Which CO2 cartridge size is right for a 150N life jacket?

If the CO2 cartridge in your life jacket doesn’t match its buoyancy rating, it’s like buying a parachute that might not open. You wouldn’t risk it, right?

A 150N inflatable life jacket typically requires a 33g CO2 cartridge with a 1/2″ UNF thread. This size provides sufficient gas volume to inflate the bladder fully for standard adult buoyancy.

Many first-time buyers get confused when they see “150N” on the life jacket label. They wonder if it relates to weight, gas pressure, or maybe even body size. And that’s where mistakes start to happen. Let’s break this down so you’ll never choose the wrong cartridge again.

What does “150N” actually mean for a life jacket?

“150N” is not about your body weight. It refers to the buoyancy force the jacket can provide. Think of it as the jacket’s ability to lift weight in water — 150 newtons equals roughly 15 kilograms of lifting force. That’s enough to keep a full-grown adult safely afloat, even if unconscious, in rough waters.

150N refers to the buoyancy force a life jacket provides—enough to keep an average adult afloat in rough waters, even when unconscious. It’s a safety classification, not the person’s weight.

150N ≠ 150kg

This is a common misconception. Newtons measure force, not mass. A 150N life jacket is designed for ocean conditions and is suitable for most offshore activities.

How buoyancy determines cartridge size

Here’s a quick breakdown:

If you’re using a 150N jacket, 33g is the sweet spot.

Why is 33g the most common size for 150N life jackets?

Not too little, not too much. 33g is just right. That’s the size that can displace enough gas to fully inflate the bladder of a 150N vest. If you go smaller, the jacket won’t inflate properly. Go bigger, and you risk damaging the valve or even triggering an unsafe pressure spike.

33g cartridges deliver the right volume of CO2 to inflate a 150N life jacket fully. Using a smaller cartridge risks under-inflation, while using an oversized one may cause failure.

At Alizeemetal, our 33g CO2 cartridges are filled to precise specifications — 99.99% pure CO2, typically pressurized to 60 bar (870 psi), with 1/2” UNF threading that fits most inflators on the market.

Alizeemetal factory-grade features:

• 100% leak-tested before shipping
• Supports OEM branding (sticker, laser, or silk screen)
• CE & ISO compliant
• Available in bulk (MOQ 5000pcs)

How to know if your current cartridge fits your life jacket?

You already have a life jacket, but you’re unsure if the spare cartridge matches? Don’t guess. Check these three things:

Check three points: the cartridge weight (grams), the thread size (e.g., 1/2” UNF), and whether the inflation system is automatic or manual. Mismatches may cause malfunction.

Step 1: Check the cartridge label

Most cartridges are engraved or labeled with their weight (e.g., 33g) and thread type. Look for “UNF 1/2” or “⅝ UNF” depending on your inflator.

Step 2: Identify the inflation system

• Automatic (activates on water contact)
• Manual (pull cord)
• Hybrid (dual system)

Step 3: Rearm correctly

Always rearm with the correct cartridge + bobbin kit. Most manufacturers offer complete “rearming kits” for specific models. For reference, Mustang Survival’s rearming guide explains how to safely match your life jacket with the correct components.

Can you customize CO2 cartridges for 150N jackets?

Absolutely. Many of our customers are B2B suppliers and marine gear brands that need consistent quality with custom branding. We support customization from product design all the way to packaging.

Yes. We offer private-label 33g CO2 cartridges compatible with 150N life jackets. Options include logo silk-screening, packaging customization, and OEM filling certifications.

What can be customized?

If you’re building your own marine safety product line, having your logo on every cartridge boosts brand trust and traceability.

Conclusion

33g is the right choice for 150N life jackets—but not just any 33g. Be sure it matches your thread size and inflation system.