aerosol.

Aerosol cans typically consist of some variation of these four components:

• The container
• The trigger
• The nozzle
• The straw or hose

The container is pressurized so that when the trigger is pressed, the product within the can is pushed through the straw and outward from the nozzle in the form of a fine mist or aerosol.

The contents of an aerosol can consist of two primary components:

• The product or active ingredient
• The propellant
  

The aerosol can propellant is added to create the internal pressure within the can that drives the product or active ingredients from within the can. If a propellant were not used, as the can was used up and the pressure of the can decreased, the spray would weaken and eventually stop entirely once the can’s internal pressure was equal to the external environment. This would create an uneven spray as the pressure changed and would leave unused product within the container at the end of its life. The propellant helps to maintain constant or near-constant pressure and creates a consistent spray of the product in the form of an aerosol. It also allows the user to get more of the product out of the can before running out of pressure.

There are several different types of aerosol can propellants used in aerosol cans, each providing a diverse array of advantages and disadvantages. We’ve outlined three different types of aerosol can propellants below.

Some aerosol cans use a compressed gas like nitrogen or carbon dioxide as their propellant. The advantage of compressed gas as an aerosol can propellant is that it’s very cheap, and it isn’t flammable, though other products within the aerosol can be. The disadvantage of compressed gas as an aerosol can propellant is that the pressure within the can will decrease over the life of the can. As the product within the can is used, the pressure within the can decreases, and the can will have less dispersing power because of it. Currently, only about 10% of aerosol cans use compressed gas as the propellant. Most use a form of liquid gas, which is explained below.

The most common form of aerosol can propellant is a liquefied gas like butane, isobutane, or propane. The gas is turned into liquid by pressurizing it within the can. The advantage of this system is that it provides constant pressure levels throughout the life of the can. As the product is dispersed and space in the can becomes available, the liquid gas vaporizes and fills the newly available space, allowing the can to maintain the consistent internal pressure. The disadvantage of this system is that liquid gas propellants are flammable, which increases the danger associated with their use and storage. Even so, this is still the most common form of aerosol can propellant.

Chlorofluorocarbons were used for a time as an aerosol can propellant. They provided the advantages of both liquid gas and compressed gas aerosol cans, meaning that they provided constant pressure throughout the life of the can and weren’t flammable. However, it was found that they were damaging the ozone layer, and their use in aerosol cans was discontinued in the United States in the late 1970s. In 1987, 191 countries signed an international agreement to phase out ozone-depleting substances like chlorofluorocarbons. Aerosol cans that utilize chlorofluorocarbons as a propellant are no longer allowed in the United States and many other countries.

There are three potential dangers associated with aerosol cans, stemming from their internal pressure, their propellant, and the product or active ingredients.

Because aerosol cans are pressurized, they have the potential to explode when exposed to heat or if the container is compromised. Aerosol can explosions may result in injury, damage to property, and death.

Many aerosol cans use propellants that are some combination of butane, isobutane, and propane. These are flammable and require special care when storing and in use.

The third potential danger associated with aerosol cans comes in the form of the cans’ active ingredients. Aerosol cans are used to disperse countless hazardous and flammable liquids, including insecticides, pesticides, cleaners, and paints. The dangers of each product will vary based on its active ingredients, and proper care should be taken to meet safety requirements and recommendations based on the aerosol cans’ active ingredients.

Due to the potential dangers that aerosol cans pose for users and those in their vicinity, it is crucial to store and safely dispose of aerosol cans. For the safe storage of spray paint and other aerosol cans, we recommend a safety cabinet like the Sure-Grip® EX Wall Mount Aerosol Can Safety Cabinets. They improve safety in the workplace and are designed to provide regulatory compliance.

For those looking for a safe, cost-effective, and environmentally friendly way to recycle aerosol cans, we recommend the Aerosolv® Aerosol Can Disposal System. Mounted on a standard 55-gallon drum, the Aerosolv system safely empties aerosol cans and prepares them to be safely recycled.