Whether you’re heading out for a day of fishing, kayaking, or offshore boating, having a properly charged inflatable life vest can mean the difference between safety and disaster. These vests rely on CO₂ cartridges to automatically or manually inflate when needed. But not all cartridges are created equal.
In this guide, we’ll walk you through the most common sizes used for life vest inflation, how to identify what cartridge you need, and the simple steps to replace your old cartridge with a new one.
Understanding CO₂ Cartridge Sizes for Life Vests
The most commonly used CO₂ cartridges in inflatable life vests vary by volume and thread size. Two of the most standard sizes are:
| Cartridge Size | Volume (Approx.) | Neck Thread Size | Typical Use |
|---|---|---|---|
| 38 gram | ~50cc | 1/2" | General-use adult vests |
| 45 gram | ~60cc | 1/2" or 5/8" | Larger vests, offshore use |
What does “50cc” or “60cc” mean?
The “cc” refers to the approximate volume of CO₂ gas released when the cartridge is punctured. A 38g cartridge releases about 50cc of gas, which is sufficient to inflate most standard adult life vests. A 45g cartridge releases more, making it better suited for higher buoyancy needs or larger-sized vests.
Why Neck Size Matters
When replacing a cartridge, one of the most overlooked — but critical — details is the neck thread size. Most vests are compatible with a 1/2" threaded cartridge, but some larger or specialty vests may require a 5/8" threaded neck.
? Pro Tip: Always check your old cartridge or the vest’s rearming kit documentation for thread size compatibility before buying a replacement.
How to Replace Your CO₂ Cartridge
Replacing a CO₂ cartridge is quick and easy — just make sure to follow the correct steps to ensure safety and functionality.
✅ What You’ll Need:
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A compatible replacement CO₂ cartridge (match the gram weight and thread size)
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A replacement indicator (if your vest uses one)
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Clean towel or cloth
? Step-by-Step Instructions:
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Check the vest’s status
Ensure the vest hasn’t been deployed. If it has been inflated, manually deflate it completely before proceeding. -
Remove the old cartridge
Unscrew the used CO₂ cartridge from the inflator mechanism. Be sure to dispose of it properly. -
Inspect the inflator
Look for any corrosion or damage inside the inflator. Wipe it clean with a dry cloth. -
Install the new cartridge
Screw the new CO₂ cartridge into the inflator firmly, but don’t overtighten. Ensure it’s secure. -
Replace the indicator (if applicable)
Some automatic vests have a visual indicator or dissolvable bobbin. Replace these parts according to your vest’s rearming instructions. -
Test the vest’s readiness
Most vests have a readiness window or indicator. Make sure it shows green or “ready.”
Final Tips
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Always use CO₂ cartridges approved by your vest manufacturer when possible.
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Store cartridges in a cool, dry place to prevent corrosion.
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Replace cartridges after each inflation — they are single-use only.
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Keep an extra cartridge and rearming kit onboard if you're out for long trips.
Need Replacement Cartridges?
At Red Rock Distribution, we carry a range of threaded CO₂ cartridges including 38g and 45g options with both 1/2" and 5/8" necks — perfect for rearming inflatable life vests. Bulk pricing and fast shipping available.