HP vs LP

[Sapper]

Are you refering to the comparison between an aluminum low pressure tank and a steel high pressure tank?

If so, the significant difference falls in the displacement/capacity ratio.
For example, an aluminum 80 cu. ft. tank (Catalina), at nominal pressure, holds approximately 77.4 cubic feet of air. The tank itself is 7.25" in diameter and approximately 26" long.

A high pressure steel tank (PST E7-80), at nominal pressure, holds approximately 80 cu. ft. of air. This tank is 8.00" in diameter and approximately 20" long.

So, the aluminum tank, with a displacement of approximately 1073 cubic inches holds 77.4 cf of gas while the hp steel tank with a displacement of approximately 1005 cubic inches holds 80 cubic feet of gas.

Therefore the aluminum tank holds .0721 cf per cubic inch while the steel tank holds .079 cf per cubic inch.

Also the inherent densities of the tanks are different resulting in a more negatively buoyant characteristic for the steel tank.

All of these factors go into resultant areas of required weight with different equipment configurations.

I am looking into steel tanks (120 cf)

 

[The Kraken]

In regard to my post that you quoted, please change the diameter of the E7-80 to 7.25" to review the resulting comparison.

Guess I need to go back and edit it.