Replacing fire extinguishers?

[Scooter]

Should you replace an old fire extinguisher even if it's still showing green?
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The directions are unclear:
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[Wayne Howard]

You might want to replace it if you sail near the CG station.

https://uscgboating.org/recreational-boaters/fire-extinguisher-faq.php

Q3. How do I tell if my fire extinguisher is expired?

A3.  If your disposable (non-rechargeable) fire extinguisher has the Underwriters Laboratories Inc. (UL) Trademark, a date of manufacture stamped on the bottle, and it is older than 12 years since the date, the extinguisher is considered expired and must be removed from service. Look for wording on the bottle stating, "This product must be removed from service within 12 years after date of manufacturing".

[Roland of Macatawa]

That appears to be a rechargeable fire extinguisher.
It notes recharging if the pressure is low.
So what is the approved lifetime of them?
1985 is 40 years old!
I'd probably replace it with a disposable one for which the rules are clear.

[Scooter]

Yeah, didn't expect to be taken seriously. It is rechargeable so I suppose I could keep using it, but no. That one came with the boat but it's been at on the hard at least 20 years. It's just the next thing that needs replacing before I splash.

[Riley Smith]

Save it as back-up. The dry chemicals really don't go bad, they compact. Shake it up to fluff up the powder in it. We'd use old expired ones in simulations and training. Never had one fail to work although they were commmercail/industrial units. We DID however have some blow out because of corrosion so there's that.

[noelH]

April 15th routine. Take down the bird feeders assuming the black bears have not. Change the water filter on well.  Give all the fire extinguishers a few taps with a plastic impact mallet and a good shake to dislodge any settled dry chemical.  Probably should check the expiration dates. Kiddie had a major recall a few years ago. Half a dozen fresh fire extinguishers!  But that was a few years ago. No expiration date found on them. Type B, size 1, 100psi. Did keep couple that were not replaced. Might give one a trial test and see if it delivers the noted 9.5-12 seconds of discharge. If it works fine. Great. No need to replace the recall replacement units.

[Riley Smith]

So in our fire training, we'd use the dry chemical extinguishers to put out a big living room sized tray of gasoline among other scenarios. It's lots harder than it first appears. Probably the worst mistake I'd see people make was to get too close to the fire. Blow a ripple in liquid gasoline and you can create a FIRESTORM! And the other was turning your back on that thing once it went out. IT WOULD REIGNITE!!!! Especially after the metal tray got hot from several exercises. Those little extinguishers don't do much more than check the mark on the legal requirement.

[Brian N.]

When I purchased the boat I stopped by a local retailer which specializes in fire safety equipment, representing several different manufactures. They put a tag on the extinguisher as to when it was due for service and recharge. I believe it was 12 years. Also, as Noel mentioned, invert the extinguisher and give it a couple of taps to loosen any compacted dry chemical

P.S.
Just checked the extinguisher, as I keep it inside during the winter. The tag is the date of most recent service. Of course it is over 12 years since the last service.