The United States Pipeline and Hazardous Materials Safety Administration (“PHMSA”) addressed in a May 6 interpretive letter whether certain residue is subject to the Hazardous Materials Regulations (“HMR”).
PHMSA was responding to a September 24, 2019 letter from Entegris, Inc. (“EI”) requesting clarification of the HMR applicable to the empty packaging provisions.
Entegris asked whether:
… a 50-liter Department of Transportation (“DOT”) 3AA – 2400 specification cylinder containing “UN 2199, Phosphine, 2.3 (poisonous gas), 2.1 (flammable gas)” residue is subject to the HMR after the cylinder is cleaned of residue and purged of vapors using a vacuum pump and nitrogen purging.
Entegris stated that the 100 ppmv phosphine/nitrogen mixture within the cylinder has a calculated LC50 of 200,000 ppm and the pressure within the cylinder is less than 200 kPa at 68 degrees Fahrenheit.
The company sought confirmation that the gas mixture is not subject to the HMR.
PHMSA reminds Entegris that it is the responsibility of the shipper to classify hazardous materials.
Nevertheless, the PHMSA concurs that a phosphine/nitrogen mixture within a cylinder that has calculated LC50 of 200,000 ppm and a pressure less than 200 kPa does not meet the definition of a Division 2.1 or Division 2.3 material to HMR.
Cited are paragraphs (b)(2)(ii) and (iii) of § 173.29 which states:
… a packaging that is sufficiently cleaned of residue and purged of vapors to remove any potential hazard, or that is refilled with a material that is not subject to the HMR to the extent that any residue that remains in the packaging no longer poses any hazard, is not subject to the requirements of the HMR.
A copy of the letter can be downloaded here.
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