Shipping or traveling by air with Rare Earth Magnets

Recently, when I purchased some magnets, I noticed the box that they came in was labeled: "Not packed for shipment by air." What does this mean?

The box was small, only holding a few rare earth magnets in a zip-lock bag and the entire box was filled with crushed paper. I began to think, "what more was needed to ship this package by air"? Is there a concern with the pressure in the baggage compartment of the plane? Could the few magnets in the box effect flight instruments? Neither seemed possible or a significant issue. 

So, I looked into it further. First, I found that magnetized material is NOT regulated as a hazardous material when transported via ground/surface transportation. However, the U.S. Department of Transportation has determined that rare earth magnets pose a safety risk when shipped by air unless they are specially packaged. Many suppliers do not provide such specialized packaging, and therefore do not transport via air. Perhaps they do not want to take the time to concern themselves with the added time to determine this. We know of one trusted supplier who does, to see how they ship their magnets via air, see the link below for K & J Magnetics.

It is important to realize that when groups of magnets are in close proximity to one another, their field forces unify and thus increase. Therefore if a large or moderate quantity of magnets are shipped together, shielding of some sort could be necessary.

Is it safe to take magnets on airplanes? Yes and no. Magnets can affect the navigational equipment on an aircraft. However, most single small magnets are not capable of significantly affecting these instruments from a moderate distance. But to determine exactly how strong a magnet(s) would have to be to affect the instruments, and how close they would need to be to do so, the US Department of Transportation and the International Air Transport Association have set precise guidelines for the transport of magnets by air. If the magnets you are transporting exceed certain thresholds, they will be considered Class 9 Hazardous Materials and should only be placed on an aircraft by trained and certified personnel. 

So, what are the rules?

According to K & J Magnetics,
"There are two important measurements of a package containing magnets. Rule #1: If the field strength is 2 milligauss (0.002 gauss) or more at a distance of 7 feet from the package, the IATA (International Air Transport Association) says the package needs to be labeled as Magnetic (see below). This is especially applicable for international shipments.

This label would be placed on a package containing magnets being shipped via air.

Magnets are often shipped in a steel-lined box to remain below this limit.

If there is any chance that the arrangement of magnets could change, or any package shielding could be damaged so that a measurement exceeds this value, it falls under the Dangerous Goods category and should be labeled as Magnetic.

Rule #2: For any package shipped by air, whether it is labeled magnetic or not, the field strength must be 5.25 milligauss or less at a distance of 15 feet from the surface of the package (FAA Title 49, Part 173.21 Forbidden materials and packages). If the package measures above this value, don't ship it by air.

Why are these rules so important? The magnetic compass. Despite all the fancy GPS navigation systems, the basic compass is still an important part of aircraft navigation. If a cargo of magnets alters the compass readings, accurate navigation might be compromised.

Remember, your magnets are competing with the magnetic field of the Earth, whose strength is only about 0.5 gauss on average."

So the short answer is that a magnetized material is considered a hazardous material and is regulated as a hazardous class 9 material when it is offered for transportation by air and when it has a magnetic field strength that is capable of causing the deviation of aircraft instruments. 

This image from K&J Magnetics shows a packing
method to keep magnets as far from the box walls as possible.

So how do you put this into practice? Well one way is with the use of a compass. That's right that ancient tool that was invented when the mysteries of magnets and Lodestone were first put to use. With your compass you can also measure the field distance of the magnets inside a box. (The first link below also includes a great youtube video showing this!) Remember, the farther away from a magnet you are the more the field force drops.

Read more of K & J Magnetic's article at: https://www.kjmagnetics.com/blog.asp?p=shipping
some other sites to visit:
http://www.rare-earth-magnets.com/t-safetyinformation.aspx

http://www.mceproducts.com/knowledge-base/article/article-dtl.asp?id=10

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Gwen Spicer is a textile conservator in private practice.  Spicer Art Conservation specializes in textile conservation, object conservation, and the conservation of works on paper.  Gwen's innovative treatment and mounting of flags and textiles is unrivaled.   To contact her, please visit her website.

Learn more about magnets and their many uses in the new publications Magnetic Mounting Systems for Museums and Cultural Institutions. Available for purchase at www.spicerart.com/magnetbook.