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How to Inspect and Rearm an Inflatable Life Jacket (PFD)

My auto-inflate PFD fired (or is overdue) — how do I inspect it and replace the CO2 cartridge?

An inflatable PFD is only Coast Guard "serviceable" when its CO2 cylinder is full, sealed, and screwed in tight, and its inflator trigger is loaded and indicating green. Rearming is a simple owner job: deflate and dry the bladder, replace the spent CO2 cylinder and (on auto models) the water-sensitive bobbin or capsule, then confirm both status indicators read green. The single most-missed point: you must buy the exact rearm kit for your specific inflator brand, model, and CO2 size — kits are not interchangeable, and a wrong cylinder or bobbin leaves you with a vest that won't fire when you go in the water.

ℹ️ Reference only: For general reference only. This guide does not guarantee any result — every home is different. Verify against your local building codes and a licensed professional before acting, especially for electrical, gas, plumbing, structural, or roof work.

💵 $15-$40 DIY for a standard manual or bobbin auto rearm kit; $25-$70 for a hydrostatic (e.g., Mustang HIT) rearm kit. A full replacement inflatable PFD runs roughly $90-$300 if the bladder fails. Professional inspection/service, where offered, is about $25-$75 plus parts. ⏱ 15-30 minutes hands-on to rearm, plus an overnight (16+ hour) leak-down test if you inspect the bladder. ● Use caution
Safety: This is life-safety gear — a vest that reads green but is wrong-rearmed can fail to inflate when you are face-down in the water. The biggest risks are mismatched parts (wrong CO2 size or wrong/expired auto element), an under-seated or cross-threaded cylinder that leaks down or won't pierce, and a leaking bladder that looks fine when packed. A CO2 cylinder is pressurized: keep it away from heat, don't puncture or incinerate it, and point the inflator away from your face during arming. An auto inflator will fire if it gets wet, so rearm in a dry area and store the vest dry and ventilated. Inflatable PFDs are approved only for people 16 and older and above a minimum weight (check the label) — never put a child in one; use a foam jacket instead. Always check that the PFD is USCG-approved (or your country's equivalent) and correctly sized for the wearer, and remember most inflatables are Type V that count toward the legal carriage requirement ONLY while actually worn — so wear it snug, don't just stow it.

Common causes

How to fix it

  1. Identify your exact inflator before buying anything. Read the label inside the vest for the brand and model (common ones: Mustang MIT/HIT, Onyx/Absolute A-24, Halkey-Roberts/United Moulders inflators) and note the CO2 cylinder size stamped on the old cylinder (e.g., 16g, 24g, 33g, 38g — most adult vest-style inflatables use 33g or larger to meet the ~22.5 lbf minimum buoyancy; 16g/24g are typical only of compact belt-pack units). Order the matching factory rearm kit — kits are model-specific and not interchangeable.
  2. Determine your trigger type. Manual-only = pull cord fires it. Automatic 'standard'/bobbin type = a water-soluble pill/bobbin fires it on contact with water (replace yearly or after firing, or by its printed date). Automatic 'hydrostatic' (e.g., Mustang HIT) = fires only under water pressure at about 4 in deep and the element is replaced about every 5 years. The kit you buy must match this type.
  3. Fully open the vest and unfold the bladder. If it inflated, manually deflate it: use the oral inflation tube, depress the small check valve inside the mouthpiece with the cap stem (do not jam in a sharp object that can score the seal), and gently squeeze all CO2 out. Never wring or roll hard against the seams.
  4. Inspect the bladder before rearming. Orally inflate it firm and leave it 16+ hours (overnight). If it stays firm, it holds air; if it softens, the bladder leaks and the vest must be retired, not rearmed. Also check fabric for abrasion, mildew, fading, and seam separation, and confirm any reflective tape, whistle, light, and straps/buckles are intact. Rinse salt off in fresh water and air-dry completely out of direct sun before reassembly.
  5. Unscrew and discard the spent CO2 cylinder. A fired cylinder has a pierced membrane in its neck — look at it so you know what a discharged one looks like. Cylinders are single-use; never reinstall a fired or partially discharged one. Dispose of it as scrap metal.
  6. Weigh the new cylinder if you want certainty. Each cylinder is stamped with a 'full' weight; a kitchen/postal scale confirms it's at or above that figure. Reject any cylinder with rust, dents, or a corroded/punctured cap.
  7. On auto models, replace the water-sensitive element. Remove the old bobbin/pill or hydrostatic capsule and fit the new one per the inflator's printed instructions, checking its date. This is the part people forget — a fresh CO2 with a dead/expired auto element gives a vest that won't auto-inflate.
  8. Hand-thread the new CO2 cylinder straight in, then snug it firm. It must be fully seated to pierce on firing, but do not overtighten with tools — finger-tight plus a small nudge is the spec for most inflators. Cross-threading or under-seating is a top cause of no-fire and slow leak-down.
  9. Confirm both status indicators read green. Most inflators have a green/red pin or window for the cylinder and a separate indicator for the auto element. Both must show green/armed. If either reads red, recheck that part — do not consider the vest serviceable until both are green.
  10. Repack per the diagram. Fold the bladder the factory way (wrong folds can pinch the bladder or block the cord), route the jerk cord so it hangs free and accessible, and close the cover/zipper. Log the service date and the auto-element replacement date so the next interval is tracked.
  11. Wear-test for fit. After any service, confirm the wearer is within the vest's rating: inflatable PFDs are USCG-approved only for users 16 years and older and above a minimum weight (commonly 80 lb — check the label), and are NOT child-rated, so put kids in an inherently buoyant (foam) jacket. Adjust the straps snug; an inflatable does nothing if worn loose or by someone outside its age/weight rating.

DIY or call a pro?

DIY for nearly everyone. Rearming and the visual/leak-down inspection are explicitly designed as owner tasks and are documented in every inflator manual. Hand the vest to a marine dealer or a manufacturer-authorized service center only if the bladder fails its overnight leak-down test, the inflator mechanism itself is damaged or won't hold green, the unit is a commercial/SOLAS jacket requiring certified annual service, or you simply want a professional inspection stamp. Commercial-use and many charter PFDs have mandatory periodic professional servicing requirements that recreational ones do not.

Tools & parts

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Based on: US Coast Guard (USCG) — PFD carriage, serviceability, and age/weight approval requirements; USCG Auxiliary — vessel safety checks and life jacket guidance; BoatUS Foundation for Boating Safety — inflatable PFD care and rearming; Mustang Survival — inflator/rearm kit instructions (MIT and HIT); Onyx / Absolute Outdoor — A-24 inflator rearming guidance; United States Power Squadrons (America's Boating Club) — PFD inspection guidance; ABYC — recreational boating safety standards

General marine-maintenance guidance, not a substitute for a qualified marine technician or surveyor. Boats and conditions vary; for fuel, electrical, fire, or structural issues — or anything safety-critical — consult a professional. Always follow your engine and equipment manuals.