Blockquote In order to transport Ln2 the Dewar must have a PRV set at 25psi. If it doesn’t have a 25psi prv it can only be transported by a hazmat LIC holder.
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The DOT is concerned about the quantity of hazardous material you are transporting and allows you to transport 1,000 lbs or less without HazMat certification (includes the weight of the storage vessel).