PHMSA Response Letter

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Mr. Chris W. Gibson
EHS&R Manager
Hawkins, Inc.
3100 East Hennepin Avenue
Minneapolis, MN 55413

Ref. No.: 08-0027

Dear Mr. Gibson:

This is in response to your January 22, 2008 letter requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) applicable to cylinders. Your scenario involves the loading requirements for a highway shipment of cylinders in accordance with § 177.840(a)(1). Specifically, you ask if a cylinder not equipped with a pressure relief device and filled with anhydrous ammonia may be loaded in a horizontal position. Anhydrous ammonia may be offered for domestic transportation as a Division 2.2 material or, otherwise, as a Division 2.3 material.

The answer is yes. The last sentence in § 177.840(a)(1) specifies “a pressure relief device, when installed, must be in communication with the vapor space of a cylinder containing a Division 2.1 (flammable gas) material.” This provision does not apply to a cylinder not equipped with a pressure relief device or a cylinder not containing a Division 2.1 material. Therefore, the cylinders you describe may be transported in a horizontal position.

I hope this information is helpful. If you have further questions, please do not hesitate to contact this office.

Sincerely,

Hattie L. Mitchell
Chief, Regulatory Review and Reinvention
Office of Hazardous Materials Standards

177.840(a)(1)