Replace your CO2 cylinder when it shows signs of use or damage, or on the schedule your PFD manufacturer recommends

A CO2 cylinder in an inflatable personal flotation device (PFD) is a sealed cartridge that holds pressurized gas. When you pull the ripcord or the PFD hits water, a needle pierces the cartridge and releases the gas to inflate the vest in seconds. Once that gas escapes—whether because you deployed the vest, tested it, or it leaked—the cylinder is empty and must be replaced. You cannot refill it yourself; you must buy a new one.

The timing depends on three things: whether you have actually used the cylinder, whether it shows physical damage, and what your manufacturer's instructions say. Most people who own an inflatable PFD never deploy it, so their cylinder sits unused for years. That is fine—an unused, undamaged cylinder can last the life of the vest. But if you have pulled the cord even once, or if you see rust, dents, or leaks, replacement is not optional.

Key Takeaways

  • A CO2 cylinder must be replaced when ready after deployment, even if only a small amount of gas escaped.
  • Inspect your cylinder every season for rust, dents, corrosion, or visible damage, and replace it if you find any.
  • Check your PFD manufacturer's instructions for their recommended replacement interval, which often ranges from one to three years even if unused.
  • Replacement cylinders are sold as cartridges by the PFD brand or by marine retailers and cost between $15 and $40 per cartridge.
  • Installation requires opening the PFD's cartridge chamber, removing the old cylinder, and inserting a new one—a task most owners can do in under five minutes.

After you deploy the vest, replace the cylinder when ready

If you have pulled the ripcord or the vest has auto-inflated in water, the cylinder is now empty. It has done its job and cannot be used again. You must replace it before you wear the vest again, because a second emergency will find you with no inflation mechanism.

Even a partial deployment counts. If you tested the vest by pulling the cord halfway, or if you heard a small hiss and realized the cylinder was leaking, replace it. Do not assume you can use the remaining gas. The cartridge is designed to empty completely in one event, and a partially used one will not reliably inflate the vest a second time.

Inspect the cylinder for rust, dents, and corrosion each season

Before you wear your PFD each year, open the cartridge chamber and look at the cylinder itself. A healthy cylinder is smooth, shiny, and free of discoloration. If you see rust (reddish-brown spots or flaking), white or green corrosion, deep dents, or punctures, the cylinder must be replaced. Corrosion weakens the metal and can cause slow leaks. Dents can prevent the needle from piercing the cartridge properly when you need it.

Rust and corrosion happen fastest in salt water environments or in damp storage. If you store your PFD in a garage, basement, or locker near water, inspect more often—every few months rather than once a year. If the cylinder looks clean and undamaged, you can leave it in place.

Follow your manufacturer's replacement timeline even if unused

Most PFD makers recommend replacing the CO2 cylinder on a schedule, typically every one to three years, regardless of whether you have used it. This is because the seal inside the cartridge can degrade over time, allowing slow gas leakage you may not notice. A cylinder that has sat for five years may not hold enough pressure to fully inflate the vest when you need it.

Check the instruction manual that came with your PFD or visit the manufacturer's website to find their recommendation. Common intervals are one year for commercial or professional use, two years for frequent recreational use, and three years for occasional use. If you cannot find the manual, contact the manufacturer directly with your PFD model number—they will tell you the safe interval for your vest.

Where to buy replacement cylinders and what they cost

Replacement cylinders are sold by the PFD manufacturer and by marine retailers. Search for your PFD brand name plus "CO2 cartridge" or "CO2 cylinder" to find the exact part. Most manufacturers sell them in packs of one or two. Prices vary by brand and cartridge size, but typically range from $15 to $40 per cartridge. Larger cylinders (which inflate bigger vests) cost more than smaller ones.

You can also find generic marine CO2 cartridges at boating supply stores, but always check that the size and threading match your PFD's chamber. Using the wrong size or type can damage the inflation mechanism or fail to inflate the vest. When in doubt, order the cartridge made by your PFD's manufacturer.

How to install a new cylinder yourself

Most PFD owners can replace the cylinder without tools. Open the cartridge chamber—usually a plastic or metal cap on the side or back of the vest—by unscrewing it by hand or with a coin. Remove the old cylinder by gently pulling it straight out. Wipe the inside of the chamber with a dry cloth to remove any debris or corrosion.

Insert the new cylinder straight into the chamber, making sure it seats fully. The needle inside the chamber should rest against the top of the cartridge. Screw the cap back on firmly but do not overtighten, which can crack the plastic or strip the threads. Once installed, do not pull the ripcord or test the vest—the cylinder is now live and will deploy if triggered.

When to ask a professional for help

If the cartridge chamber is stuck, corroded, or damaged, or if you cannot remove the old cylinder without force, stop and contact the manufacturer or a marine repair shop. Forcing a stuck cylinder can crack the chamber or damage the inflation mechanism, leaving you with a vest that cannot inflate at all.

If the vest itself leaks air (you hear a hiss from the fabric, not the cartridge), or if the ripcord is broken or stuck, those are separate repairs that may require professional service. A new cylinder will not fix those problems.

Frequently Asked Questions

Can I refill a CO2 cylinder instead of replacing it?

No. CO2 cartridges are sealed and designed for single use. They cannot be refilled at home or at a shop. You must buy a new cartridge. Some dive shops can refill larger scuba tanks, but not small PFD cartridges.

How long does a CO2 cylinder last if I never use it?

An unused, undamaged cylinder can last several years, but manufacturers typically recommend replacement every one to three years to may support the seal has not degraded. Check your PFD's manual for the specific timeline. If you store the vest in a dry place, it may last longer.

What happens if I deploy the vest and the cylinder does not inflate it?

This usually means the cylinder was already empty, damaged, or installed incorrectly. Inspect the cylinder for rust or dents before each season. Make sure it is seated fully in the chamber. If you have any doubt, replace the cylinder before wearing the vest again.

Do I need to replace the cylinder if I only partially pulled the ripcord?

Yes. Even a partial pull releases gas from the cartridge. Replace it before wearing the vest again. Do not assume the remaining gas will work in an emergency.

Can I store a PFD with an expired cylinder?

You can store it, but do not wear it in water. An expired or old cylinder may not inflate the vest fully when you need it. Replace the cylinder before using the PFD, even if you are just storing it for the season.