Bag-on-Valve Technology: How BOV Works, Benefits & Applications

Chapter 1: What Is Bag-on-Valve (BOV) Technology?

How Does Bag-on-Valve Technology Work?

Bag-on-Valve (BOV) technology is a barrier aerosol packaging system that keeps the product physically separated from the pressure medium inside the can. The product is stored in a flexible multi-layer bag attached to the aerosol valve, while compressed air or nitrogen is filled into the space between the bag and the container.

When the actuator is pressed, the surrounding pressure squeezes the bag and pushes the product through the valve. Unlike conventional aerosol packaging, the pressure medium does not normally mix directly with the formulation.

This product–pressure-medium separation is the core principle of Bag-on-Valve technology and makes the system suitable for many cosmetic, personal-care, pharmaceutical, food and technical aerosol applications.

To picture how a bag-on-valve works, imagine a toothpaste tube hidden inside a metal can. Instead of using your hands to squeeze the tube, the can is filled with pressurized air. When you press the spray button, that trapped air acts as an invisible hand, squeezing the bag from the outside and forcing the product out.

Bag on Valve BOV packaging system mechanism diagram

Sometimes referred to in the industry as a bag in valve, this barrier system keeps the product separated from the pressure medium throughout dispensing.

Key Components of a Bag-on-Valve System

Component	Function
Aerosol Can	Holds the complete pressurized package
BOV Valve	Connects the bag to the dispensing system
Flexible Bag	Contains the product
Pressure Medium	Compressed air or nitrogen surrounds the bag
Actuator	Controls product dispensing
Product	Remains inside the bag

The flexible barrier bag is the defining element of Bag-on-Valve technology because it keeps the product separate from the pressure medium during storage and dispensing.

Chapter 2: Bag-on-Valve Technology vs Traditional Aerosol Packaging

Traditional aerosol and Bag on Valve packaging can both provide continuous dispensing, but the internal packaging structure and filling process are different.

Feature	Traditional Aerosol	Bag on Valve (BOV)
Product & Propellant	Product and propellant share the same container space	Product is separated from the pressure medium by a flexible bag
Pressure Medium	Commonly LPG, DME or compressed gases depending on the product	Commonly compressed air or nitrogen
Product Contact	Formulation may be in direct contact with the propellant	Product remains isolated inside the bag
Spray Angle	Performance depends on the aerosol system and valve design	BOV systems can support continuous multi-angle spraying
Product Evacuation	Depends on formulation, propellant and packaging design	High product evacuation can be achieved with a properly designed BOV system
Suitable Products	Widely used for conventional aerosol products	Useful for products that benefit from product–propellant separation

Chapter 3: Benefits of Bag-on-Valve Technology

Automatic cosmetic aerosol production line machinery manufacturer

Product–Pressure Medium Separation

The product remains completely sealed inside the multi-layer barrier bag while compressed air or nitrogen stays outside it. This makes BOV essential for sensitive formulations where separation from the pressure medium is critical to maintain ingredient integrity.

Barrier Protection

The laminated barrier bag protects the formulation against oxygen, moisture, and light contamination, preventing oxidation and extending shelf life without requiring heavy preservative loads.

Continuous and Multi-Angle Dispensing

Because dispensing is powered by surrounding gas pressure squeezing the bag rather than a traditional dip tube, BOV systems support smooth, 360-degree continuous spraying at any orientation—even upside down.

Compatibility With Different Formulations

BOV technology accommodates a wide spectrum of product viscosities—from low-viscosity liquid mists to high-viscosity creams, gels, and viscous pastes—without altering propellant ratios.

High Product Evacuation Potential

With an engineered bag geometry and balanced pressure filling, a properly designed BOV packaging system achieves high product evacuation potential, minimizing residue waste inside the container.

Chapter 4: Common Bag-on-Valve Technology Applications

Bag on Valve packaging can be used for a wide range of formulations, from fine mists to creams and gels. Whether BOV is suitable depends on the product, valve, bag and dispensing requirements.

Cosmetics & Personal Care: Products such as sunscreen sprays, facial mists and toners, shaving gels and other personal-care products can use BOV when product–pressure-medium separation is desirable.

Cosmetic products using bag on valve continuous spray packaging

Healthcare & Pharmaceutical Products: BOV packaging is used for products such as saline sprays, wound-care sprays and other products where separation between the formulation and pressure medium is desirable. Equipment configuration, product-contact materials and filling requirements should be selected according to the specific product and production standard.

Food & Edible Oil Sprays: BOV can also be used for products such as edible oil sprays, where the product remains separated from the pressure medium during dispensing.

