Interpretation ID: 1984-1.18

TYPE: INTERPRETATION-NHTSA

DATE: 03/01/84 EST

FROM: AUTHOR UNAVAILABLE; Frank Berndt; NHTSA

TO: Asahi Glass Co. Ltd. -- Seiroku Miyauchi

TITLE: FMVSS INTERPRETATION

TEXT:

Mr. Seiroku Miyauchi Plastic Products Dev. & Marketing Div. Asahi Glass Co., Ltd. 1-2, Marunouchi, 2-Chome Chiyoda-ku, Tokyo, 100 Japan

This responds to your letter to Mr. Francis Armstrong asking several questions about Standard No. 205, Glazing Materials. The answers to your questions are discussed below.

Your first question concerned the requirements of Weathering Test No. 16 of American National Standard Institute Z-26. The version of ANSI Z-26 currently incorporated by reference in Standard No. 205 is ANSI Z-26.1-1977, as supplemented by Z-26.1a, July 3, 1980, rather than ANSI Z-26.1-1977 as cited in your letter. Your question has to do with the language of section 5.16.3 of ANSI Z-26, which states that after the weathering test, "the decrease in regular (parallel) luminous transmittance of the irradiated specimen shall not exceed 5 percent." You ask whether the permissible decrease is an absolute 5 percentage points (defined as A-B, where A is the luminous transmittance before the test and B is the luminous transmittance after the test) or is a relative decrease of 5 percent (defined as (A-B)/A). The permissible decrease is a relative decrease of 5 percent (defined as (A-B)/A), or stated another way, the irradiated specimen must have 95 percent of its original transmittance after the test.

You also asked if Weathering Test No. 16 applies to AS-7 glazing materials. As required by Table 1 of ANSI Z-26, the weathering test does apply to AS-7 glazing materials.

Finally, you asked which DOT number, yours or the resin maker's, should be applied to a motorcycle windshield you make with an injection machine from polycarbonate resin pellets. Your DOT number must be used, since you fabricate the actual item of glazing material that will be placed in a vehicle.

Sincerely, Frank Berndt Chief Counsel

Dec. 26, 1983

Mr. Francis Armstrong Director Office of Vehicle Safety Compliance Enforcement National Highway Traffic Safety Administration 400 Seventh Street Sw. Washington D.C. 20590 U. S. A.

Dear Mr. F. Armstrong :

This is a letter in response to your letter of December 8, 1983. We appreciate your kind cooperation very much. This time, we would like to inquire you the following questions.

(1) Concerning the weathering test (test No.16 of ANS Z26.1-1977) It describes that the decrease in luminous transmittance of the irradiated specimens shall not exceed 5%. Would you tell me the meaning cf the above mentioned decrease ? It can be defined as either way ... (A-B)/A or (A-B) A : the luminous transmittance before test B : the luminous transmittance after test We think (A-B) is correct. Because if (A-B)/A is correct, the allowable decrease (A-B) is relatively smaller in proportion to the smaller A value. And in addition, is the above criteria applied to AS-7 grade, which is defined at the level not requisite for driving visibility?

(2) Concerning the marking of safety glazing materials. We purchase the polycarbonate resin pellets from resin makers, and mold windscreens for motorcycles with injection machine. In this connection, which DOT number should we mark the resin maker's number or our number ?

Your prompt answer will be much appreciated.

Yours Sincerely,

( Seiroku Miyauchi ) Technical Manager Plastic Products Dev. & Marketing Div. Asahi Glass Co., Ltd.

SM / yy