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>While looking over the bouyancy characteristics  LP steel tanks I came
>across something that doesn't exactly make sense;
>
>According to OMS the difference in bouyancy for a 98cf from full to
>empty is about 8lbs (-7.73full/0empty)
>
>The numbers for a PST 95 are -4.75lbs full/-1.75lbs empty.
>
>What doesn't make sense is how can the PST change only 3lbs from full to
>empty when the actual air weighs at least 6lbs?
>
>Does anyone have any ifo on this?

Air weighs about 8 lbs/100 cu.ft.  (Source:  CRC Handbook of Chemistry and
Physics, 62nd edition, and a little calculator-punching)

The tank stretches (expands) as it is filled and relaxes (contracts) as it
empties.  The expansion causes it to displace SLIGHTLY more water, which
PARTIALLY offsets the weight of the air.

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