Hi Michael,

Thank you for the kind words.

Our volume calculator gives a volume of 19,036 US gallons for your tank as you said but 450 oil field barrels at 45 US gallons per barrel gives $450 \times 42 = 18,900$ gallons. I think the storage tank manufactures don't think the tanks will be completely full.

If you use our volume calculator for a cylinder with diameter 12 feet and depth 1 inch you get a volume of 70.5 US gallons. Thus to get 42 gallons, one oilfield barrel you need about $\frac{42}{70} = 0.6$ inches.

Lets do it more exactly. The volume of a cylinder is

\[\pi \; r^2 h \mbox{ cubic inches}\]

where $r$ is the radius in inches and $h$ is the height in inches. There are 231 cubic inches in a US gallon so if the volume is to be 42 US gallons then

\[42 \times 231 = \pi \; (6 \times 12)^2 h.\]

Solving for $h$ gives

\[h = \frac{42 \times 231}{\pi \; \times (6 \times 12)^2} = 0.596 \mbox{ inches.}\]

I hope this helps,
Penny