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 — and choosing the correct cartridge is critical.

In this guide, we’ll walk through the most common CO₂ cartridge sizes used for life vest inflation, how to identify the correct thread size, and the simple steps to replace an old cartridge with a new one.

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Understanding CO₂ Cartridge Sizes for Life Vests

Inflatable life vests use CO₂ cartridges that vary by gram weight and neck thread size. Each vest is designed for a specific cartridge size to achieve proper buoyancy.

Below are some of the most commonly used options:

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Life Vest CO₂ Cartridges Here

What does “cc” mean?

The “cc” rating refers to the approximate volume of CO₂ gas released when the cartridge is punctured.

• A 33g cartridge is commonly used in compact or lower-profile inflatable vests.

• A 38g cartridge provides enough gas for most standard adult life vests.

• A 45g cartridge releases more gas, making it ideal for heavier users, offshore conditions, or vests requiring higher buoyancy.

Always match the cartridge size specified by your vest manufacturer.

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Why Thread Size Matters (1/2" vs 3/8")

One of the most overlooked — yet critical — details when replacing a CO₂ cartridge is the neck thread size.

Common Thread Sizes:

• 3/8" threaded cartridges
  Often used with 33g cartridges and found in compact or manual-inflation vests.

• 1/2" threaded cartridges
  The most common size for adult inflatable life vests (33g, 38g, and 45g options).

• 5/8" threaded cartridges
  Found on some larger offshore or specialty vests.

? Pro Tip: Always check your existing cartridge or your vest’s rearming kit documentation before purchasing replacements. Even the correct gram size won’t work if the thread doesn’t match.

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How to Replace Your CO₂ Cartridge

Replacing a life vest CO₂ cartridge is straightforward — but proper installation is essential.

What You’ll Need:

• A compatible replacement CO₂ cartridge (correct gram weight and thread size)

• Replacement indicator or bobbin (if your vest uses one)

• Clean towel or cloth

Step-by-Step:

1. Check the vest’s status
   Ensure the vest hasn’t been deployed. If it has, fully deflate it before continuing.

2. Remove the old cartridge
   Unscrew the used cartridge and dispose of it properly.

3. Inspect the inflator mechanism
   Check for corrosion or debris and wipe clean if necessary.

4. Install the new cartridge
   Thread the cartridge in firmly by hand — snug, but not overtightened.

5. Replace indicator components (if applicable)
   Follow the vest manufacturer’s instructions.

6. Confirm readiness
   Most vests have a visual indicator showing green or “ready.”

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Final Safety Tips

• CO₂ cartridges are single-use — replace them after any inflation.

• Store cartridges in a cool, dry place to prevent corrosion.

• Always carry a spare cartridge or rearming kit onboard.

• Match both gram weight and thread size exactly as specified for your vest.

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Need Replacement CO₂ Cartridges?

At Red Rock Distribution, we stock a full range of threaded CO₂ cartridges, including:

• 33g cartridges (3/8" and 1/2" threads)

• 38g cartridges (1/2" thread)

• 45g cartridges (1/2" and 5/8" threads)

Perfect for inflatable life vests, rearming kits, and safety equipment — with bulk pricing and fast shipping available.