4L DOT Standards- Size by Default

A client called today with an issue related to a 4L-DOT cryogenic liquid vessel. At question was the size of the vessel and the concern was that the vessel was over 119 gallons.

It will be interesting to see how their issue is resolved since according to the 49CFR Sec. 178.57 Specification 4L welded insulated cylinders. "(a) Type, size, service pressure, and design service temperature. A DOT 4L cylinder is a fusion welded insulated cylinder with a water capacity (nominal) not over 1,000 pounds water capacity and a service pressure of at least 40 but not greater than 500 psig......"

Since water weighs 8.3453 pounds per gallon this means that the absolute maximum capacity of a 4L vessel would be 119.83 gallons. Most vessels have some head space allowance so nominal capacities for the largest 4L cryogenic liquid cylinders tend to be under 119 gallons. But- depending on the specific vessel, the water capacity could technically be 119 point something, but under 120 gallons.

So- like I said, it will be interesting to see what comes of their question. As always- any comments on this are welcomed.