Interpretation ID: nht90-1.50

TYPE: Interpretation-NHTSA

DATE: February 20, 1990

FROM: David G. Dick -- Technician, Toy Laboratory, ACTS Testing Labs, Inc.

TO: NHTSA

TITLE: None

ATTACHMT: Attached to letter dated 9-10-90 from P.J. Rice to D.G. Dick (A36; Std. 213)

TEXT:

This letter is to request an interpretation of the National Highway Traffic Safety Administration, Department of Transportation, Code of Federal Regulations, Title 49, Transportation, Part 571.213, S5.2.3 Head Impact Protection requirements.

Section 5.2.3.2(a) of the Standard requires a 25% compression-deflection resistance of not less than 0.5 and not more than 10 pounds per square inch (psi) when tested in accordance with Section 6.3 for the energy absorbing material.

The requirements of not less than 0.5 and no greater than 10 psi are listed in the standard to one significant figure, however, when specimens are tested in accordance with the specified methodology, the results are calculated to more than one significan t figure. Is it acceptable to round off the result to one significant figure as stated in the standard as seen in the below example?

i.e.: 0.47 would be rounded up to O.5 and reported as a Pass.

Additionally, how was the lower limit of 0.5 psi decided upon?

Is there any situation in which an energy absorbing material with a 25% compressiondeflection resistance of less than 0.5 psi acceptable?

Your quick response to these questions would be greatly appreciated.