LP gas vaporization rates

[mbsmith]

I have three 1,000 gallon LP tanks that cannot supply my 1.2 million BTU/HR load demand under 0 to -10 degree F conditions. It is my intent to add as many 1,000 gallon tanks as needed to ensure adequate gas supply. The tanks will be manifolded with two-stage regulation. My only reference states that one half-full 1,000 gallon tank will supply an intermittent withdrawal rate of 525,000 BTU/HR if there is no tank frosting, and that this value should be reduced to 1/4 the intermittent rate for continuous loading. My questions are, 1) how do I evaluate tank frosting, 2) what constitutes continuous loading, and 3) how do I evaluate the tank level (fullness)?