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Electronic Code of Federal Regulations
Title 49: Transportation
Appendix B to Part 172—Trefoil Symbol
1. Except as provided in paragraph 2 of this appendix, the trefoil symbol required for RADIOACTIVE labels and placards and required to be marked on certain packages of Class 7 materials must conform to the design and size requirements of this appendix.
2. RADIOACTIVE labels and placards that were printed prior to April 1, 1996, in conformance with the requirements of this subchapter in effect on March 30, 1996, may continue to be used.View or download PDF
1=Radius of Circle—
4 mm (0.16 inch) for markings and labels
12.5 mm (0.5 inch) for placards
3=5 radii for markings and labels
41⁄2 radii for placards.
[60 FR 50306, Sept. 28, 1995, as amended by 172-143, 61 FR 20750, May 8, 1996]