Interpretation ID: nht81-3.45
DATE: 11/30/81
FROM: AUTHOR UNAVAILABLE; Frank Berndt; NHTSA
TO: United States Testing Company Inc.
TITLE: FMVSS INTERPRETATION
TEXT: This responds to your July 24, 1981, letter directed to our Office of Enforcement in which you ask whether it would be permissible to test for compliance with Standard No. 302, Flammability of Interior Materials, in a manner different than that prescribed in the standard. The standard states that a 14-inch long section of material shall be burned in a test oven until the flame reaches within 1 1/2 inches from the end of the material. You state that for some fabrics this requires a test that can extend to 10 minutes. In a test of this length, the heat buildup in the test oven can cause the glass front of the oven to break. You suggest that the test be discontinued after five minutes, and the burn rate calculated.
The test requirements of the standard are provided to show how the agency will test for compliance. However, it is not compulsory that a manufacturer adhere to every facet of the test procedures if it can satisfy itself that its product will comply with the standard by testing in another manner.
As you know, the standard requires only that the burn rate of a material not exceed four inches per minute. A 14-inch long section of material that has not burned completely to its end in five minutes obviously would not exceed the 4-inch per minute burn rate. Accordingly, we do not see any reason that you could not terminate the test five minutes after the starting point specified in paragraph S5.3(e) of the standard.
SINCERELY,
United States Testing Company, Inc.
July 24, 1981
Department of Transportation National Highway Traffic Safety Administration Office of Standards Enforcement
Enforcement Director:
Our laboratory has been conducting tests for conformance to FMVSS 302 for many years. In the last couple of years we have noticed that certain materials although very slow burning create so much heat within the chamber that the heat resistant glass on the front of the cabinet shattered.
If one stays in strict compliance with the test procedure, the material being tested must be allowed to burn for a distance of 10 inches in the timing zone. In order to prevent excessive heat build up with possible harmful side effects, it might be suggested to abort the testing after 5 minutes of timing and calculate the burn rate on the length burned in 5 minutes.
Since this is not incorporated in any part of the test procedure, may we ask for your opinion in this regard.
Although we are highly concerned for the safety of our technical help and take all necessary precautions, we feel that the suggested approach should be either spelled out in future revisions or that a statement be issued by the Department of Transportation with regard to this problem.
G. R. Dufresne Assistant Vice President