Carlton W. Hendrix, Jr — Hazardous Materials Safety Interpretation

Page 1of Transportation U.S. Department 400 Sevonth St., S.W. Special Programs Research and Washington, D.C. 20590 Administration JUL 1 - 2002 Mr. Carlton W. Hendrix, JI. 230 Ellenwood Drive Ref No. 02-0140 Canton, GA 30115-8276 Dear Mr. Hendrix: This is in response to your May 1, 2002 letter requesting interpretation of the Hazardous Materials Regulations (HMR; 49 CFR Parts 100-185) applicable to open valves on cargo tanks. Specifically, you question the practice of some transporters of non-flammable, compressed gases leaving a valve, located between the pump and the cargo tank's hose connection, slightly open on transports with a capacity greater than 3500 water gallons. Per your letter, the purpose of this practice is to allow any excess pressure that builds up in the 2 inch "wet" hose to return to the cargo tank through the bypass feature of the internal valve. As provided in § 177.840(g) each liquid discharge valve on a cargo tank motor vehicle, other than an engine fuel line valve, must be closed during transportation except during loading and unloading. This means each discharge valve in a liquid discharge system must be closed during transportation. This requirement does not pertain to any intermediate isolation valves that may be present in a liquid discharge system. The main internal valve and delivery hose end valve must be closed while in transport. You are not required to close any other valves in the system. I hope this information is helpful. If we can be of further assistance, do not hesitate to contact us. Sincerely, When A lis Delmer F. Billings Chief, Standards Development Office of Hazardous Materials Standards#

Page 2• • : 230 Ellenwood Drive Canton, GA 30115-8276 Foster May 1, 2002 Mr. Thomas G. Allen §177.840 (9) Senior Transportation Regulations Specialist Office of Hazardous Materials Standards Cargo Tanks U.S. Department of Transportation 02-0140 400 Seventh Street, S. W. Washington, D.C. 20590 Dear Sir: I have a question concerning the requirements found in 49 CFR 177.840, (g). It states "Each liquid discharge on a cargo tank, other than an engine fuel line valve, must be closed during transportation except during loading and unloading" There are some transporters of non-flammable, compressed gases that are leaving the valve, located between the pump and the cargo tank's hose connection, slightly open on transports with a capacity greater than 3500 water gallons. The purpose of this is to allow any excess pressure that builds up in the 2 inch "wet" hose to return to the cargo tank through the bypass feature of the internal valve. It is my belief that this practice is contrary to the requirement found in 177.840(g). Please advise if I am correct in my interpretation of the regulations so I can advise my clients. Sincerely, Canton W. Hendrix, fo. Carlton W. Hendrix. Jr. ....#

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Page 45/22/02 Del, calla Ma Pendin to confirm that he is sefessing ta a liquid discharge sore, and not an intermediate isolation volve He confirmed chis inquiry pestains its a liquid discharge value onlap. Thanks, Alean#

Page 5METRO * 238 Ellenwood Drive .. W. Hendrix, Jr. C: MAY cit Canton, GA 30115-8276 Mr. Thomas G. Allen Senior Transportation Regulations Specialist Office of Hazardous Materials Standards ! U.S. Department of Transportation 400 Seventh Street, S.W. Washington, D.C. 20590 20530+0003 ...!#