Dry chemical fire extinguishers EEK!


New member
My employer is a member of the Construction Association of Michigan, and I received a safety alert that should be of interest to all of us Stakers.

A man was killed when the cartridge type dry chemical exploded. When the cartridge was activated the corroded bottom of the extinguisher failed, propelling the extinguisher upwards striking him in the neck and chin.

While we do not have inspectors looking around in our home shops, I hope we do have extinguishers and that they are in "GOOD WORKING CONDITION". Dry chemical extinguishers are great at putting out shop fires but over years the contents can become an unusable lump and as this incident demonstrates corrosion can be deadly.

Please check your extinguishers!
When was the last time they were serviced?

The place you get your Oxy-Acetylene can usually help you with the service that might be required

Craig A

Re: Dry chemical extinguishers EEK!

I can't believe I never read this post before NOW but it honestly scared me.
Enough so that I renamed the thread and am posting so it gets some more attention.
I have never given a thought to that possiblity.
Those extinguishers are cheap enough that replacing them every now and then shouldn't break anyones' bank......


New member
Re: Dry chemical extinguishers EEK!

Over the years I have found them for sale in garage sales. I knew they could go bad. Often wonder why you would sell one that reads charged. I was told hitting the bottom with a rubber hammer does not help them or test them.

How do you dispose of old ones?
Re: Dry chemical extinguishers EEK!

Hey all,
I can only speak for my area, but all the local volunteer fire departments around here check, service, refill, and recharge extinguishers. It may be worth checking into.


New member
Darn 'stinguishers

I had a small kitchen fire years ago and had two dry chemical extinguishers. So I deployed the first one, which went pfff and a tiny trickle of powder came out, then it expired. So I quickly grabbed the other one which did the same thing. Negligible pressure in both.

Both of these had gauges that indicated they were charged.

I was also thinking recently about uses for old units, I have one that has a very nice looking aluminum formed vessel of about half a gallon capacity. Maybe a gas tank?:shrug:


Active member
Fire extinguishers should be inspected, and hydrostated, just like any pressure vessel. In case anyone does not know, the type of extinguisher that failed has a seperate CO2 cartridge that gets pierced to charge the extinguisher, I know in this area the railroad and some industrial users use them, they are probably a lot better for mobile use and in places where they temperature varies a lot, but they are not exempt from inspections-tho if they are in a truck or a remote spot, they often still get forgotten. As for the one in the kitchen and in your shop, they are worth the extra expense to get a real commercal type unit. The typical yearly inspection is just a visual exam to make sure they are still in pressure and not leaking, and they get a teardown, inspection, new valve, hydro, and recharge I think it was every 6 years?



New member
I may not be correct but thought that there are two types of dry chemical extinguishers. One holds pressure in the vessel with the chemicals all the time. When you open the valve the pressure and chemical are released. The other holds the chemicals in an unpressurized vessel and has a small cartrige that holds high pressure. When you open the valve the small cartrige pressurizes the large container forcing the chemicals out. The small home units tend to be the first type and the large commercial ones the second. Once again I may be wrong and hopefully someone who knows better will set me straight.



New member
In my area you only really see the presurized dry chem. Fire extinguishers need yearly checking to be up to NFPA codes this is why the tags are so important. Additionally, if the safety seal is broken you must always consider the extinguisher spent! I tend to travel to engine shows with CO2 and Dry chem because you can put out an engine fire with CO2 and not have all the mess. One just has to be wary of the wind speed and direction. The dry chem is for backup. Yes, every number of years they need to be dumped down, and hydrostatically tested like any other pressure vessle. You also want to treat all extinguishers with care; we wouldnt handle our nitrogen or welding bottles the way some people handle extinguishers, yet some are under the same pressures! I also use pressurized water in my work, but we dump them so regularly that we do our own refils and always carry a certified back up. I sent a number of them in for testing once and the company destroyed them all because there were slight dents in the base... grrrr. I had to point out to them that these were our day to day use ones and not for general certification.

My two cents


New member
I too love my refillable water extinguisher. I have it around whenever I'm using my torches, great first line of offense. Cheap and Easy to refill and if pressurized to 100 psi won't freeze right at 32 F (until you release pressure:bonk:).

