2023 Carbon Fiber tank sizes expanded and revised

[Humdinger]

This is an expanded and revised list of carbon fiber tank sizes. It includes the different units of measure commonly found on tank labels. The purpose of this list is to serve as a basis of comparison to buyers who may be unfamiliar with different units of measure. This will help to understand how much air each tank size holds at 4500 psi. The two most popular carbon fiber tanks are 6.8 liter and 9 liter. One upmanship is common in air gun vendor advertising so be an educated consumer before buying.

 

[TN_Yankee]

A good explanation of the math behind converting USA SCBA capacity to and from European capacity is from https://www.airgunnation.com/threads/scba-carbon-tanks.1178263/

The Metric rating of bottle volume and service pressure is different than the American methodology. So they are not comparable. The Metric system is wet volume with a pressure rating at 15 C temperature. The American system is compressed volume of atmospheric air at the bottle's service pressure at 70 F temperature. The formula to convert physical volume to the American rating is below:

References: Gay-Lussac's law of pressure and temperature (ideal gas), 1 liter = 28.32 ft3, 1 Bar= 14.696 PSI absolute, Z Factor = 1.0532 (air is not an ideal gas. It is a mixture of many gasses).

Wet volume in liters / 28.32 (ft3) x service pressure (PSI) / 14.696 (PSI (1 Bar)) x 1.0532 (Z Factor) = American service volume rating in ft3. More confusing is that the service pressure standard used for rating the effective volume is NOT the pressure rating of the bottle, but the Faber DOT US Spec rating for a steel bottle 3442 PSI. This also just happens to be about 235 Bar and the max service rating I choose to use. So, if you do the math a 12 liter bottle is rated at 100 ft3. So, the lesson offered boys and girls, is use only physical volume in your calculations, it is much less painful.