By waccobird 
Date 09-01-2011 16:38
Edited 09-01-2011 16:58
allabs
First Welcome to the American Welding Society Online Forum.
To help you quit wondering, Yes I know what the cubic foot capacity of an Argon bottle 5 1/2" in diameter is.
A formula can be found with a simple search on the internet.
Good Luck
And again Welcome to the Forum
Marshall
Lou I was suspecting you were a student getting easy answers till you updated your profile.
20 CF is what the 5.5"X15-18" bottle will hold
Gentlemen,
Allow me to make a comment to your instructions given to allabs.
What you have calculated is the internal volume of the argon cylinder. But the argon is stored in the cylinder at a pressure above atmospheric, so what you have calculated is the volume of argon presently contained in it.
But the volume of gases is always referred to at Standard conditions, which in the USA are atmospheric pressure and 60 ºF. The correction due to the ambient temperature, different from 60 ºF at which the cylinder is stored (say 40 ºF minimum to 90 º maximum), can be neglected because it is little, but the correction due to the different pressure from atmospheric can not.
To calculate the standard cubic feet (SCF) of argon contained into the cylinder, i.e., measured at atmospheric pressure and 60 ºF, the gas law must be applied.
Gas law: PV = nRT, where P is the absolute (i.e., not gage) pressure; V is the volume, n are the number of mols, R is the gas universal constant and T is the absolute (i.e., not F or C) temperature.
I stress: gas volumes are always referred to at standards conditions, always atmospheric pressure and 60 ºF in USA and zero ºC in ISO countries.
Giovanni S. Crisi
Sao Paulo - Brazil
Bravisimmo Giovanii. Bravo, bravo. Ah, the stray, unnaccounted for law of physics, so easily overlooked, forgotten, counter intuitive, demanding of logic and hard fact, defied in ignorance, mocked in wishfull thinking effigy like a 20 minute boiled egg still raw, inedible and revolting. Clear thought is like overcoming gravity.
An alternative:
P1 x V1 / T1 = P2 x V2 / T2
P1 is the absolute pressure of the cylinder in the filled condition
V1 is the volume of the cylinder (covert all cylinder dimensions to feet, i.e., 6 inches = 0.5 ft, 8 inches = 0.667 feet, etc. to get your volume in terms of cubic feet)
T1 is the absolute temperature
P2 is the pressure when the gas is released, i.e., 1 bar
V2 is the volume of gas at sea level (29 psi approximately)
T2 is still the temperature once the gas is released, i.e., there is no change
You can rewrite the equation as:
P1 x V1 = P2 x V2 because the initial temperature is the same as the final temperature, so the terms T1 and T2 cancel each other
You know the initial pressure (in terms of absolute pressure) and you can calculate the volume of the cylinder while it is pressurized. Use the formula L x 3.1416 x D x D / 4
You know the final pressure once the gas is released from the cylinder, i.e., absolute pressure at 1 atmosphere (29 psi is close enough for most work)
So you have:
Solve for V2 = P1 x (L x D x D/4 x 3.1416) / 29
This should give you a close approximation of the volume of gas (in terms of cubic inches unless you convert all the dimensions to feet when calculating the volume of the cylinder) at standard temperature (68 degrees F) and at one atmosphere at sea level.
Good luck - Al
I'm just gonna cal Al and say:
"how much is in this"?
....you may want to multiply your answer by % of volume filled(possibly 85%)...ie safety factor for the filling station
