Interpretation Response #07-0072 ([Sherwood, Harsco Corporation] [Ms. Mia R. Daniels ])
Below is the interpretation response detail and a list of regulations sections applicable to this response.
Interpretation Response Details
Response Publish Date:
Company Name: Sherwood, Harsco Corporation
Individual Name: Ms. Mia R. Daniels
Location State: PA Country: US
View the Interpretation Document
Response text:
Jun 28, 2007
Ms. Mia R. Daniels Reference No. 07-0072
Director of Engineering
Sherwood, Harsco Corporation
2200 North Main Street
Washington, PA 15301
Dear Ms. Daniels:
This is in response to your March 23, 2007 letter requesting clarification on thermal resistance testing required by new Appendix D to Part 178 of the Hazardous Materials Regulations (HMR; 49 CFR parts 171-180). The thermal resistance testing requirement was added to the HMR on January 31, 2007, under the Final Rule, "Transportation of Compressed Oxygen, Other Oxidizing Gases and Chemical Oxygen Generators on Aircraft (72 FR 4442), under Docket HM-224B. In addition, this Final Rule amended the HMR to: (1) require cylinders of compressed oxygen and other oxidizing gases and packages of chemical oxygen generators to be placed in an outer packaging that meets certain flame penetration and thermal resistance requirements when transported aboard an aircraft; (2) revise the pressure relief device (PRD) setting limit on cylinders of compressed oxygen and other oxidizing gases transported aboard aircraft; (3) limit the types of cylinders authorized for transporting compressed oxygen aboard aircraft; and (4) convert most of the provisions of an oxygen generator approval into requirements in the HMR.
In your letter, you state that both type CG-4 (a combination rupture disk/fusible plug device using a fusible alloy with a yield temperature not over 170 °F or less than 157 °F), and type CG-5 (a combination rupture disk/fusible plug device using a fusible alloy with a yield temperature not over 224 °F or less than 208 °F) pressure relief devices are currently authorized for use on oxygen cylinders in accordance with the Compressed Gas Association (CGA) Pamphlet S-1.1. You state that a temperature of 199 °F as specified in the thermal resistance testing method would melt the fusible metal in a CG-4 device, and would likely melt the fusible metal in a CG-5 device. You ask whether this is an acceptable test result.
Under your scenario, the melting of fusible metals in CG-4 and CG-5 pressure relief devices is an acceptable result during the thermal resistance testing specified in Appendix D to Part 178 of the HMR. A report entitled "Evaluation of Oxygen Cylinder Overpacks Exposed to Elevated Temperature" can be located in the public docket for HM-224B at www.dms.dot.gov
In your letter, you also state the instructions under Section 4 "Preparation for Testing" of Appendix D to Part 178 recommend that the cylinder be configured as when filled with a valve and pressure relief device. You state this scenario is not the configuration of the cylinder during transportation because a valve protection cap may be installed on the cylinder. You ask: (1) was it the intention that the cylinder be configured as when filled rather than as when transported; and (2) was it assumed, or determined through testing, that the absence of a transport cap would have a negligible effect on the results of the thermal resistance testing.
It is the intention of the HM-224B Final Rule that a cylinder being tested for thermal resistance be configured to most closely resemble conditions normally incidental to the transportation of hazardous materials. It was determined through testing that the absence of a transport cap would have a negligible effect on the results of the thermal resistance testing.
I hope this information is helpful.
Sincerely,
John A. Gale
Chief, Standards Development
Office of Hazardous Materials Standards
178. Appendix D