Mrs Klaus, Do you smell smoke?



New member
Regarding the dry chemical in the extinguisher becoming a solid lump---in our monthly employee safety meetings this point was brought up, and the solution is very simple. Pick some day that you will remember each month (mine is the day my retirement check comes in), take the extinguisher and turn it upside-down and shake the living dickens out of it. If allowed to sit in one place very long the soda inside the shell will pack tighter than a bankers fist. Then when you really need it, the propellant will just fan the flames. I suspect that the extinguisher that blew the bottom out had been sitting on a damp floor and had rusted through. Put that fella on a bench or mount it in a bracket. Also, while you are shaking the soda loose, check that the dirt daubers haven't stopped the hose end up with mud.


New member
Please note that the type of Dry Chemical extinguisher that exploded was the larger commercial type it was not the smaller type you see in home or even normal business use.

This type can be easly identified by a sheet metal cover on the side of the extingusher bottle that contains cylinder about 2 inch around and from 8 to 10 inchs long, which is charge with carbon dioxide. In 30 years of working in the fire service the only place I recall seeing one was for our use on the fire engines.

That being said it is a good idea to have your extingusher check at least once a year - be safe!


New member
As a retired Firefighter/EMT I am a bit appalled that shop safety rules allow no yearly extinguisher inspections. Inspection of these is required in most FD districts. Their life span is 10 years at most in an office environment. They need renewal at five year increments, which includes pressure testing. Due to settlement, these need to be inverted and tapped gently on a MONTHLY basis! Any shop using any type of fire extinguisher needs to contract with a service that keeps the extinguishers up to date. Otherwise, the company is liable for the "buy once and hope" that kills.


New member
Any hand held fire extinguisher is supposed to be hung with the bottom at least 12" off the floor, we got cited by a local FD at one site, because they were only 6" off the floor. We passed the first year, got "whacked" the second year. The service company we had never suggested the height...


New member
Okay guys I am changing out all my Fire Extinquishers tomorrow. I and my father have been lucky and have never had to use one. Four of them have been hanging in two shops since Hector was a pup. The one in my 68 Chev 1 Ton has been there since 68. I do look at them periodically and they are all still in the green.


New member
That's why I have co2 units on my boat. No nasty powder residue and you know if it's going to work if charged.


This is the reason you should send them out to a proper service company once a year. We had one that the gauge said it was OK but when checked it had no charge in it. Also be sure there Hydotests are up to date.Normaly in this area it is 5 years maximum on a test.

Andrew Mackey

Dry Chemical fire extinguishers here in NJ, MUST be inspected yearly. Hydro tested every 5 years, replaced at 20, unless visual inspection reveals defect. extinguishers used on our fire trucks are discharged every 6 months, inspected and refilled.Extinguishers transported in a vehicle shuold be shaken up after every transport, to prevent 'packing'. packing is the effect vibration of transport has on the contents of the dry-chem extinguisher. it causes the powder to settle and become concentrated in a small area of the shell, rendering it useless. The same effect has been noted on the class D or 4 (purple K-for metals) extinguishers as well.

There have been many shell failures in soda-acid type extinguishers as well. If the acid container has been charged, the extinguisher MUST be fully discharged and the unit serviced immediately after use.

The charged water extinguishers also must face yearly inspection, with Hydro testing done every 5 years. They are generally replaced after 10 years of service, due to tank corrosion. Note - Water is NOT a good extinguisher for gas fires! It is meant for class A or 1 fires - paper and small wood fires only.

Any extinguisher with visible dents, rust or visible signs of corrosion, MUST be taken out of service immediately. The proper way to dispose of any extinguisher, is to discharge it amd either throw it away or recycle it. Most scrap yards want to see it either drilled or dis-assembled before they will accept it. DO NOT TRUST THE GUAGE! DO NOT drill or attempt dis-assembly of any shell/cylinder UNLESS you know for sure that the unit has discharged all contents, and has NO residual pressure. :rant:


Dick Graybill

Andrew are Soda Acid extinguishers still legal to use in your state? I know my company hasn't used them for I would guess 40 years,or more.Dick.