(a) When transported in cargo transport units, the cargo transport units must provide an adequate exchange of air in the unit. This adequate exchange of air may be accomplished by utilizing a ventilated container, an open-top container, or a container in one door off operation. When cargo transport units with venting devices are used these devices should be kept clear and operable. If mechanical devices are used for ventilation, they must be explosion-proof.
CFR 49-176.907-2013 history
2013CFR 49-176.907-2013 Transportation. Part176:Carriage by vessel. Section176.907:Polymeric Beads and Plastic Molding Compounds.