Aerosol propellants are a key technology that is indispensable in modern life. Aerosol products are ubiquitous in our daily lives. From personal care products to household cleaners to industrial applications, aerosols have become an important part of our lives. As the core element of an aerosol system, aerosol propellants play a vital role in product spraying and dispersion.
This guide aims to provide you with a comprehensive understanding of aerosol propellants, including how they work, their types, environmental impacts, and future development trends.
How Aerosol Cans Work
Aerosol cans are an efficient and convenient product packaging and dispensing system. It uses pressure to push the contents out of the container to form fine droplets or foam. The working principle of aerosol cans relies on the synergy of several key components, among which the propellant plays a vital role. The working principle of aerosol cans utilizes the pressure and atomization ability of the propellant to achieve efficient and controllable delivery of the product.
Key components of aerosol cans
A typical aerosol can consists of a container, a valve, a nozzle, and a propellant.
Container: A pressure vessel used to store products and propellants, usually made of aluminum or steel.
Valve: A mechanical device that controls the flow of products. When the valve is opened, the contents are pushed out of the container under pressure.
Nozzle: A component that atomizes the product and guides the direction of the spray. The design of the nozzle affects the atomization quality and spray morphology.
Propellant: A gas or liquefied gas that provides pressure and helps atomize the product. The propellant mixes with the product and pushes it out of the container when the valve is opened.
The role of propellants in aerosol systems
Propellants are the core of aerosol systems and play a key role in product delivery and atomization:
Provide pressure: Propellants provide a constant high-pressure environment in the container, allowing the product to be quickly pushed out when the valve is opened.
Atomize product: Propellants mix with the product and expand rapidly during the spraying process, dispersing the product into fine droplets or foam.
Control spray: Different propellant formulations and ratios can affect the speed, density and morphology of the spray to meet the needs of different products.
Product spraying mechanism
When the user presses the nozzle of the aerosol can, the valve opens to release a mixture of propellant and product. This process can be divided into several stages:
Pressure release: After opening the valve, the high-pressure environment in the container forces the propellant and product to flow out quickly.
Atomization: The propellant expands rapidly during the spraying process, dispersing the product into fine droplets or foam.
Spray: The atomized product is sprayed out at high speed through the nozzle to form a uniform, fine mist or foam.
Dispersion: The sprayed product is further dispersed in the air to form finer droplets, increasing the contact area with the target surface.
Types of Aerosol Propellants
As a key component of aerosol products, the choice of aerosol propellant plays an important role in product performance, safety and environmental impact. Common aerosol propellants can be categorized into three main types: compressed gases, liquefied gases and hydrochlorofluorocarbons (HCFCs), each of which has its own unique characteristics and application scenarios.
Compressed Gases
Compressed gases are commonly used aerosol propellants, which exist in gaseous form at room temperature and are stored in containers under pressure. Common compressed gas propellants include
Nitrogen (N2): colorless, odorless, non-toxic inert gas, widely used in food-grade aerosol products.
Carbon dioxide (CO2): colorless, odorless gas, commonly used in fire extinguishers, air guns and other high-pressure aerosol products.
Advantages of compressed gas propellants:
High safety: Most compressed gas propellants are non-flammable, non-toxic, and pose little harm to humans and the environment.
Low cost: compressed gases such as nitrogen and carbon dioxide are relatively inexpensive, which is conducive to reducing product costs.
Good stability: compressed gas is chemically stable, not easy to react with the product, which is conducive to prolonging the shelf life of the product.
Disadvantages of compressed gas propellant:
Unstable pressure: With the use of the product, the pressure in the container gradually decreases, resulting in a decline in spray performance.
Limited atomization: The relatively weak atomization capability of compressed gas may affect the spray quality and coverage of the product.
Liquefied gases
Liquefied gases are another commonly used type of aerosol propellant, which exist in liquid form at room temperature and high pressure, and vaporize rapidly during the spraying process to provide propulsion. Commonly used liquefied gas propellants include
Butane (C4H10): a colorless, flammable liquefied gas widely used in personal care and household cleaning aerosol products.
Isobutane (C4H10): isomer of butane, similar to butane, often mixed with butane.
Propane (C3H8): colorless, flammable liquefied gas, commonly used in industrial and automotive care aerosol products.
Advantages of liquefied gas propellants:
Good atomization: The liquefied gas vaporizes quickly during the spraying process, which effectively atomizes the product and improves the spraying quality.
Stable pressure: the liquefied gas can maintain a constant saturated vapor pressure in the container to ensure the consistency of the product spray performance.
Wide range of application: Different liquefied gas propellants can meet the performance requirements of various products and are suitable for a variety of application scenarios.
Disadvantages of LPG propellant:
Flammable and explosive: most of the liquefied gas propellants are flammable and explosive substances, there are certain safety hazards.
Environmental impact: Some LPG propellants have a negative impact on the ozone layer and global warming, and face increasingly stringent environmental regulations.
