FraserNZ Posted August 21, 2011 Report Share Posted August 21, 2011 I guess this question is a bit like asking how long a peice of string is... but, anyway... The reason I ask as is that I purchased a 7.5kg bottle which I hooked upto my 300L. I adjusted it to the recomended PH&KH level as per the reference chart that is on the internet. Unfortunately I had some trouble reading my bubble counter, however, I think it was running at around 2 bubbles per second. The problem is I only got just over a month out of this tank at this rate?? I thought a tank this size would normally last 10-12 months??! Any advice would be great cheers! PS, I have the reg setup on a timer so is only running for 8 hours a day. Quote Link to comment Share on other sites More sharing options...
Jennifer Posted August 21, 2011 Report Share Posted August 21, 2011 For me a 5kg cylinder lasts about 3-4 months on a 400L tank, running 8 hours a day. Quote Link to comment Share on other sites More sharing options...
amtiskaw Posted August 22, 2011 Report Share Posted August 22, 2011 I'd spray all the fittings with soapy water and look for bubbles indicating a leak. Quote Link to comment Share on other sites More sharing options...
FraserNZ Posted August 22, 2011 Author Report Share Posted August 22, 2011 I'd spray all the fittings with soapy water and look for bubbles indicating a leak. Yeah I was thinking that. I was really hoping to get at least 6 months out of it Quote Link to comment Share on other sites More sharing options...
phoenix44 Posted August 22, 2011 Report Share Posted August 22, 2011 Sounds like it could be leaking. I have an 8kg bottle and I'd be pretty disappointed if it lasted less than 6 months. Quote Link to comment Share on other sites More sharing options...
FraserNZ Posted August 22, 2011 Author Report Share Posted August 22, 2011 Sounds like it could be leaking. I have an 8kg bottle and I'd be pretty disappointed if it lasted less than 6 months. I talked to one of the guys at HFF and he told me 2-3 months was normal for that size bottle... (purchased from them) the reg only ever had a reading of 50 which was about a third of the way round? Is it possible that it just had a rubbish fill? Quote Link to comment Share on other sites More sharing options...
Jennifer Posted August 23, 2011 Report Share Posted August 23, 2011 Most cylinders have two dials. The dial in the line closest to the cylinder (usually showing around 1000 psi) is the pressure in the cylinder (and thus a measure of how full the cylinder is). The other dial is the pressure coming out of the valve nozzle (at the junction where the tubing meetings the metal valve) ie, the delivery pressure, and is usually around 50 psi. A good regulator should maintain that pressure until the cylinder is completely empty, and then of course that value drops as the gas runs out right at the very end. It's like a set point value above which the pressure wont go in an ideal world (but of course that 'dumping' phenomena of cylinders is due to something else related to the setpoint trying to maintain that deliver pressure in the face of a lower cylinder pressure at which point it opens wider to try and keep that setpoint). Quote Link to comment Share on other sites More sharing options...
Warren Posted August 23, 2011 Report Share Posted August 23, 2011 Unfortunately the pressure in a CO2 bottle is not a good measure of how full it is. When CO2 is compressed it sits at the bottom of the bottle as a liquid and has a gas layer above the liquid. Until all the liquid phase of the CO2 is gone (basically empty) the pressure stays fairly steady at 1000psi and then very quickly drops at the end when only gas is left. You either have a leak or partial fill. My 6.8kg would last about 8-9 months. Quote Link to comment Share on other sites More sharing options...
Jennifer Posted August 24, 2011 Report Share Posted August 24, 2011 True! We should be calling them 'tanks' and not 'cylinders.' :smln: I should have mentioned that the vapor pressure of the CO2 in the tank will change according to the temperature as well. At very low temperatures it may get down as low as 600psi and if it is around 25 degrees C the pressure will read closer to 1000psi. Quote Link to comment Share on other sites More sharing options...
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