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Can a FE Co2 set up be dangerous?

R

rudirudi

Member
Joined
17 Jan 2012
Messages
60
Location
Ipswich
Hi
I have been running co2 on my tank since I set it up about 4 months ago,I use 500g re-fiillable bottles.I acquired a 2kg fire extinguisher from work for free so thought I would put it to use.I took it to the place where I get my bottles filled,the guy told me that the fire extinguisher should either have the dip tube removed,or operated upside down,(he removed the dip tube and filled the bottle for a tenner)if you do not do this you wil get liquid Co2 entering the regulator,this could be dangerous.I told him that to my knowledge most people just operate the FE upright with the dip tube in place,maybe I'm wrong.Has anyone experienced any problems.

Cheers

Rudi
 
What is the dip tube ? Ive certainly never heard of liquid CO2 entering the regulator and never had any problems. And there are probably hundreds of people using FE CO2 rigs, many of them on here. To answer your title question though, "Yes, of course they can" but no more so than a normal CO2 setup I would not have thought. Any pressurised system can be dangerous (including, and significantly more so, an unvented hot water cyclinder as found in many modern houses). Its all down to correct installation. I will be interested to hear if any of my "lerned" friends have any comments on the advice you were given above though :)
 
I had read the thread on here on how to put together a FE Co2 set up,I knew that a lot of people had used this system with no problems,I took the FE to get it filled,I told the guy at the FE company what I was using it for,he seemed quite shocked,he said the dip tube runs practically to the bottom of the FE,and when the lever is squeezed liquid Co2 is drawn from the bottom of the FE,he also said thatif it is used upside down,it would also work.I have looked on line and some people reccomend removing the dip tube,others say the liquid Co2 would turn gaseus on contact with the regulator.My knowledge on these things are very limited,just thought I would pass on something I was told by someone who seemed to know what he was talking about.

Cheers

Rudi
 
rudirudi said:
I had read the thread on here on how to put together a FE Co2 set up,I knew that a lot of people had used this system with no problems,I took the FE to get it filled,I told the guy at the FE company what I was using it for,he seemed quite shocked,he said the dip tube runs practically to the bottom of the FE,and when the lever is squeezed liquid Co2 is drawn from the bottom of the FE,he also said thatif it is used upside down,it would also work.I have looked on line and some people reccomend removing the dip tube,others say the liquid Co2 would turn gaseus on contact with the regulator.My knowledge on these things are very limited,just thought I would pass on something I was told by someone who seemed to know what he was talking about.

Cheers

Rudi
Click to expand...

Cheers for that Rudi. Its an interesting point. Sam (Themulfeus) or Dan Crawford are probably the guys to comment on it more. I always thought that liquid CO2 turned to gas as soon as it left the bottle myself, but the dip tube issue is interesting...
 
I guess any co2 set up if not correctly done can be dangerous, but I know of a few people who use the fe's for their source of co2 and one of them actually had the dip tube removed after he had read that it can pose problems but so far I've never heard of anyone having problems


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rudirudi said:
I had read the thread on here on how to put together a FE Co2 set up,I knew that a lot of people had used this system with no problems,I took the FE to get it filled,I told the guy at the FE company what I was using it for,he seemed quite shocked,he said the dip tube runs practically to the bottom of the FE,and when the lever is squeezed liquid Co2 is drawn from the bottom of the FE,he also said thatif it is used upside down,it would also work.I have looked on line and some people reccomend removing the dip tube,others say the liquid Co2 would turn gaseus on contact with the regulator.My knowledge on these things are very limited,just thought I would pass on something I was told by someone who seemed to know what he was talking about.
Click to expand...
Yes there are dip tubes in CO2 fire extinguishers, here is a picture I found earlier.
extinguisher.jpg


The FE when new will be about 2/3 full of liquid CO2. CO2 is liquid at room temperature due to the 55bar pressure. As you use the CO2 more liquid will evaporate to fill the space, the pressure remaining at 55bar, until all the liquid has gone. The space above liquid is required to limit the pressure if the FE gets hot. When it gets hot ie parcel shelf in a car in the sun, all the liquid turns to gas and pressure rises, but due to only filling 68% max (I think 68%) does not rise enough to burst the safety disk/over pressure valve.

Here is a video of CO2 fire extinguisher in a fire...all a bit boring, but as expected really.
http://dsc.discovery.com/tv-shows/mythbusters/videos/exploding-fire-extinguisher.htm

Anyway back on topic, we are using such a low rate of CO2 (ie we empty in 6 months, rather than 30seconds) that we will never see liquid coming out of the FE into the regulator.
 
co2q.jpg

This graph explains where the 68% max liquid fill of a CO2 fire extinguisher comes from.

If you move up from 70% of %fill to the 70F line you will see the pressure (on left) is 800psi, which in normal non US units is 55 bar @ 20C, which is what my FE beside my fish tank is. If I heat my FE to 120F/50C the pressure is still only 1500psi/100bar, still way below the 155bar/2200psi pressure release disk blowout pressure (2200psi/150bar).

However if I filled my tank to 100% at 70F/20C the pressure will still be 55bar/800psi, but if I heat my FE to 120F/50C the pressure will be nearly 2000psi/150bar getting dangerously close to burst disk/blowout pressure.
 
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