Sol-gas propellants
Sol-gas propellants are an emerging class of aerosol propellants that are characterized by their ability to dissolve completely in the product formulation, forming a homogeneous, stable solution. Unlike traditional compressed and liquefied gas propellants, sol-gas propellants do not form a separate gas or liquid phase in the container, but rather mix fully with the product at the molecular level.
Common sol-gas propellants include:
Dimethyl ether (DME): a colorless, flammable gas that can be dissolved in a variety of organic solvents and water at room temperature.
Hydrofluoroolefins (HFOs): a new class of fluorinated hydrocarbon compounds with low global warming potential and zero ozone depletion potential.
Advantages of sol-gas propellants :
Good product stability: The propellant is well mixed with the product, reducing the risk of phase separation and precipitation and extending product shelf life.
Excellent atomization: sol-gas propellants promote product atomization at the microscopic level, improving spray quality and coverage.
High formulation flexibility: sol-gas propellants are compatible with a wide range of product formulations, providing more options for formulation design.
Challenges with sol-gas propellants:
Pressure control: As the propellant is mixed with the product, the pressure in the vessel can be affected by the product formulation and needs to be precisely controlled.
Valve design: Sol-gas propellants place higher demands on valve sealing and material compatibility, requiring specialized design and testing.
Environmental impact of aerosol propellants
Conventional aerosol propellants, such as CFCs and hydrocarbons, have significant environmental impacts; CFCs can severely damage the ozone layer, leading to an increase in harmful ultraviolet radiation. Hydrocarbon propellants such as butane and propane are powerful greenhouse gases that contribute to global warming. In response to these challenges, governments have introduced a series of regulations and international agreements, such as the 1987 Montreal Protocol, to phase out hazardous propellants and promote a transition to more environmentally friendly alternatives. Therefore, in the next chapter, we will detail innovations in the field of aerosol propellants.
Innovation in Aerosol propellant technology
The aerosol industry is constantly seeking innovative propellant technologies to improve product performance, reduce environmental impact and meet increasingly stringent regulatory requirements. In recent years, several breakthrough innovations have come to the forefront, opening up new avenues for aerosol propellant development.
Bag-on-Valve (BoV) Technology
Bag-on-Valve (BoV) technology is a major innovation in aerosol packaging. Unlike traditional aerosol systems, BoV technology packages the product in a flexible bag, while the propellant fills the space between the bag and the container.
How BoV technology works:
When the user presses the nozzle, the propellant is pressurized, squeezing the bag and pushing the product out. The bag shrinks to maintain the same volume as the remaining product, ensuring that the propellant does not come into direct contact with the product. When the nozzle is closed, the bag stops contracting and the product stops flowing.
BoV technology offers several benefits for product performance and sustainability:
Complete product isolation: The propellant is separated from the product, eliminating the risk of cross-contamination and chemical reactions.
Consistent spray performance: BoV technology ensures consistent spray performance due to constant propellant pressure, maintaining good atomization even when the product is exhausted.
Spraying at any angle: BoV technology allows spraying at any angle, even upside down, improving the user experience.
Excellent environmental performance: BoV technology can use compressed air, nitrogen and other environmentally friendly propellants, reducing the impact on the ozone layer and global warming.
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Other emerging propellant alternatives
In addition to BoV technology and the previously mentioned sol-gas propellants, the aerosol industry is actively researching other environmentally friendly propellant alternatives to replace traditional hydrofluorocarbons (HFCs) propellants, of which we as well as mentioned hydrofluoroolefins (HFOs) earlier:.
Hydrofluoroolefins (HFOs) are a new class of fluorinated hydrocarbon compounds with low global warming potential (GWP) and zero ozone depletion potential (ODP), and are considered to be an ideal alternative to HFCs. HFOs are comparable to HFCs in terms of atomization performance, pressure characteristics, etc., but have a much lower environmental impact.
Compressed air is a simple, economical and environmentally friendly propellant choice. Although its atomization performance is not as good as that of liquefied gases, compressed air is a viable alternative for certain products that require lower spray quality, such as brush foams.
Nitrogen is another environmentally friendly propellant that is chemically stable, non-toxic, odorless, and has no effect on the ozone layer or global warming. Nitrogen is commonly used in food-grade aerosol products such as cream and cooking oil sprays.
How to choose an aerosol propellant
When selecting an aerosol propellant, manufacturers need to consider several key factors to ensure product performance, safety and compliance. These factors include product compatibility, environmental impact, safety and regulatory requirements, performance and spray characteristics, and cost effectiveness.
Compatibility of propellants
Product compatibility is the primary consideration. The propellant must be compatible with the active ingredient and other excipients in the formulation without causing any chemical reaction or degradation. For example, some propellants may react with specific flavors or solvents, resulting in product deterioration or failure. Therefore, manufacturers need to conduct detailed compatibility testing to ensure the compatibility of the propellant with the product formulation.
| Propellant Types | Common Compatibility Issues |
| Hydrocarbon propellants | May react with some organic solvents and flavors |
| Chlorofluorocarbon propellants | May be incompatible with certain plastics and rubber materials |
| Compressed gas propellants | May affect stability of pH-sensitive formulations |
Environmental Impact of Propellants
Environmental impact is another important consideration. Aerosol propellants contribute to the ozone layer and global warming, so manufacturers need to select propellants that minimize their environmental impact. Currently, the industry is phasing out high ozone depletion potential (ODP) and high global warming potential (GWP) propellants in favor of more environmentally friendly alternatives such as hydrofluoroolefins (HFOs) and compressed gases.
