UN Ratings: Understanding UN Markings (Part 2 of 3)

When shipping hazardous material, your packaging or container must have the proper UN rating. As explained in our previous article, UN Ratings: Solving The Puzzle, UN ratings were adopted by the US Department of Transportation (DOT) to ensure the efficient and safe transportation of hazardous materials internationally. Now that you know why UN ratings are necessary, let's explain how to understand and correctly read the labeling.

As seen below UN ratings can look a little intimidating but once broken up and explained they become quite easy to decipher between.

UN Markings

UN Symbol

The UN symbol is a lowercase "u" over a lowercase "n" in a circle or an uppercase "UN."

UN Rating Symbol

Packaging Identification Code

The first set of numbers following the UN symbol is known as the Packaging Identification Code. This section consists of the Package Type, Material, and Category.

UN Rating Packaging Identification Code

Package Type (Type of Container)

1-Drums/Pails 3-Jerricans 5-Bags 7-Pressure Receptacle
2-Barrels 4-Boxes 6-Composite Packaging


A-Steel F-Reconstructed Wood M-Paper,Multiwall
B-Aluminum G-Fiberboard N-Metal other than Steel/Aluminum
C-Natural Wood H-Plastic P-Glass,Porcelain,Stoneware
D-Plywood L-Textile


1-Closed Head (one molded piece) 2-Open Head (removable lid)

Packing Group Level Equivalent

Packing Group Level Equivalent section labels what hazard level your product falls under and how dangerous it is.

UN Rating Packaging Group

Packing Group

X-High Hazard Level Y-Medium Hazard Level Z-Low Hazard Level
Packing Group l,ll,lll Packing Group ll,lll Packing Group lll

*You can determine which packing group your material falls into by using the HAZMAT Table.

Specific Gravity - is the ratio of the density compared to the density of water at a specific temperature and pressure.

Hydrostatic Pressure Test

Hydrostatic pressure test is a vapor pressure measured in kilopascals (kPa) rounded down to 1 decimal The results to one of the 5 tests required in UN ratings

UN Rating Hydrostatic Pressure Test

It is important to note that the above 2 numbers are for labeling liquid material only. When labeling solids you would use the Maximum Gross Mass (kg) instead of Specific Gravity and then a Letter “S” instead of a number for the hydrostatic pressure test. (Refer to figure 1)

Year of Manufacture

The Year of Manufacture refers to the year the packaging was manufactured.

UN Rating Year of Manufacture

Country of Origin (Location of Manufacture)

The Country of Origin refers to the location where the package was manufactured.

UN Rating Location of Manufacture

Manufacture Code

The Manufacture Code is the code for UN certified agency or manufacturer.

UN Rating Manufacture Code

UN ratings tell you the description of the container as well as requirements to certify the product that you are packaging. It is very important that the containers are labeled with the correct UN rating.

Now that you know each section of a UN rating you can tell everything about that packaging just by looking at it. If you have any more questions or concerns on the matter we are always available at The Cary Company.

Continuing Reading (Part 3 of 3) - UN Ratings: Switching Liquids & Solids