A hold contains a very large volume of air. Any air brought in by ventilators at any instant is very small compared to the volume of the hold. If the temperature of the air in the hold is low, the incoming air will be cooled and, if the incoming air is cooled below its dew point, it will give off moisture. This will condense as sweat on cargo and in the steel parts of the hold and is liable to cause damage to cargo. It is therefore essential to compare the temperature of air in the hold with the dew point of the outside air.
If hold temperature is less than dew point of outside air, restrict ventilation.
If hold temperature is moLre than dew point of outside air, ventilate freely.