Conn. Gen. Stat. § 43-41: Variations from marked weight.

When liquefied petroleum gas is sold or offered for sale by weight, variations at the rate of one pound per one hundred pounds plus or minus the marked net weight of the container are permitted in individual containers, but the average weight of not less than twelve containers shall not be less than the marked net weight of the container. When measured by meter, the meter and pertinent equipment must be such as to assure accurate measurement within plus or minus one per cent.