Safety and regulatory requirements
Safety and regulatory requirements are also key factors. Propellants must meet relevant safety standards and regulatory requirements, such as the U.S. EPA's SNAP program and the European Union's F-Gas regulation. Safety characteristics such as flammability, toxicity and reactivity also need to be carefully evaluated. For example, hydrocarbon propellants such as propane and isobutane are flammable and require special care in storage and use.
Performance and spray characteristics
Performance and spray characteristics have a direct impact on the user experience of a product. Different propellants can provide different atomization effects, spray rates and spray angles. For example, liquefied gas propellants typically provide a finer atomization and higher spray rate, while compressed gas propellants may produce a wetter spray and lower spray rate. Manufacturers need to select the propellant that will provide the best performance based on the specific application of the product and the preferences of the target consumer.
| Type of Application | Recommended Propellant Type |
| Personal care products (e.g., hairspray, deodorant) | Liquefied gas propellants (e.g., butane, isobutane) |
| Household cleaning products (e.g., air fresheners, furniture polish) | Compressed gas propellants (e.g., nitrogen, carbon dioxide) |
| Food grade applications (e.g., cooking oil sprays, creams) | Inert gas propellants (e.g., nitrogen, carbon dioxide) |
Cost Effectiveness
Finally, cost-effectiveness is also a factor that needs to be weighed when selecting a propellant. Different propellants have different prices, availability, and handling requirements that affect the final cost of the product. For example, using compressed air as a propellant may be more economical than using liquefied gas, but its performance may not meet the requirements of some applications. Manufacturers need to find the optimum balance between performance and cost in order to provide a high quality, cost-effective product.
How to use aerosol propellants safely
Safety is a primary concern during the manufacture, storage and use of aerosol propellants. Many commonly used propellants (e.g., propane, butane, and isobutane) are flammable and improper handling can result in fire or explosion. This section describes key safety measures to minimize risk and protect personnel and facilities.
Safety in storage and handling
Storage environment: cool, dry and well ventilated
Keep away from heat, open flames and other ignition sources.
Clear signage and warning labels
Restrict access to unauthorized personnel
Use specialized equipment and piping for transfer and handling.
Handling by trained persons
Safe storage conditions for propellants
| Propellant Type | Storage Temperature | Precautions |
| Hydrocarbons (e.g., propane, butane) | < 45°C | Keep away from heat and open flames |
| Carbon dioxide | < 50°C | Avoid direct sunlight |
| Nitrogen | < 50°C | Avoid high temperatures and pressurized environments |
Fire and Explosion Protection
Production and storage areas should be equipped with appropriate fire fighting equipment such as fire extinguishers, fire detectors and automatic sprinkler systems. Electrical equipment and wiring should be of explosion-proof design to prevent explosions caused by electrical sparks. Smoking, open flames or other spark-producing activities are prohibited in propellant storage and use areas.
Case: Butane propellant filling plant fire and explosion protection measures
Install explosion-proof electrical equipment and lighting
Use conductive flooring and anti-static work clothes.
Equip sufficient number of portable fire extinguishers and fixed fire-fighting systems.
Conduct regular fire and explosion prevention training and emergency drills.
Personal protective equipment (PPE)
Personal protective equipment (PPE) is an important means of protecting employees from the potential hazards of aerosol propellants. When handling propellants, employees should wear appropriate PPE, such as anti-static coveralls, protective gloves, safety glasses and respiratory protection equipment.PPE should be inspected and maintained regularly to ensure that it meets safety requirements. Employees should also be trained in the proper use and maintenance of PPE.
PPE recommendations for different propellants
| Type of Propellant | Recommended PPE |
| Hydrocarbons | Antistatic coveralls, protective gloves, safety glasses, respiratory protective equipment |
| Chlorofluorocarbons | Chemical protective clothing, protective gloves, full face respirators |
| Compressed gases | Protective gloves, safety glasses, respiratory protective equipment if necessary |
Safety management system
Establish safety procedures
Conduct employee safety training
Develop an emergency response plan for accidents
Conduct regular safety audits and risk assessments.
Encourage employees to actively participate in safety management
Promptly report safety hazards or accidents
Conclusion
The selection and use of aerosol propellants have a significant impact on product performance, environmental impact and user safety. As the concept of sustainable development has become more popular, the development of environmentally friendly, safe and efficient aerosol propellants has become a top priority in the industry. Among them, propellant-free aerosol technology (Bag-on-Valve, BOV for short) is gaining more and more attention as a breakthrough solution.
However, to fully utilize the advantages of BOV technology, it is crucial to choose the right filling equipment. In this regard, Weijing's bag on valve aerosol filling machine is providing manufacturers with an ideal choice with its excellent performance and reliability. To learn more, contact Weijing now.
