Before I start a BIG word re safely, these cylinders (read the other posts) are potential killers, but if you are sensible and treat it with respect you shouldn't have anything to worry about.
There have been several threads recently about pressurised CO2, so I thought as I was setting up a new system I would show everyone how to do it cheaply using a fire extinguisher. So first you need a cylinder, these do vary in size but this 2kg cylinder is 23" tall (that is a DVD case next to it) and I got it on eBay for £22 including delivery from here
<a href="http://search.ebay.co.uk/_W0QQsassZ123safer4u" target="_blank">http://search.ebay.co.uk/_W0QQsassZ123safer4u</a>
Then you need a reg, again I got mine on eBay, you can spend as much as you like on a reg but these are cheap and I've found them to be excellent, with a very easy needle value built in.
<a href="http://stores.ebay.co.uk/Aquarianerversand...sQ3amesstQQtZkm" target="_blank">http://stores.ebay.co.uk/Aquarianerversand...sQ3amesstQQtZkm</a>
You'll need to remove the horn, which was easier to do than I had expected, just use a variable wrench. On a safety note it's a good idea to keep the safety pin in to prevent the lever from accidentally being squeezed whilst the horn is removed. Once the regulator is safely attached then remove the pin. If the extinguisher were to accidentally go off without the horn attached it can do a fair bit of harm as liquid CO2 comes out very fast. (Thanks James)
The reg didn't actually fit quite as snug as I had expected however its working find so no problems and this might be the same with all regs and cylinders to ensure a secure fit.
Tighten it well with the wrench, as if you don't it could cause you problems when you 'fire' the FE and we don't want people getting hurt now do we!
Now take it outside in order to 'fire' the FE to release the CO2. I was expecting an explosion or something when I did this, but I had tightened the reg nut well and a short hiss was all I got, good actually I don't want to lose my arms! The needle on the reg should go to around 50 bar and the other gauge is set using the larger black dial on the front of the reg. I don't think it really matters what you set this to, I just went for 1.5 bar for no reason at all!
You'll need to keep the handles closed to keep the CO2 flowing, I used gaffa tape.
Next check for leaks using soapy water
Now link it up to a bubble counter with check value to protect the reg from back flow.
The attach a diffuser. I'm a hugh fan of ceramic glass diffusers as they look the business and work a treat and really aren't that expensive. I love eBay and got mine from here
And some CO2 tubing
Then set the bubble rate and add to the tank
Once install, be sure to secure the cylinder carefully, either by chaining it to the wall or similar, anything to stop it being knocked over. In the words of James, if the reg gets knocked off the cylinder could take off, through the roof by the sounds on things! Better to be safe
This whole kit cost we around £70-75 quid and should last at least a year before I need a refill.
Hope that's of help to people
Edited by Themuleous, 30 April 2008 - 07:10 AM.