Mailing Flammable and Combustible Liquids That Do Not Sustain Combustion
UPDATED August 2010
This Customer Support Ruling (CSR)
describes the conditions under which certain flammable and combustible liquids that
do not sustain combustion are mailable when sent to domestic, non-APO/FPO/DPO, addresses.
Domestic Mail Manual (DMM) and Publication 52,
Hazardous, Restricted and Perishable Mail, define flammable or combustible
liquids based solely on their flash point.
Department of Transportation (DOT) and International Air Transport Association (IATA)
regulations allow shipping of these materials when they do not sustain combustion
as described below.
DOT regulations are found in Title
49 of the Code of Federal Regulations
(CFR). 49 CFR §173.120(a) defines a flammable
liquid as “a liquid having a flash point of not more than 60°C (140°F).
DOT lists several exceptions, among them “(3)
Any liquid with a flash point greater than 35°C (95°F) that does not sustain combustion
according to ASTM D 4206…or the procedure in Appendix H of this part” and “(5) Any
liquid with a flash point greater than 35°F (95°C) which is in a water-miscible
solution with a water content of more than 90 percent by mass.”
49 CFR §173.120(b)(1) defines a combustible liquid as “any liquid that does
not meet the definition of any other hazard class specified in this subchapter and
has a flash point above 60°C (140°F) and below 93°C (200°F).”
§173.120(b)(3) further states that a “combustible liquid that does not sustain
combustion is not subject to the requirements of this subchapter as a combustible
IATA Dangerous Goods Regulations
§ 18.104.22.168 provides that liquids “with a flash point exceeding 35°C (95°F) which
do not sustain combustion need not be considered as flammable liquids for the purposes
of these Regulations, if…they have passed a suitable
test for combustibility…or they are miscible solutions
with a water content of more than 90% by weight.”
Liquids that do not sustain combustion
may be mailed when the mailer presents a Material Safety Data Sheet (MSDS) that
indicates its composition as a water-miscible solution of more than 90% water and
the solution is unable to sustain combustion as indicated by standardized test ASTM
D 4206. These factors preclude the
liquid’s classification as a flammable liquid under both DOT and IATA
rules and define it as not subject to DOT requirements as a combustible liquid. After consideration of all the factors, the
liquid is properly classified as a non-regulated material by DOT standards and is
not subject to the restrictions for flammable or combustible liquids
liquids when it is mailed to domestic, non-APO/FPO/DPO, addresses.
The material is still subject to the general packaging requirements for
liquids in DMM 601.1 through 601.8 and in Publication 52,
Hazardous, Restricted, and Perishable Mail, 226, 462, and 463.