Bob
The two charts don ‘t agree.
Re.9L Great White as one example - The first says the 9L does have 88 cubic feet at 4500psi. Yours says 97 cu feet at 4500 psi.
Which is correct?
Tom
Upvote 0
Carbon fiber tank size comparison chart
- Thread starter Humdinger
- Start date
Bob
The two charts don ‘t agree.
Re.9L Great White as one example - The first says the 9L does have 88 cubic feet at 4500psi. Yours says 97 cu feet at 4500 psi.
Which is correct?
Tom
Well, I'm going to go with mine, since the chart I made used simple math formulas, not data gleaned from the internet.
Upvote 0
Bob
I found this post and perhaps this explains the discrepancy. Take a look.
Carbon Fiber Air Tank Liter to Cubic Feet Conversion
A friend of mine asked me the other day about carbon fiber air tanks on eBay and how some of this type of HPA tanks that are made here in the USA are measured in cubic feet and not liters. Well I didn’t have a clue what to tell him so I told him I would get back to him when I had the answer. It...
www.airgunnation.com It appears the discrepancy ( 97/98 cu ft vs. 86 cu ft ) is due to how you calculate the PSI for 300 BAR. The formula yields a different result using 4351 PSI as 300 BAR vs. when the formula uses 4000 psi for 300 BAR. The post suggests the Chinese chart uses 4000 psi for safety reasons vs. 4351 psi
Technically, 4351 psi equals 300 BAR which yields the higher value at 94.07 cu feet.
So, If this post and formula logic is correct, it appears to me that the Manufacturer can quote the higher spec using 4351 psi in the formula.
Upvote 0
Well, as I stated above, it's simple math. Disregarding the heat factor, of course. Yes, 4351 psi is 299.99 bar. Always has been, always be. (I cannot speak to what some company from China claims it to be)Bob
I found this post and perhaps this explains the discrepancy. Take a look.
Carbon Fiber Air Tank Liter to Cubic Feet Conversion
A friend of mine asked me the other day about carbon fiber air tanks on eBay and how some of this type of HPA tanks that are made here in the USA are measured in cubic feet and not liters. Well I didn’t have a clue what to tell him so I told him I would get back to him when I had the answer. It...
It appears the discrepancy ( 97/98 cu ft vs. 86 cu ft ) is due to how you calculate the PSI for 300 BAR. The formula yields a different result using 4351 PSI as 300 BAR vs. when the formula uses 4000 psi for 300 BAR. The post suggests the Chinese chart uses 4000 psi for safety reasons vs. 4351 psi
Technically, 4351 psi equals 300 BAR which yields the higher value at 94.07 cu feet.
So, If this post and formula logic is correct, it appears to me that the Manufacturer can quote the higher spec using 4351 psi in the formula.
Also, Boyle's law has been around since the mid-1600s. Can't really argue with them maffs. And the math in your quoted post is as accurate as mine is, but we are talking about 4500 psi, or 310.26 bar, and THAT is what leads us to 97 cu ft as opposed to 88.
To be clear, a 9L/550 cu in tank filled to 4,070 PSI (280.6 bar) will hold 88 cu ft, whereas filling it to 4500 psi (310.3 bar) will result in an air volume of 97 cu ft.
(And that firman's rating... we need to just drop that from our vernacular, as it is useless, even for firemen; anyone should be able to deduce that a 110 lb female firefighter won't draw as much air as a 210 lb male firefighter. And BOTH of those will draw more air, thereby reducing the time a tank lasts, when they are stressed and exerting themselves.)
Thanks for pointing out that post!
Upvote 0
