Aerosol propellants are the driving force behind spray, foam and mist delivery. Over time, the industry has evolved through multiple propellant technologies, from traditional hydrocarbons to next-generation synthetic gases and increasingly, inert gases such as nitrogen.
Each propellant type offers different advantages and limitations in terms of performance, safety, environmental impact and formulation compatibility. Understanding these differences is essential when deciding which is suitable for your product and formulation.
What Are Aerosol Propellants?
An aerosol propellant is a liquefied or compressed gaseous element. Propellants maintain the pressure inside the can, keeping the product confined. Liquefied propellants exist in balance with the product, while compressed gas propellants occupy the space above the liquid formulation.
When the valve is activated, the propellant expands, forcing the product up the dip tube and out of the nozzle.
Through our valve manufacturing process, this mechanism has been optimised to ensure consistent spray patterns across thousands of actuations — a critical factor in product quality and consumer satisfaction.
Types of Aerosol Propellant Gas
Compressed And Inert Gas Propellants
Compressed gases exist only in the gas phase inside the can. As product is dispensed, internal pressure gradually decreases. Without advanced valve technology – such as Salvalco’s Eco-Valve – performance can be inconsistent, making pressure management essential.
Nitrogen (N₂) Aerosol Propellant – The Preferred Inert Gas
What It Is:
Nitrogen is a naturally occurring inert gas that makes up approximately 78% of the air we breathe. When used as an aerosol propellant, it provides a circular closed-loop system.
Key Characteristics:
- Completely non-flammable
- Chemically inert and odourless, with no interaction or oxidation of the formulation
- Zero hydrocarbon VOC contribution
- Abundant and environmentally neutral
Performance Considerations:
As a compressed gas, nitrogen does not liquefy inside the can. Advanced valve technologies such as Salvalco’s Eco-Valve are engineered to manage pressure decay, delivering a fine, consistent spray comparable to traditional liquefied propellants.
Key Benefits Of Nitrogen:
- Eliminates flammability risk
- Removes hydrocarbon propellants entirely
- Supports cleaner formulations and sustainability claims
- Enables premiumisation and higher-margin product categories
- Future-proof against regulatory change
Carbon Dioxide (CO₂) Propellant
What It Is:
A non-flammable compressed gas commonly used in food applications.
Key Characteristics:
- Non-flammable
- Readily available
- Suitable for selected non-cosmetic uses
Limitations:
- Significant pressure drop during use
- Limited fine spray control
- Can interact with water-based formulations
- Identified as a contributor to climate change
CO₂ is effective in niche applications but is less suited to high-quality personal care sprays.
Compressed Air In Aerosols
What It Is:
Filtered and dried atmospheric air used as a propellant.
Key Characteristics:
- Non-flammable
- No hydrocarbon content
- Easily available
Limitations:
- Contains oxygen and moisture
- Less chemically inert
- Can affect oxidation-sensitive formulations
Compressed air offers safety benefits but lacks the inertness required for many modern formulations.
Other Compressed Gas Examples
What They Are:
Specialist gases such as nitrous oxide (N₂O), argon and helium are capable of partial liquefaction under pressure.
Their use is typically limited to specialist food and pharmaceutical applications.
Key Characteristics:
- Non-flammable
- Rapid expansion
Limitations:
- High global warming potential (notably N₂O)
- Unsuitable for most consumer aerosol products
- Significantly higher cost than nitrogen
- Poor spray control and limited availability
While inertness is essential, nitrogen offers the optimal balance of performance, cost and availability.
Liquefied Gas Propellants
Liquefied gases remain the most common aerosol propellants. They exist as both liquid and vapour inside the can, maintaining relatively constant pressure as product is dispensed. However, they are flammable, hydrocarbon-based and increasingly subject to regulation.
Liquefied Petroleum Gas (LPG)
Propane, Butane, Isobutane
What It Is:
LPG is a blend of hydrocarbons available at various pressure ratings and has historically been the most widely used aerosol propellant. It is a non-renewable by-product of oil and gas processing.
Key Characteristics:
- Stable pressure and consistent spray performance
- Established global supply chain
Limitations:
- Flammable
- Price volatility and availability risks
- Dilutes formulations
- Toxic when inhaled
- Contributor to aerosol abuse
- Hydrocarbon VOC emissions
- Increasing regulatory and sustainability pressure
While LPG delivers reliable performance, its flammability and environmental profile are driving demand for safer alternatives.
Dimethyl Ether (DME)
What It Is:
DME is a liquefied ether gas with solvent properties, making it suitable for certain water-based formulations.
Key Characteristics:
- Water solubility
- Good pressure consistency
- Can dissolve active ingredients
Limitations:
- Flammable
- Price volatility
- Dilutes formulations
- Toxic when inhaled
- Hydrocarbon VOC contribution
- Odour and formulation interactions require control
DME offers formulation flexibility but retains many of the drawbacks associated with LPG.
Specialist Propellants (HFCs / HFOs)
e.g. HFC-134a, HFC-152a, HFO-1234ze (Solstice®), HFO-1234yf
What They Are:
Synthetic gases introduced to replace ozone-depleting CFCs. HFOs are designed to offer ultra-low global warming impact.
Key Characteristics:
- Good spray performance
- Non-ozone-depleting
- Generally non-flammable or mildly flammable
Limitations:
- High global warming potential (HFCs)
- Global phase-out under climate regulations
- Significantly higher cost
- Synthetic chemistry concerns
How To Choose The Right Aerosol Propellant
The evolution of aerosol propellants reflects the industry’s shift toward safer, lower-impact technologies. While liquefied gases provide pressure stability, they introduce trade-offs in flammability and sustainability.
Inert gases – particularly nitrogen – offer a fundamentally different approach by removing hydrocarbons entirely while maintaining high-quality spray performance through intelligent valve design.
Salvalco’s Approach To Aerosol Valve Technology
Salvalco’s patented Eco-Valve technology enables the effective use of nitrogen and other inert gases in applications traditionally dependent on liquefied hydrocarbons – delivering safety, sustainability and performance without
compromise.