OSHA requirements are set by statute, standards and regulations. Our interpretation letters explain these requirements and how they apply to particular circumstances, but they cannot create additional employer obligations. This letter constitutes OSHA's interpretation of the requirements discussed. Note that our enforcement guidance may be affected by changes to OSHA rules. Also, from time to time we update our guidance in response to new information. To keep apprised of such developments, you can consult OSHA's website at http://www.osha.gov.

November 14, 1996

Mr. Bill Pollard
P.O. Box 2181
Pasco, Washington 99302

Dear Mr. Pollard:

This is in response to your letter which was faxed to our office on September 3, regarding compressed gas cylinders. We apologize for the delay in our response.

Your letter indicated the following: "An instrumentation trailer is to be relocated to remote sites and used intermittently. And then, it is returned to a central location and placed in a standby status for periods of one to several weeks. The trailer contains analytical chemistry instruments and two or three compressed gas cylinders."

"One 57" x 10" cylinder of compressed air, approximately 200 cubic feet capacity, is secured adjacent to a similar sized hydrogen cylinder. The cylinders each have site regulators and supply lines connected to analytical chemistry instruments."

Please find in the following your specific questions and our responses.

Q1: In inactive standby status the cylinders are "connected for use" but will not be in use until they are dispatched to the next job location. The "inactive standby" intervals will vary from one to several weeks. Should the hydrogen and/or compressed air cylinders be "placed into storage" (removed from the trailer) during standby, and if so, after what time has elapsed?

A1: The careful review of the Compressed Gas Association Pamphlet (P-1, 1965) revealed that for safe handling, cylinders that are not in use should be placed into storage. That is, when the cylinders are not in use, they should be capped for valve protection. It is suggested that during standby status, the regulators of the cylinders be removed. In addition, the cylinders should be securely attached to a fixed object to prevent the movement of the cylinders. Please refer to P-1, 1965, Section 3.3, "Storing Cylinders."

The provisions in that section are to prevent the accidental movement, discharge, etc., of the compressed gases. You did not indicate that any other activity takes place in the trailer. If that is so, adherence to the provisions in the pamphlet should make storage in the trailer acceptable, while the cylinders are not in use. We see no reason to remove the cylinders from the trailer, as long as unauthorized users are prevented from entering the trailer. Also, please note all safe handling procedures for storage of hydrogen in 29 CFR 1910.103, as well as all other provisions for compressed gases in P-1, 1965.

Q2: I understand that OSHA views breathing air cylinders the same as oxygen cylinders. If this interpretation is correct, is there an interpretive reference?

A2: It is not clear whether this question pertains to the integrity of the cylinders, as well as storage and handling procedures, or the quality of the air contained in the cylinders.

Please note that OSHA provides free compliance consultation through its area offices and for small employers, through state-run consultation services, and this may assist with questions to which we may be unable to respond due to lack of information, or on a need to see what is in place. Please call for further assistance with this question.

As you may know, the State of Washington administers its own occupational safety and health program under the state plan provisions of the Occupational Safety and Health Act of 1970. As part of that program, the state is required to have standards at "least as effective as" the federal standards; therefore, you should contact the state of Washington for information on its equivalent standard, if the workplace is in the state of Washington. In the state of Washington, you should contact the following:

Mark O. Brown, Director Washington Department of Labor And Industries General Administration Building P.O. Box 44000 Olympia, Washington 98504-4000 Telephone: (360)902-5495

Thank you for your inquiry. If you need further assistance, please contact Alcmene Haloftis of my staff at 202-219-8031.


John B. Miles, Jr., Director
Directorate of Compliance Programs