BOV is one of those formats that gets recommended for the wrong reasons. It is not simply "better" than a conventional aerosol: it is a different arrangement that solves specific problems, and it costs more to make.
This page sets out what is physically inside the can, what that changes for your product, where the format does not help, and the testing that does not change at all.
What is actually inside a bag-on-valve can
A BOV can holds two separate things at once. Getting this picture right makes the rest of the page obvious:
| The bag | A sealed, flexible bag bonded to the valve, holding your product Keeps the formula completely separate from the propellant |
|---|---|
| The valve | A continuous or metered valve assembly crimped onto the can opening The crimped joint is the critical seal — and the part that is easiest to get wrong |
| The propellant | Compressed gas or liquefied propellant in the space around the bag Provides the force; it is never sprayed out with the product |
| The can body | The same formed and printed aluminium body used for conventional aerosols Nothing about the can itself changes |
The propellant never becomes part of what you spray. That single fact drives almost every reason people choose this format.
What BOV changes for your product
- No propellant contact. Formulations where the propellant would be unacceptable — or where you simply do not want it on the label — can be delivered from a sealed bag.
- Sprays in any orientation. Because the product comes out of a bag instead of up a dip tube, holding the can upside down or at an angle does not starve the valve.
- Consistent delivery as the can empties. The bag collapses rather than the headspace growing, so the spray rate stays closer to constant from first use to last.
- Near-complete evacuation. Less product is left behind when the can is finished, which matters for high-value formulas.
- Viscous products become practical. Products that would clog a conventional dip tube can often be delivered from a bag.
Where BOV does not help
Being straight about the limits saves time on both sides:
- It costs more per can. The valve and bag assembly is the expensive part, and it is not something you can substitute at the last minute.
- Your filler needs the right line. The valve assembly has to be crimped and gassed in one operation. A filler set up only for conventional aerosols cannot simply switch.
- The bag film has to tolerate your formulation. Compatibility is a real question, not a formality — solvents and some actives need checking before anything is ordered.
- It does not remove any testing obligation. Every can still goes through the same 100% water-bath leak test, and crimp dimensions still have to be held.
What changes in testing and filling
From the can side, the work you would recognise does not change: the aluminium body is formed, coated and printed the same way, and every can is leak tested by immersion after crimping. What becomes more critical is crimp geometry — the seal between the valve assembly and the can opening is the leak path that matters most, so that dimension is controlled and logged like any other.
Which additional BOV-specific checks we run, and how they are recorded, is something we would rather state precisely than describe loosely: [待确认：BOV 专属的检测项目与记录方式].
When BOV is worth it
- Your formulation must not contain propellant, or you do not want it declared.
- Your product is applied at any angle — sun care, body care, after-sport.
- You need consistent output as the can empties, because the last third of the can has to perform like the first.
- Your product is too viscous for a conventional dip tube.
- The unit cost increase is small next to the value of the formula inside.
If none of those apply, a conventional aerosol will usually cost you less for the same job — and we will say so rather than upsell the more expensive assembly.
Frequently asked questions
Does the propellant touch my product in a BOV can?
No — that is the whole point of the format. The product sits inside a sealed bag and the propellant is outside that bag but inside the can, so nothing from the propellant side enters your formula. The bag is what pushes the product out as the valve opens.
Can a BOV can spray upside down?
Yes. Because the product is delivered from a bag rather than drawn up a dip tube, orientation is far less critical than in a conventional can. This is one of the main reasons BOV is chosen for sunscreens, after-sun and body products that get applied at awkward angles.
Is BOV more expensive than a standard aerosol?
The can body is comparable; the valve and bag assembly is not, and the filling line has to be set up for it. Treat BOV as a higher unit cost per can that you justify with the formulation or the user experience, not as a way to save money.
What has to be confirmed before we commit to a BOV project?
Three things: which of our can sizes can be fitted with a BOV valve [待确认：我们可做 BOV 的罐型与容量范围], the bag film's compatibility with your formulation, and whether your filler has BOV capability — the assembly has to be crimped and gassed in one operation.
Next step
Tell us the formulation, the fill volume and how the product will be used, and we will say whether BOV is the right format for it. The full range is on the product pages, and the documents you may need are listed on the certificates page — including how to read them.