Marking and Testing of a Combination Package
Pipeline and Hazardous Materials Safety Administration · Mar 24, 2004 · Reference No. 02-0232
Interprets: 49 CFR § 178.2, 49 CFR § 178.503, 49 CFR § 178.603
Reggie’s quick take
Someone asked whether a glass-bottle combination packaging can carry the higher gross weight tested for a metal-can version, and how to set drop height when liquid specific gravity is unknown. PHMSA says no to the higher weight under § 178.503(a)(3). Both marks may appear, but unless the inapplicable one is covered or obliterated, it may confuse and violate the rules. The proposed drop-height formula is not in accordance with § 178.603(e)(2)(ii). If it gives a height greater than the minimum, that greater height may be used for testing.
Written by AI (Claude) on Oct 22, 2026. Robots make mistakes and leave things out, so the letter below is what counts. Not legal advice.
This is in response to your letter requesting clarification of the requirements of the Hazardous Materials Regulations (HMR: 49 CFR Parts 171-180) regarding the marking and testing of a combination packaging. Your questions are paraphrased and answered below.
Q1. One combination packaging consists of an outer 4G fiberboard box and an inner metal can with a gross mass of 7.3 kg. Another combination packaging consists of an identical outer 4G fiberboard box and an inner glass bottle with a gross mass of 5.3 kg. May the packagings be marked with the highest gross mass tested, or must the packaging be dual marked with both the higher and the lower gross weights?
A1. For a packaging containing the inner glass packaging, in accordance with § 178.503(a)(3), it is not appropriate to mark the packaging to a higher gross weight than for which it was tested. The packagings may be marked with both specification markings. However, unless the non-applicable marking is covered or obliterated, the dual marks may cause confusion and could result in a violation of the regulations. The conditions for use would have to be clearly set forth in the notification to users required by § 178.2(c).
Q2. When testing a combination packaging and the specific gravity of the liquid is unknown, may we use the formula "PG drop height X desired gross mass ÷ actual package gross mass adjusted drop height," which is based on the desired gross mass of the packaging, to determine the adjusted drop height under § 178.603(e)(2)(ii)?
A2. The formula you presented in your letter is not in accordance with the formula provided in § 178.603(e)(2)(ii) of the HMR. Based upon the formula and the information provided in your letter the minimum-acceptable drop height can be calculated without knowing the maximum specific gravity of the product that will be packaged. The correct formula derived from the revised drop height calculations presented in § 178.603(e)(2)(ii) is as follows:
H = (M-T) X D/W
Where
H = Drop height
M = Certified gross mass
T = Tare weight of packaging
D = Variable for correcting Packing Group (1.5, 1.0 or .67 meters)
W = Weight of water in kg or Volume of water in liters
Using the example from your letter (after converting to kg) the correct calculation is:
H = Drop height
M = 6.4 kg
T = 0.7 kg
D = 1.0 for Packing Group II
W = 3.8 liters or kg
H = (6.4-0.7) X 1.0/3.8 = 1.5 meters
Your formula provides for a drop height of:
H = 1.2 X 6.4/4.5 = 1.7 meters
If in all cases your formula provides for a height that is greater than the minimum required by the HMR, it is acceptable to use the greater height for package testing as the HMR provide the minimum requirements for testing a package.
I hope this information is helpful. If you have additional questions, please contact this office.
A letter of interpretation applies the regulations to the facts the requester described. It isn’t a regulation and isn’t legal advice. The agency’s copy.