Cleared for Travel? Using a Gaussmeter to Check Magnetic Materials Before ShipmentMarch 1, 2005 By: Jim McHan Sensors
Sypris Test & Measurement, Inc., manufactures high-precision, high-resolution gaussmeters. Magnet and magnetized manufacturers and shippers can use these devices to test packages for compliance with FAA and International Civil Automation Organization (ICAO) requirements for shipping these materials by air. First we'll discuss the regulations involved, and then we'll explain the setup and equipment required to achieve compliance.
The FAA adheres to the U.S. Department of Transportation's (DoT) Office of Hazardous Materials Safety's "Code of Federal Regulations." As stated in CFR49, section 173.21, it is forbidden to offer for transportation or to transport any package with a magnetic field of >0.00525 gauss (G) measured at 15 ft. from any point on the surface of the package. The FAA imposes strict penalties for violations. Even stricter standards were adopted in 2004, requiring packages to carry a special sticker certifying the package as air eligible.
Most passenger and cargo airlines, however, adhere to the more stringent International Air Traffic Association (IATA) regulations. The IATA Dangerous Goods Regulations is a "field manual" version of the ICAO's technical instructions. As of 2003, the IATA's classification and definition of "magnetized material" was "any material which, when packed for air transport, has a magnetic field strength of 0.002 G or more at a distance of 7 ft. from any point on the surface of the package."
The packages must be checked for total magnetic field emission: If the field exceeds 0.002 G at 7 ft. from any point on the surface of the package, then packaging instruction 902 in the IATA dangerous goods regulation must be followed. If the total field emission exceeds 0.00525 G at 15 ft. from any point on the surface of the package, the package cannot be accepted for air shipment. If the 0.00525 G requirement is met, you can ship the package by air on an international flight provided you fill in the dangerous goods declaration form and label the package appropriately. The package must have the label for handling of Class 9 magnetized materials.
Important: The above is for information purposes only and does not fully state the regulations. Be aware that you cannot rely on the general summary above to make decisions; rather, you should know that these regulations exist and that you must refer to them.
Measuring Magnetic Fields
Figure 1. Sypris's 7030 gaussmeter with a 3-axis probe provides resolution down to 0.1 mG. The system is also capable of displaying the vector sum value, thus eliminating the uncertainty of single-axis measurements.
The probe contains three orthogonal Hall effect devices in its tip (see Figure 2). The gaussmeter automatically corrects each Hall effect device for nonlinearity and displays the individual X, Y, and Z components of the magnetic field as well as their vector sum.
Figure 2. This diagram shows the ZOA73-3208-05 3-axis probe Hall effect sensor locations. The close proximity of the Hall effect devices ensures accurate and reliable vector sum magnetic field measurements.
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