# What pressure should I replace co2 cylinder?



## Matt Warner (5 Dec 2011)

Hi all, I was just wondering what pressure you replace your co2 bottles at. I have a 500g cylinder which reads about 900psi when refilled and then drops off gradually after a couple of months. I want to get my money's worth out of these bottles so was wondering what the minimum pressure is that I should get a new one.
Cheers


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## Alastair (6 Dec 2011)

I just go off what my co2 cylinder weighs mate. I know empty it's 15 kg and full is 22kg so periodically weigh it. Other than that a few days before it gets empty the pressure drops from 55 to just below 50.


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## Matt Warner (6 Dec 2011)

Thanks Alastair. My pressure gauge also seems to change depending on temperature which I have read is normal. The pressure is higher when it is warmer. I probably could of got another few weeks out of my cylinder until the o ring perished on the bottle and I lost a load of gas. Annoying. I'm going to go up the FE route soon anyway I just need a regulator to fit one. Do you know if any modifications need to be done to the FE for it to work. I have heard that there is a tube inside which might have to be remove.
Cheers


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## Alastair (6 Dec 2011)

Hmmm not sure about modifications to it, do you mean to make your reg fit? 
I've heard about the tube inside also, but as I have never used a FE I don't know mate and wouldnt like to say. I'm sure if you pop up something in the co2 section asking, then soneone may know. Lots of people use them on here. I just opted for a big cylinder ha ha. 
Are you looking for second hand reg?


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## spyder (6 Dec 2011)

I believe the tube is to assist rapid dumping when used as an extinguisher so the contents can be dumped in seconds. Has no effect with a reg and drip feeding the gas.


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## Matt Warner (6 Dec 2011)

Thanks spyder. I really want to set up an FE but just worry about blowing myself up!


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## ashcarter89 (6 Dec 2011)

lol i was the same when i used my first fire extingusher i took it all out to the garden closed my eyes and slowly pushed on the handle , all to find out that nothing actually happens just a tiny noise while the reg goes to pressure haha. But no its fine to run FE's . The rate in which we run the gas means that by the time that the liquid co2 gets to the reg its heated up enough to become gas again , meaning no harm to the reg


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## Dan-CR4 (6 Dec 2011)

Matty1983 said:
			
		

> Thanks spyder. I really want to set up an FE but just worry about blowing myself up!



I was thinking the exact same thing when I did mine back in Febuary  , I am now on my second bottle and all has been fine so far.


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## PeteA (6 Dec 2011)

Dan-CR4 said:
			
		

> Matty1983 said:
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I did it on Saturday - really intimidating but actually a bit of an anti-climax.  Just be sensible and point things away from you when you press the handle.


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## spyder (6 Dec 2011)

Was typing at work so, consider 2kg co2 fire extinguisher is discharged in around 12-15 seconds, that's how fast it gets dumped. If you've never seen one go off then I'm sure there's plenty of clips on youtube.   

Slightly off topic but one of my techs spotted a bin fire, well a bit of smoke, grabbed a co2 and took aim into the hole in the side, pulled the trigger and the lid flew off. I would of just carried the bin outside.   

Back on topic, I've not replaced mine yet. Got a 3kg to get filled and considering grabbing a FE or another cylinder so I won't have to panic when the time comes.


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## Alastair (6 Dec 2011)

I always keep a spare now. Two 4 foot cylinders in my living room now ha ha


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## Matt Warner (6 Dec 2011)

Well I'm glad it's not just me who is a but intimidated by it! I guess if you treat it with respect and don't squeeze the levers til the regulator is tight then there shouldn't be a problem.


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## gmartins (7 Dec 2011)

Hey,

the regulator measures the pressure of CO2 gas inside the cylinder. However, inside the cylinder CO2 is present in as gas and liquid forms. The regulator will only tell us the pressure of the gas (not the liquid). What happens is that as CO2 is consumed, the liquid converts to gas so that the overall pressure is maintained. Hence, our pressure gauge in the regulator is always fixed (usually around 50-60 bar). Yes there are tiny fluctuations according to room temperature. When the liquid CO2 finishes we are now left only with the gasous form. As we consume it the pressure decreases and this is the only time when we can the pressure decreasing in the pressure gauge. It will usually last 1-2 days depending on consumption rate, size of bottle, etc....

Hope this makes things a bit clearer.

Cheers,

GM


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