ISOTECH Laboratories, Inc. — Hazardous Materials Safety Interpretation

Page 1U.S. Department of Transportation Washington, D.C. 20590 400 Seventh Street, S.W. Pipeline and Administration Hazardous Materials Safet APR 3 2007 Mr. Dennis Coleman ISOTECH Laboratories, Inc. President Ref. No. 06-0283 Champaign, IL 61821-1826 1308 Parkland Court Dear Mr. Coleman: mixture of natural gas containing a hydrogen sulfide (HS) concentration level not This responds to your letter dated December 21, 2006 regarding whether a sample exceeding 14% (on a molar basis) may be transported by all modes of transportation without labeling the sample toxic inhalation hazard. Isotech Laboratories, Inc. (Isotech) analyzes natural gas samples for commercial containing small amounts of HS. Based on your review of the Class 2 assignment of consumers located in the United States and abroad. Samples are shipped to Isotech hazard zones in §173.116(a) and your calculations according to §173.133(b)(1), you determined that the concentration level of HS in a mixture of natural gas could reach 14% (on a molar basis) before being considered toxic-by-inhalation and requiring a 2.3 (Poison Gas) label. Specifically, you ask whether your calculated concentration level is H›S concentration not exceeding 14% (on a molar basis) classed as Division 2.1 correct; thus, allowing Isotech and its customers to ship natural gas samples containing an (Flammable Gas) and not Division 2.3 (Poison Gas), which is toxic-by-inhalation, requiring display of a POISON GAS label. Under the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180), it is a shippers responsibility to classify a hazardous material (See §173.22). This Office does provided, it is our opinion that a sample mixture of natural gas containing a hydrogen sulfide (H,S) concentration level not exceeding 14% (on a molar basis) may be 173.11 (a) 173.22 173.116 060283 173133(6)(1)#

Page 2transported by all modes of transportation as a Division 2.1 (Flammable Gas) material without labeling the sample toxic inhalation hazard. I hope this satisfies your inquiry. If we can be of further assistance, please contact us. Sincerely, Pantone f Chief, Standards Development Office of Hazardous Materials Standards#

Page 3Engrum $172.701 AlISOTECH $ 173.115 §173.114 www.isotechlabs.com mail@isotechlabs.com Isotech Laboratories, Inc. 1308 Parkland Court Champaign, IL 61821-1826 Telephone 217/398-3490 FAX 217/398-3493 December 21, 2006 Applicability 06-0283 Via UPS Next Day Air Office of Hazardous Material Standards Attn: PHH-10 Pipeline and Hazardous Materials Safety Administration 400 7th Street, S.W. U.S. Department of Transportation Washington, D.C. 20590-001 Re: Permissible Non-toxic Hydrogen Sulfide Concentrations Dear Sir or Madam: consumers located in the United States and abroad.! Isotech seeks PHMSA's confirmation that Isotech Laboratories, Inc. ('Isotech") analyzes natural gas samples for commercial a sample mixture of natural gas containing a hydrogen sulfide ("H¿S") concentration level not exceeding 14% (on a molar basis) may be transported on all modes of transportation without labeling the sample as a toxic inhalation hazard. reviewed the HAZMAT regulations and noted that HS, in its pure form and at specific On occasion, samples are shipped to Isotech containing small amounts of HaS. We require 2.3 labeling as a toxic inhalation hazard.? We then set out to determine what concentration levels, is considered a division 2.3 gas poisonous by inhalation and thus would concentration of HS would be permissible for transport, without 2.3 labeling, under all modes of transportation, assuming the quantity limitations of 49 CFR $172.101 columns 9(A), 9(B), and 10 were met. Based on our review of the Class 2 assignment of hazard zones (§173.116(a)) and our calculations per 49 CFR §173.133(b)(1), we determined that the concentration level of H_S in mixture of natural gas could reach 14% (on a molar basis) before being considered toxic an herefore, requiring class 2.3 labeling. Although we have received tentative verbal confirmatio from a PHMSA chemist that our calculated concentration level is correct, out of an abundance of caution we seek PHMSA's written confirmation that: Isotech and its customers may ship natural gas samples containing an H2S concentration not exceeding 14% (on a molar basis) as Flammable Gas, 1 See www.isotechlabs.com. 2 See 49 CFR S§173.115, 172.416.#

Page 4Office of Hazardous Material Standards December 21, 2006 Page 2 sample as a toxic inhalation hazard. Class 2.1, on all allowable modes of transportation without labeling the you have any questions or require additional information, please do not hesitate to contact me We thank you in advance for providing us with the above-requested confirmation. If at the above-listed number. Very truly yours, die meltilina. President Dennis D. Coleman İsotech Laboratories, Inc. 1308 Parkland Court Champaign, IL 61821-1826 Telephone 217/398-3490 FAX 217/398-3493#