Interpretation Response #03-0159 ([Airgas, Inc.] [Mr. John Anderson])
Below is the interpretation response detail and a list of regulations sections applicable to this response.
Interpretation Response Details
Response Publish Date:
Company Name: Airgas, Inc.
Individual Name: Mr. John Anderson
Location State: WY Country: US
View the Interpretation Document
Response text:
Nov 5, 2003
Mr. John Anderson Reference No. 03-0159
Director of DOT Operations
Airgas, Inc.
P.O. Box 20067
Cheyenne, WY 82003
Dear Mr. Anderson:
This is in response to your telephone conversation with Sandra Webb of this office and subsequent letter, requesting a clarification of the requirements for filling DOT specification cylinders with non-liquefied (permanent) compressed gases under the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180).
You stated that it is industry practice to add approximately 50 psi to 100 psi to the target fill pressure so that, once the cylinder has cooled, the pressure in the cylinder at 70 of will be as close as possible to its marked service pressure. Specifically, you ask whether a high-pressure cylinder, such as a DOT 3A, 3AA or 3AL cylinder, may be filled in excess of its marked service pressure.
A cylinder may be filled to a pressure in excess of the marked service pressure to compensate for certain factors, such as heat of compression, high ambient temperature or changes in elevation. "However, § 173.301a(c) specifically states that when offered for transportation, the pressure in a cylinder at 21°C. (70 °F.) must not exceed the service pressure for which the cylinder is marked or designated, except as provided in § 173.302a(b) of the HMR. This requirement has been in effect for many years, and it is based on standards and recommendations of the compressed gas industry.
In your letter, you imply there is an inconsistency between fill limit requirements of the HMR and those of the U.S. Department of Health and Human Services' Food and Drug Administration (FDA). We disagree. FDA concurs with RSPA that the internal pressure at 21°C. (70 °F.) must not exceed the cylinder's service pressure. Therefore, your operating procedures must ensure that the marked service pressure is not exceeded when the cylinder is offered for transportation.
I hope this information is helpful. If we can be of further assistance, feel free to contact us.
Sincerely,
Edward T. Mazzullo
Director, Office of Hazardous
Materials Standards