I recently encountered a P&ID drawing that contained the following information at the bottom of a 1,000 Gal storage tank:
1,000 gal, 6' ∅ x 5' HT

What does the ∅ mean in this description?
What is this information used to calculate the 1,000 gal?

I thought it meant diameter. But I went to school a long time ago!
That size sounds about right (http://wiki.answers.com/Q/How_many_cubic_feet_are_in_a_gallon).

Hope this helps,
WallyH