Household & Industrial Products: Selected air fresheners, cleaners and other household or industrial products may also use BOV, depending on the formulation and packaging requirements.

Chapter 5: How Bag-on-Valve Technology Changes the Aerosol Filling Process

Because the bag is attached to the valve, BOV products require a filling sequence designed specifically for this packaging system.

The typical process includes three key steps:

1. Valve + Bag Insertion: The BOV bag and valve assembly is inserted into the aerosol can.
2. Under-Cup Gassing and Crimping: Compressed air or nitrogen is charged under the valve cup while the valve is crimped onto the can in a single operation.
3. Product Filling Through the Valve: The liquid, gel, or cream formulation is dosed directly through the valve stem into the sealed barrier bag inside the pressurized container.

These steps require dedicated BOV filling equipment because pressure filling, valve crimping and product filling must work together with the specific can, valve and bag configuration.

Chapter 6: What BOV Filling Equipment Do Manufacturers Need?

Once the BOV filling process is understood, the next question for manufacturers is what equipment is needed for production.

The exact equipment configuration depends on the product, packaging format and required production capacity. Before selecting a BOV filling machine or production line, manufacturers should normally confirm:

Product type and characteristics — such as liquid, cream, gel or other formulation characteristics.
Filling volume — the required amount of product in each container.
Can dimensions — including can diameter and height.
BOV valve and bag specifications — the machine and tooling need to match the actual packaging components.
Pressure medium — typically compressed air or nitrogen, depending on the product and packaging requirements.
Required production capacity — different equipment configurations are suitable for different output requirements.
Product-contact material requirements — the appropriate material should be selected according to the formulation and production requirements.
Level of automation — semi-automatic equipment can offer greater flexibility for smaller production volumes or multiple SKUs, while fully automatic lines are better suited to higher and more continuous production requirements.

For manufacturers starting or expanding BOV production, the equipment can range from individual filling machines to a complete production line. The appropriate configuration should be selected according to the actual product, packaging format, target output and factory conditions.

AILE provides BOV filling machines and complete BOV aerosol filling lines for different production requirements.

Chapter 7: FAQ About Bag on Valve

What is Bag-on-Valve technology?

Bag-on-Valve (BOV) technology is a barrier aerosol packaging system where the formulation is hermetically sealed inside a flexible multi-layer bag attached to an aerosol valve. Compressed air or nitrogen surrounds the bag inside the container, acting as the dispensing pressure medium without mixing with the product.

What is the difference between Bag-on-Valve technology and traditional aerosol technology?

The core difference lies in product–propellant contact. Traditional aerosols mix the product directly with liquefied propellants (such as LPG or DME) inside the same container cavity. Bag-on-Valve technology isolates the product within a laminated barrier bag, using eco-friendly compressed gas solely as an external squeezing medium, ensuring pure formula dispensing and 360-degree spray capability.

What does BOV stand for?

BOV stands for Bag on Valve. It is an aerosol packaging system in which the product is contained inside a flexible bag attached to the valve, while the pressure medium remains outside the bag and inside the can.

What does a Bag on Valve system do?

A Bag on Valve system separates the product from the pressure medium inside the aerosol can. When the valve is activated, the pressure surrounding the bag pushes the product out through the valve while the product remains contained inside the bag. This separation makes BOV suitable for products where direct contact between the formulation and the pressure medium is undesirable.

What is the difference between BOV and traditional aerosol packaging?

The main difference is how the product and pressure medium are stored. In a traditional aerosol system, the product and propellant are generally contained within the same internal space. In a BOV system, the product is held inside a flexible bag while the pressure medium remains outside the bag. The two systems therefore require different filling processes and equipment configurations.

What gas is used for Bag on Valve?

Bag on Valve systems commonly use compressed air or nitrogen as the pressure medium. The appropriate choice depends on the product, packaging system and production requirements. Manufacturers should confirm the pressure medium together with the BOV valve, bag and filling-equipment configuration before production.

What products can use Bag on Valve packaging?

BOV packaging can be used for a wide range of products, including facial and body sprays, cosmetic and personal-care products, sunscreen sprays, edible oil sprays, saline sprays, wound-care sprays and selected household or industrial products. Whether BOV is suitable for a particular product depends on factors such as the formulation, viscosity, filling volume, valve and bag specifications, and dispensing requirements.

What equipment is needed to fill BOV aerosols?

BOV production requires equipment capable of handling the specific filling process, including under-the-cup gassing, valve crimping and product filling through the valve. The appropriate setup may be a semi-automatic BOV filling machine or a complete automatic BOV filling line, depending on the required output, product, packaging format and factory conditions.

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