The Journal ofHazMat Transportations™ Exclusive Comments on Current U.S. DOT Letters of Interpretation of the Hazardous Materials Regulations

摘要

While the incoming letter is specific to packaging requirements for nitric acid in § 173.158, the response is generally applicable. The questioner asks PHMSA to clarify what is actually meant when the regulation limits a packaging's capacity to, in this case, not over 2.5 L. While the question is specific to one particular section of the regulation, the questioner, may as well have asked, "When the regulations specify a packaging capacity limit for a liquid packaging, does that limit refer to the amount of liquid that may be put into the package (the filling capacity or nominal capacity) or does it refer to the capacity when the package is brim full (or overflow capacity)?" To meet the general packaging requirements (see §§ 173.24(h)(l) and 173.24a(d)), packagings may not be filled to the brim. There must be a certain amount of ullage to allow for expansion of the liquid in transport. Without any air space, expanding liquid could force liquid out through the closure, cause plastic packages to swell, or possibly cause the package to fail. Usually leaving 2% ullage will suffice, although in some cases, the regulations specifically prescribe higher ullage volumes for added safety.