(b) Refrigerated and semirefrigerated tanks shall be filled so that there is an outage of at least 2 percent of the volume of the tank at the temperature corresponding to the vapor pressure of the cargo at the safety relief valve setting. A reduction in the required outage may be permitted by the Commandant when warranted by special design considerations. Normally, then, the maximum volume to which a tank may be loaded is:

VL = 0.98drV ÷ dL

where: VL = Maximum volume to which tank may be loaded. V = Volume of tank. dr = Density of cargo at the temperature required for a cargo vapor pressure equal to the relief valve setting. dL = Density of cargo at the loading temperature and pressure.