UN Ratings: Solving The Puzzle (Part 1 of 3)

When it comes to UN ratings there are many questions and concerns on what is required, why they are needed, what they mean and if it concerns you. We understand where the confusion lies and The Cary Company is here to help solve this confusion. We are releasing a series of articles starting to explain and educate our customers on why UN ratings are needed, how to specifically read them, and details regarding the differences between packaging liquids and solids and when the packaging can be mixed.


Guide to UN RatingsIn the early 1990’s, the US Department of Transportation (DOT) adopted the Performance Oriented Packaging (POP) to regulate and unify international shipments of hazardous material. Hazardous material can be very dangerous if not handled properly. Many countries therefore developed their own specifications on properly shipping these materials. Problems started to arise when conflicting regulations between countries started to contravene the shipment of these hazardous goods. What would be a suitable shipment to one country would not pass another’s test. It was then that the United Nations Committee of Experts on the Transport of Dangerous Goods created a solution to streamline the regulations by developing international standards known as UN Ratings.


UN Markings on BoxA UN Rating is located on the outside of a container or packaging and lists the properties and limitations of the container in a series of numbers and letters. The packaging should be marked permanently (embossed) on the bottom and on either the side or the top. The bottom marks are known as the birth certificate of the container's original performance capability.

For Example a UN rating might look like this:


The rating informs the user that the package is suitable and safe to transport. In order for a package to become UN rated it has to pass a series of tests to prove that the design is acceptable for the international transportation of the hazardous material. It is important to note that a UN rating does not indicate chemical compatibility with a container.

For example, if you plan on putting hazardous material inside of a UN rated container you have to make sure you have the correct material for the chemical. UN ratings only reflect the containers ability to pass the following 5 Performance Tests.

  1. Hydrostatic Test
    • Containers are filled with compressed air and submerged for at least 5 minutes
  2. Leak Proofness
    • Containers are filled up to overflow and internal pressure applied
  3. Stack compression
    • Containers are stacked for 28 days at 104 degrees Fahrenheit or higher
  4. Vibration test
    • Containers are shaken until a 1/16 inch plate can slide under the container
  5. Drop Test
    • Containers are dropped with the center of gravity over the impact point

The above 5 Performance Tests are set in place in order to simulate key aspects of a possible transportation and storage route.


It is the responsibility of the shipper to comply with the regulations and determine the proper packaging. The shipper needs to ensure that the packaging is authorized, properly manufactured, assembled, and marked.

It is important to know that any non-compliance results in a costly fine.


The following materials are all considered HAZMAT and require a UN rating in order to be shipped.

Flammable Gas Warning for UN Ratings

  • Explosives
  • Non-flammable gas
  • Flammable gas
  • Flammable liquid (*)
  • Infectious substance
  • Corrosives (*)
  • Flammable solid (*)
  • Oxidizers
  • Organic peroxide
  • Toxic materials
  • Radioactive material

(*) - most common hazard classes for UN certified classes

As you can see the United Nations require UN ratings in order to make the shipping of hazardous materials safer and easier internationally. UN ratings help preserve the environment, demand safety for the people who are transporting the goods and allow efficiency across country lines.

If you have any questions The Cary Company would be happy to help you and provide further explanation.

Continue Reading (Part 2 of 3) - UN Ratings: Understanding UN Markings