Dry powder fire extinguisher

[Burnerman]

I have a 5kg one of these in my garage......it’s a Chubb, no date but no rust or damage.
The pressure gauge is reading 0. The gauge scale goes - 150 +.
There’s a schrader valve on the side of the neck, and when I depress it the powder spurts out, so its clearly still full.
The burning (!) question is.....can I repressurise it myself, or is the propelling gas something inert such as nitrogen?
Any knowledge / advice appreciated!
John

 

[Stivino]

The propellant is normally Carbon dioxide and it's contained in a cylinder that hangs vertically from the handle on the inside, obviously .
It is sealed, and the seal is broken when you strike the button or squeeze the handle. With dry powder, you have to shake them periodically to prevent the powder from compacting. Otherwise they won't work when you need them.
In a previous life, I used to strip them down, check the CO2 cylinder was intact, weigh it, weigh the powder and re-build them.
I'm not sure I understand the extinguisher you are describing but, if you are in any doubt about it, they are as cheap as chips.
HTH

 

[HERTS P&D]

John, why take the risk. Your advice to anyone else would be to replace it for piece of mind.

So John, buy a new one.

Andy

 

[Burnerman]

Many thanks for the replies gents, appreciated!
I was a bit confused because Mr. Google said the propelling gas was either dry air or oxygen free nitrogen (?)
I’ll give it the hoy!
John

 

[Burnerman]

The propellant is normally Carbon dioxide and it's contained in a cylinder that hangs vertically from the handle on the inside, obviously .
It is sealed, and the seal is broken when you strike the button or squeeze the handle. With dry powder, you have to shake them periodically to prevent the powder from compacting. Otherwise they won't work when you need them.
In a previous life, I used to strip them down, check the CO2 cylinder was intact, weigh it, weigh the powder and re-build them.
I'm not sure I understand the extinguisher you are describing but, if you are in any doubt about it, they are as cheap as chips.
HTH

What about the schraeder valve on the side, Stivino?
John

 

[Stivino]

I don't know about the valve on the side, I've never come across that type.
I can only think that it is to pressurise the container. Maybe what you have is constantly under pressure, unlike the type I used to deal with?

 

[Burnerman]

Definitely a schraeder valve, I pressed the centre tit and powder was there.
So, I reckon as it has a pressure gauge then it must be constantly under pressure - therefore if I was to stick my air line on the thing the gauge may move to the 150 mark.
I don’t have any problem with replacing the thing but if it is useable it may as well stay!
John

 

[Stivino]

I imagine that it won't be air that is used to pressurise it, not with it being a fire puter outer.
EDIT: I just watched a guy on youtube topping one up with air, so what do I know?
I would have thought it would have been an inert gas as air would feed the fire?

 

[Burnerman]

Hence my post #4!
I guess all it has to do is to force the powder out though and once that has gone its time for a refill.
John

 

[bernardgreen]

Propellent in standard dry powder extinguishers is compressed nitrogen,

 

[Stivino]

Propellent in standard dry powder extinguishers is compressed nitrogen,

It was Carbon dioxide in the ones that we did.

 

[conny]

@Burnerman, John I'm probably trying to teach you how to suck eggs but if you are going to dump it please release the pressure, (and hence powder), before you do. Only needs some nerd to find it and jokingly point it at a mate for someone to potentially get seriously hurt if it's still full or even partially loaded.

 

[Burnerman]

Thanks for that conny
Here’s an update.
I’ve pressurised the extinguisher with dry air (recommended as a propellant) up to 130 psi - as high as my compressor will go. The gauge on the extinguisher has risen towards the operating zone (150 psi) but obviously is a little low.
Anyway, its back on it’s bracket for now, and when I replace it I’ll discharge it completely.
The powder is incredibly fine - I’ve no idea what it is chemically but for sure it has a funny taste.....got a swift blast whilst faffing with it but no adverse effects!
Regards
John

 

[conny]

Thanks for that conny
Here’s an update.
I’ve pressurised the extinguisher with dry air (recommended as a propellant) up to 130 psi - as high as my compressor will go. The gauge on the extinguisher has risen towards the operating zone (150 psi) but obviously is a little low.
Anyway, its back on it’s bracket for now, and when I replace it I’ll discharge it completely.
The powder is incredibly fine - I’ve no idea what it is chemically but for sure it has a funny taste.....got a swift blast whilst faffing with it but no adverse effects!
Regards
John

No flying elephants or thinking you could fly? Must be a cheap one from Aldi.

 

[bernardgreen]

The propellant is normally Carbon dioxide

• Dry powder extinguishers are tanks of dry powder with compressed nitrogen as the propellant. In extinguishers like this, it's the composition of the chemical (rather than the mechanical design of the extinguisher) that really counts The powder is a specially designed mixture that absorbs heat, melts, and coats the fuel, stopping it from making flammable vapors and blocking out oxygen, so it's helping to tackle two sides of the fire triangle at once. The most widely used powder in extinguishers is monoammonium phosphate; other powder ingredients include the metal alkali salts sodium bicarbonate (baking soda) and potassium bicarbonate (similar to sodium bicarbonate), though these are less effective on things like wood and paper fires.

SOURCE