measuring co2 level

[flopsy]

Hi-
Sorry not the most interesting topic choice! ;
but I'm signing off in a few days and need to still finish all the things on my 'i'll do it tomorrow' list-
Anyway, we got a co2 level measurer on this ship and i've marked all the levels off on the fixed co2 bottles; but now i'm kind of stuck doing the actual calculation bits of whether there is the right amount of co2 in the bottles. (up to 10% loss is okay).
I have a temperature/ density sheet which gives me e.g. Density of 0.675kg/ltr for a temperature of 27 degrees but I'm looking for a formula with which I can calculate what the liquid co2 level should be for a certain temperature (at normal filling) and what it would be at 10% less and then see if my level falls between the two.
This is the technical stuff:
Bottle: FIlling weight CO2 :45kg
Height of bottle: standard 150cm.
Circumference: 86cm;
Bottle can be filled with 67.5Litre (Water contents).
I tested something like 200 bottles over a week- and the temperatures were one day: 27, one day 25, one day 21 and one day 20. I know 27's a bit high but the captain was nagging me about getting it done.
Got to go on watch now- thanks if anyone can help me out with some sort of formula/calculation (not too complicated, i'm no dr. sheldon cooper)-
flopsy

[Clanky]

There are a few different ways to look at this.

The easiest is if you have the level when the bottles were full and just make sure that the level hasn’t dropped more than 10%. I would suggest that if more than half the bottles are at say 1.10m and that is the highest measurement that you have then that is the full level so as long as all the rest are above 0.99m then you are OK.

If you know the wall thickness of the bottles then you can calculate the volume using (((pi x (D-2t))^2)/4)x(h-t) where D is the bottle diameter, t is the wall thickness and h is the level and then multiply by the density to give mass, but that’s all a bit more complicated than it needs to be.

[flopsy]

Thanks Clanky;
the bottles are actually all around the 110cm mark so you're spot on. I'll also give that formula a go; although my head does hurt a bit just looking at it!
flopsy

[Chiefy]

I have a spear sheet some where for these, once you have the maths sorted, you put in the level and temp and it tells you ok or not.....will go for a rummage if you want

[flopsy]

Yes that would be great if you could do some rummaging- thanks Chiefy

[Chiefy]

https://www.dropbox.com/s/8i7h1pm2optqy35/CO%202.zip

try that and let me know how you go on.......MEMO get CD to alow xls attachements and >97kB

[flopsy]

Thank you so much Chiefy!!
Exactly what I was looking for; managed to do the whole thing in 30 mins rather than hours and now all ready to sign off- yay!

flopsy