Interpretation ID: 1985-01.11

TYPE: INTERPRETATION-NHTSA

DATE: 01/11/85

FROM: AUTHOR UNAVAILABLE; Frank Berndt; NHTSA

TO: Herbert R. Apuzzo -- Laboratory Supervisor, American Safety Equipment Corporation, Corporate Quality Assurance & Reliability

TITLE: FMVSS INTERPRETATION

TEXT:

Mr. Herbert R. Apuzzo Laboratory Supervisor American Safety Equipment Corporation Corporate Quality Assurance & Reliability 11441 Bradley Avenue Pacomia, CA 91331

This responds to your letter of September 25, 1984, to Mr. William Smith which was forwarded to this office for reply. You asked several questions concerning the requirements of section 5.2(b) of Standard No. 209, Seat Belt Assemblies, which are answered below.

Your first question concerns the conditioning requirements of Procedure D of ASTM D756-78, which is incorporated by reference in Standard No. 209. You pointed out that the agency' s compliance test procedure (document TP-209-01) calls for conditioning for 24 hours, while ASTM D756-78 calls for conditioning for not less than 40 hours. The conditioning requirement incorporated by reference in Standard No. 209 is the correct version and is the method which will be used by the agency. The version of the agency's compliance test procedure you cite was prepared before the June 30, 1983, amendments to Standard No. 208 which adopted ASTM D756-7B. The compliance test procedure will be revised to specify not less than 40 hours of conditioning.

Your second question concerned the requirement of Procedure D that part of the testing be done in a sealed container placed over water in a 176oF recirculating oven. The test calls for maintaining "a humid atmosphere" in the sealed container. You asked what percentage of humidity should be maintained.

You are correct that Procedure D does not specify the specific percentage of humidity. However, section 6.2, Test conditions, of ASTM D756-78 specifies that the tests should be conducted in the Standard Laboratory Atmosphere of 23 +- 2oC and 50 +- 5% relative humidity "unless otherwise specified in the test methods or in this practice." Since Procedure D does not specify a humidity level, the agency will use the humidity of 50 +- % relative humidity specified in section 6.2.

You also asked whether a recirculating chamber can be used to conduct the test. The test equipment specified in the standard is the equipment the agency will use in its compliance tests. Manufacturers are free to use other test equipment as long as they can make a good faith certification that their product complies with the requirements met in the standard.

Your final question concerns another difference between ASTM D756-78 and the compliance test procedure. As explained above, the version of the compliance test procedure you cite was prepared before the June 1983 amendments to the standard and will be updated to cite the requirements adopted in those amendments. You asked for a description of "dessicator" and "uncharged dessicator" referred to in ASTM D756-7B. A dessicator is a closed container that has a drying agent to absorb moisture. An "uncharged dessicator" is a dessicator that does not have a test specimen in it.

In addition, you asked whether you could use an environmental chamber rather than a dessicator. As discussed previously, the test procedures and equipment specified in the standard are the procedures and equipment which the agency will use in its compliance tests. Manufacturers are free to use other test equipment and procedures as long as they can make a good faith certification that their product complies with the requirements set in the standard.

If you have any other questions, please let me know.

Sincerely,

Frank Berndt Chief Counsel September 25, 1984

Mr. William E. Smith Office of Vehicle Safety National Highway Traffic Safety Administration 400 Seventh Street, Southwest Washington, D.C. 20509

Mr. Smith,

American Safety Equipment Corporation, a major manufacturer of Seat Belt Restraint Systems, requires an interpretation of a long-standing but updated ASTM Standard identified in FMVSS-209, paragraph SS.2(b) "Hardware Temperature Resistance".

The Federal registry, under docket 48 FR 30138 (June 30, 1983) amended said paragraph to include updated ASTM D756-78, procedure D, which did not incorporate present standard industry practices.

In this regard, would you please review the following and inform American Safety Equipment of your interpretation.

1. Paragraph S5.2(b) calls for "Conditions prescribed in procedure D of ASTM D756-78" which in turn calls for conditioning at 73.4 +- 3.6 F and 50 +- 5% RH. for not less than 40h, per ASTM Methods D618, while TP-209-01 (page C-1) calls for conditioning for 24 hours. It is our understanding that 24 hours conditioning (as called out in TP-209-01) is "Standard" in the automotive industry, as opposed to the 40 hour conditioning period identified in ASTM D756.

Question: Will both methods satisfy the requirements of FMVSS-209?

2. ASTM D756-78, Procedure D calls for testing "OVER WATER" (at 176o F, in recirculating oven) in sealed container with small capillary "To maintain a humid atmosphere", but does not mention any specific percentage of relative humidity. In general practice, environmental chambers capable of relative humidity from near-zero to 100% are being used to maintain high humidity.

Question: What percentage of humidity can be expected with the "OVER WATER" method, and will recirculating chambers satisfy this requirement?

3. ASTM D756-78, calls for bringing specimens to room temperature in an "Uncharged dessicator which will require 10-30 minutes", then within 2h of exposure over water, expose the specimen for 24h in the oven at 176o F.

TP-209-01 states: "Within two humid of the humid exposure, place the specimens in a DRY HEAT OVEN which has been pre-conditioned to a temperature of 176 = 1.8o F for 24 hours, but does not mention the use of an uncharged dessicator for 10-30 minutes.

Question: Would you please provide us with a description of "Dessicator" and "Uncharged Dessicator" and a determination as to the acceptability of an environmental chamber set at 73.4 +-3.6oF and 50 +- 5% RH to bring specimens to room temperature and then to 176 +- 1.8oF dry heat.

We would appreciate your response (written) at your earliest possible convenience so that American Safety Equipment can maintain the most accurate test conditions possible.

Thank you,

Herbert R. Apuzzo Laboratory Supervisor American Safety Equipment Corporation Corporate Quality Assurance & Reliability 11441 Bradley Avenue Pacoima, CA 91331

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cc: F. Neumann T. Israelson