Hey everyone, it’s Jake from the Bag-on-Valve aerosol filling machine team here, and today we’re diving into something I get asked about all the time: how do we actually fill super viscous products with Bag-on-Valve (BoV) equipment? Let’s be real—you’ve probably got a product you’re working with that’s thick, gloopy, hard to move: maybe a hair gel that’s so good it’s like pumping liquid sunshine, a thick lotion that feels like silk but won’t pour, or even a high-viscosity adhesive that’s way too thick for regular aerosols. Regular aerosol machines struggle with this big time—they clog, they underfill, the product doesn’t spray right, it’s a mess. But BoV machines? We built them to handle exactly this. Let’s break it down like we’re chatting over a coffee, no stuffy jargon here. Bag-on-Valve Aerosol Filling Machine
First off, let’s remember what makes BoV different from regular aerosols. Regular ones mix product and propellant in one can, so if your product’s super thick, it has to move through a tiny dip tube that’s prone to getting clogged. BoV splits it up: the product goes into a flexible bag inside the can, and propellant is outside the bag, pushing the product out. That separation is the game-changer for viscous stuff, but we still have to design the filling process to work with that bag and the thick product. Let’s start with the core part: the feeding system for the viscous product. If you’ve got something that’s like honey mixed with glue, just pumping it with a regular pump isn’t going to cut it—you’d get air bubbles, or the pump would seize up, or you’d get inconsistent fills.
What do we do here? We use positive displacement pumps, but not just any—we size the chamber and the internals specifically for viscosity. For low-viscosity products, a regular peristaltic pump works, but for stuff that’s over, say, 10,000 cP (that’s centipoise, the unit we use for viscosity—think toothpaste is around 10,000, hair gel might hit 50,000), we switch to gear pumps or lobe pumps. Why? Positive displacement pumps move a fixed amount of fluid per cycle, so we can dial in the exact fill volume we need, no matter how thick the product is. Gear pumps work by using interlocking gears to push product through the chamber, and we can adjust the speed to match the viscosity—slow enough so the thick product doesn’t shear, fast enough so it doesn’t hang up. Lobe pumps are even gentler for shear-sensitive viscous products—shear is when you apply too much force and the product’s structure breaks down, which is bad if you’re filling lotion or food-grade thick syrups. We tune the pump’s torque settings too; if the product gets too thick mid-fill (like if the temperature drops a little, which makes it thicker), the pump’s smart sensors pick up the increased torque and adjust the speed automatically. No more underfills because the pump couldn’t push the product through.
Next, we have to handle the bag. BoV bags are usually made of laminated plastic or aluminum, designed to stretch as the product is filled and shrink as it’s dispensed. But if you’re filling something super viscous, the bag material and the fill nozzle have to work together. If the nozzle is too small, the viscous product gets stuck and can’t flow into the bag evenly, which causes air gaps or inconsistent fill weights. So we size the fill nozzle diameter based on the viscosity—for thick products, we use wider nozzles, maybe with a tapered end to help the product flow into the bag without splashing or getting trapped at the top. We also do a pre-fill evacuation step, which is key. If you fill a thick viscous product into a bag with air, that air gets stuck in the product or the bag, and when you put the valve on, the air expands and can mess up the spray, or even push the product out of the wrong place. We pull a mild vacuum on the bag before filling—enough to suck out any loose air, but not so strong that it collapses the bag or deforms the product. For really high-viscosity stuff, we might even heat the product slightly before filling, but only just enough to lower the viscosity a little, not enough to change the product’s properties. Wait, I know what some of you are thinking—heating would ruin things like natural lotions or certain adhesives, so we only use that when the product is heat-stable, and we’ve got temperature controls that are super precise, like within 1 degree Fahrenheit, so no hot spots.
Then there’s the filling process itself, which is automated, obviously, but the automation is tailored for viscous products. Regular filling machines might just shoot product in fast, but with thick stuff, that leads to product building up in the nozzle or on the bag walls, and not getting a uniform fill. We use a slow-start, fast-in, slow-stop fill profile. So the pump starts at a low speed to get the product flowing into the bag without splashing or pushing air, then speeds up to the set volume rate for most of the fill, then slows down again at the end to avoid overfilling the bag or dripping product from the nozzle when it retracts. We also have a drip-free nozzle design—because if you’re filling something thick, a little drip at the end can get on the valve or the outside of the can, which is a waste and a mess. The nozzle retracts quickly and seals itself once the fill is done, so no drips. We test this with every product we work with—last month we had a customer filling a 70,000 cP heavy-duty lubricant, and the standard nozzle they were using was leaving 2-3 grams of product dripping, which added up to thousands of dollars in waste. We swapped them to a tapered nozzle with a spring-loaded seal, and that drip was gone entirely.
