Regulationhistorical
49 CFR 179.220-4
Insulation.
Snapshot 2019-10-01 Government source
eCFR editorial compilationAuthoritative but unofficial
View source The annular space between the inner container and the outer shell must contain an approved insulation material.
[Amdt. 179-9, 36 FR 21340, Nov. 6, 1971]