Except as otherwise provided in the subchapter, liquids and liquefied gases in a bulk packaging have to be loaded so that some outage is left. How much, and judged at what temperature?

Explanation

Liquids and liquefied gases must be loaded so that outage is at least five percent of the total capacity of the cargo tank, portable tank, tank car (including dome capacity), multi-unit tank car tank, or any compartment thereof for materials poisonous by inhalation, and at least one percent for all other materials, measured at reference temperatures of 46 C (115 F) for a noninsulated tank, 43 C (110 F) for a tank car with a qualifying thermal protection system, and 41 C (105 F) for an insulated tank. Two qualifiers travel with the figures and change what the rule reaches: it opens except as otherwise provided in the subchapter, so a more specific provision can displace it, and it governs hazardous materials in bulk packagings rather than liquid cargo generally. The reference temperatures are the point of the rule, since outage exists to leave room for the product to expand as it warms. The wrong options each remove one of those elements, flattening the two percentages into a single larger one, dropping the poisonous-by-inhalation distinction, or replacing the fixed reference temperatures with a judgment call.

Source: 49 CFR 173.24b(a)(1)