I'm thinking they should just be refilled with ether.
No really. Kidde will sell extinguishers with six year warranties, and I can't see that they expect the extinguisher to need annual servicing in each of those years. But, a fire captain giving a refresher class last week said all dry powder extinguishers in his experience needed to be replaced every year.
Because the cost of inspecting and refilling them was more than the cost of replacing them (handhelds, i.e. up to 5 or 10# size) and they were totally unreliable after one year.
He's probably discharged more of them than I've ever met, but condemning them all at one year....I don't know, I suspect Kidde knows more about extinguishers than he does.
You know, in most large cities there are con men with a great racket, they wander into offices and say "We're from the extinguisher company..." and then they swap 'em out and leave huge bills. The front desk rarely asks which company, or where the contract is. An old and common con, because people keep falling for it.
Ask your local USCG Aux or Power Squadron for a free safety inspection, or ask their senior inspector about fire extinguishers. And if no one cites you an actual law, an actual chapter and verse of code? Give 'em the ether filled extinguisher and tell them to use it up during a demonstration. (Is that evil? I'm trying hard to be evil, karma needs balancing.)
Also do bear in mind that for all safety equipment (extinguishers & pyros alike) you may be required to have xx pieces that are within date--but then you are also allowed to have whatever old outdated ones you want, also present on the boat. They do NOT have to meet any compliance regulations, because they are NOT part of the mandatory equipment.
So you can certainly keep the old ones as long as you have faith in them, regardless of needing (probably one or two?) newer dated ones.
FROM THE USCG at
"Fire Extinguisher Maintenance
Inspect extinguishers monthly to make sure that:
• Seals and tamper indicators are not broken or missing
• Pressure gauges or other indicators, if so equipped, read in
the operable range as described on the extinguisher
• There is no obvious physical damage, rust, corrosion,
leakage, or clogged nozzles
If the minimum weight is stated on the extinguisher label, weigh extinguishers
annually to check
Fire extinguishers that do not satisfy the above requirements or that
have been partially emptied must be replaced or taken to a qualified fire
extinguisher servicing company for recharge"
And there's no mention of anyone needing to sign you off on that.
AGAIN FROM THE USCG:
No mention of dating.
AND THE BEST OF ALL
Where they say "inspection" can be done by any idiot. Maintenance, if needed, should be done by certified idiots. And non-refillable extinguishers should follow the NFPA and be thrown out at TWELVE YEARS of age.
I suspect your surveyor mistook your boat for a commercial/mandatory service vessel, and should be sent to work in a shipbreaker's yard in Pakistan for a while.