Cracking the Code — Explaining UN Ratings
You probably know that you need DOT packaging or some kind of special container to ship dangerous goods. You may even know that these special containers require a UN rating. But do you know what UN rating each container needs to have? This is essential to know because it is the responsibility of the shipper to choose the correct packaging, and you can’t pick the right packaging if you don’t understand what UN ratings mean. So we’re here to help you decipher them.
“UN” refers to “United Nations,” as in United Nations performance standards, and it’s an internationally recognized system. Let’s take a closer look at UN ratings for solids and liquids.
Consider a rating of UN 1A2/X430/S.
This is a rating for a container that holds solids because of the S on the end. However, what do all those other letters and numbers mean? Let’s start from the beginning.
The 1 refers to the fact that this is a drum. If it were another type of container, the following could be noted instead:
- 1 - drum
- 2 - wooden barrel
- 3 - jerrican
- 4 - box
- 5 - bag
- 6 - composite receptacle
- 5 - pressure receptacle
The A represents what material the container is made of. In this example, it is a steel container.
- A - steel
- B - aluminum
- C - natural wood
- D - plywood
- F - reconstituted wood
- G - fiberboard
- H - plastic
- L - textile
- M - paper, multiwall
- N - metal other than steel or aluminum
- P - glass, porcelain or stoneware
The 2 refers to the fact that it is an open-head drum. A closed-head drum, or drum with no removable top, would be designated with a 1. (There could also be a T designation, which would mean that leakproofness is tested with water, rather than some other media.)
The next designation is the
- X packaging covers all three packing groups: I, II, or III
- Y packaging covers packing groups II and III only
- Z packaging covers packing group III only
The final number in our example – 430 – refers to the maximum gross mass that the container has been tested to handle. This refers to the amount of weight that the drum plus its contents has been tested to hold. Although it might actually be able to hold a higher weight, the UN rating denotes the weight it’s been tested to hold. If you ship over what the drum is tested for, you risk being cited.
The difference between liquid and solid ratings
The liquids ratings aren’t much different. For example, using the designations above, a rating of UN 1H1/Y1.9/100 means that this is a drum (1), that it’s plastic (H) and closed-head (1). It lists a Y rating, which means it can hold packing groups II and III.
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In this case, the 1.9 refers to the maximum specific gravity of the liquid that this container has been tested to hold. The 100 refers to the maximum hydrostatic pressure that the container can hold.
Another thing to remember about UN ratings is that you can always pick one higher than what you need, but not lower. For example, a liquid with a specific gravity of 1.8 can go to a container that has a 1.9 rating, but not 1.7. If you have a material that is in packing group II, you can choose an X- or Y-rated container, but not a Z.
Shipping hazardous materials in the proper container helps ensure safety, preserve the environment and prevent costly fines associated with non-compliance.