Wait, another big thing: pressure control. When you’re dealing with BoV, after filling the product into the bag, we have to add propellant into the space between the bag and the can wall. For viscous products, the pressure when adding propellant matters because the bag is already full of thick product—too much pressure and you can rupture the bag, too little and the product won’t dispense properly. We use digital pressure regulators that are linked to the fill system, so once the product fill is done, the regulator measures the bag’s internal pressure (wait, no, the bag is inside the can, so we measure the headspace between bag and can) and adjusts the propellant pressure accordingly. For thick products, we add a little more propellant pressure than we would for thin ones, because it takes more force to push the thick product out of the bag through the valve. We also make sure the valve itself is sized right for viscous products—valves with larger orifices let the thick product flow easier, instead of getting stuck in a tiny opening. I’ve had customers come to us with BoV fill machines that weren’t made for their viscous stuff, and their valve orifices were too small, so they’d get inconsistent spray—some times nothing, some times a glob of product. We swap out the valves for larger ones, and that fixes 90% of the problem right there.
What about common issues we actually run into with viscous products? Clogging is the big one. When thick product dries or thickens in the fill line or nozzle, that’s a headache. We designed our machines with quick-disconnect parts for the product path—pump, lines, nozzle—so you can take them apart and clean them in minutes, not hours. We also have a solvent flush cycle that’s automated for product changes. If you’re switching from filling a thick lotion to a thick hairspray, you can run a small amount of cleaning solvent through the lines and pump, and the machine’s sensors make sure all the old product is gone, no cross-contamination. For really stubborn viscous products, like epoxy, we even have heated lines that keep the product at a consistent temperature so it doesn’t thicken and clog mid-fill. But again, we only use heating when the product can handle it—no hot chocolate or heat-sensitive foods, obviously.
I should also mention that we test every single machine we build for viscous product fills. When a customer orders a BoV machine, we ask them to send us a small sample of their product—no need to send gallons, just a pint or so—and we run test fills in our lab. We adjust the pump speed, nozzle size, pressure settings, even the bag material to make sure the fill is consistent, no clogs, no air bubbles, exactly the volume they need. Last quarter we had a customer who made a thick, natural sunscreen that was 45,000 cP, and their old machine was getting 10% underfills because the product wouldn’t flow. We tested their product, tweaked the lobe pump speed, used a wider nozzle, and cut their underfills to less than 1%, way below industry standards. That’s the stuff we’re good at—customizing the machine to their product, not just using a one-size-fits-all.
Wait, let’s talk about why this matters for your business, not just the tech. If you’re filling viscous products, downtime is money. If your machine is always clogging, or getting fills that are too inconsistent, you’re wasting product, missing deadlines, and annoying your customers. Our BoV machines for viscous stuff have been running 24/7 for some of our customers, with only 15 minutes of clean-up per production run, that’s it. No more spending hours unclogging lines, no more throwing away cans that are underfilled. And because BoV separates product and propellant, the shelf life of viscous products is way longer too—no propellant mixing in, no product breaking down, which is another win for your bottom line.
I know there’s a lot of small details here, but that’s the thing about viscous products—they don’t follow the same rules as thin ones, so you need a machine that’s built to adapt, not just a regular BoV machine that’s been repurposed. We don’t just sell machines; we work with you to figure out what your product needs, whether it’s a super thick grease, a high-viscosity serum, a food-grade thick syrup, whatever. We’ve tested with everything from 5,000 cP to 100,000 cP products, so we know what works.
At the end of the day, the biggest advantage BoV has over regular aerosols for viscous products is that we don’t force the product to flow through a dip tube with propellant mixed in. We let the product stay in a flexible bag, only moving it when we need to fill, and use positive pressure from propellant outside the bag to push it out when dispensing. The filling process is all about making sure that product moves smoothly, no clogs, no air, consistent volume, and that’s what our machines are designed to do.
Aerosol Filling Line If you’re dealing with a viscous product that’s giving you headaches with your current filling setup, we can help. We don’t do hard sell tactics—just honest advice, test fills with your product, and a machine that’s built to work for your specific needs. Reach out to our team to chat through your requirements. We’re here to make filling viscous aerosols easy, not complicated.
References
- "Aerosol Technology: Properties, Behavior, and Measurement of Airborne Particles" by William C. Hinds
- "Bag-on-Valve Aerosol Systems: Principles and Applications" – Industrial Aerosol Association Technical Bulletin
- Viscosity Standards for Aerosol Filling Operations – ASTM International Standard D2983
- "Positive Displacement Pumps for High-Viscosity Fluids" – Pump Industry Magazine, 2022 Issue 3
Yangzhou Meida Filling Machinery Co., Ltd.
Yangzhou Meida Filling Machinery Co., Ltd. is well-known as one of the leading bag-on-valve aerosol filling machine manufacturers and suppliers in China. If you’re going to buy high quality bag-on-valve aerosol filling machine, welcome to get more information from our factory. For price consultation, contact us.
Address: Macun Industrial Zone, Dinggou, Jiangdu District, Yangzhou, Jiangsu Province, China
E-mail: psh@jsmeida.com
WebSite: https://www.meitarmachine.com/
