Interpretation ID: nht81-1.36

DATE: 03/11/81

FROM: AUTHOR UNAVAILABLE; F. Berndt; NHTSA

TO: Cosco

TITLE: FMVSS INTERPRETATION

TEXT:

MAR 11 1981

Mr. Don Gerkin Product Engineer COSCO 2525 State Street Columbus IN 47201

Dear Mr. Gerkin:

This responds to your letter of January 8, 1981, concerning Standard No. 213, Child Restraint Systems. You asked whether urethane foam can be used to meet the requirement of S5.2.3.2 of the standard. The answer is yes.

S5.2.3.2 provides, in part, that:

Each system surface . . . which is contactable by the dummy head when the system is tested in accordance with S6.1 shall be covered with slow-recovery, energy-absorbing material with the following characteristics . . . .(Emphasis added.)

The purpose of S5.2.3.2 is to require the use of material that will protect a child's head in an impact. To protect the child's head, the material must be capable of dissipating the force of the impact (i.e., energy-absorbing).

To prevent the use of material that will rebound immediately after impact or will not recover after one impact, the standard requires the use of slow-recovery material. That requirement acts as an additional safeguard to ensure that the material absorbs the energy of the impact to prevent injury and does not act as an energy storer or spring that, upon rebound, releases the full energy of the initial impact. In addition, the requirement prevents the use of material that cannot recover after being impacted once (e.g., styrofoam). As you pointed out, certain types of urethane foam can absorb energy and do not immediately recover or rebound after impact and are thus permissible.

Sincerely, Frank Berndt Chief Counsel

Mr. Frank Berndt, Chief Counsel U.S. Dept. of Transportation National Highway Traffic Safety Administration 400 Seventh Street, S.W. Washington, DC 20590

January 8, 1981

Dear Mr. Berndt:

When the Standard No. 213 Child Restraint Systems was published, one of my many tasks was to find a slow recovery, energy absorbing material to cover surfaces for compliance to head impact protection.

After an extensive search, we settled on using Ensolite Foam in our Child Restraints, a very expensive product compared to Urethane Foam. I have tried, without success, to obtain a definition of slow recovery, energy absorbing material from manufacturers as well as NHTSA.

It appears to me now that inexpensive Urethane Foam that meets the thickness and compression requirements would comply to the 213 Standard. Urethane Foam does absorb energy and recover - at some rate.

Assuming our Child Restraints pass all other criteria of the Standard, and we did use Urethane Foam, would we still be in compliance to the Standard?

As there would be a large savings to our company if we could make a turn-around from Ensolite to Urethane Foam, your prompt attention to this matter will be greatly appreciated.

Sincerely,

Don Gerken Product Engineer

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