Interpretation ID: 3231yy
Legris Incorporated
244 Paul Rd.
Rochester, N.Y. 14624
Dear Mr. Byrd:
This responds to your September 23, 1991 letter asking about the air pressure requirement specified in S7.3.8 of Standard 106, Brake Hoses. Your letter has been referred to my office for reply.
Paragraph S7.3.8 states that an air brake hose assembly shall contain air pressure of 200 psi for 5 minutes without loss of more than 5 psi. You ask whether Standard 106 specifies the length of the hose for an assembly tested to S7.3.8. The answer is no; the standard does not have a generic specification for hose length. Instead, each brake hose assembly is required to meet this requirement as manufactured and sold.
For purposes of compliance testing, NHTSA obtains a brake hose assembly specimen by purchasing it on the market or directly from the manufacturer. The length of the hose might vary from assembly to assembly, depending on the particular configuration of an assembly. The assembly is tested as sold to obtain performance results that indicate the assembly's real world performance.
While S7.3.8 is a performance requirement for assemblies, we understand that your company (an end fitting manufacturer) seeks to ensure that an assembly made with your fitting will not fail to meet S7.3.8 due to the fitting. Since an assembly is tested to S7.3.8 in the configuration in which it is sold, you could test to the requirement using the length of hose that will be used with your fitting. Legris might be able to avoid duplicative tests by conducting "worst case" testing, such as tests using a fitting with a hose of a length most likely to exhibit an excessive loss of air pressure.
Please contact us if you have further questions.
Sincerely,
Paul Jackson Rice Chief Counsel /ref:106 d:ll/l5/9l