In general, there are two ways in which a material may be classified as a Combustible Liquid (Hazard Class 3) pursuant to the regulations of the PHMSA/USDOT; they are:
- It does not meet the definition of any other hazard class and its flash point is above 60 °C (140 °F) and below 93 °C (200 °F).
- It meets the definition of a Flammable Liquid with a flash point of ≥100˚F and ≤140˚F and the shipper elects to classify it as a Combustible Liquid.
Read more about both of these options here: The Classification of a Flammable Liquid and a Combustible Liquid
The transportation in commerce of a Combustible Liquid presents an interesting option when determining the placards to display on a motor vehicle or rail car.
If the identification number of the HazMat is not displayed on the Combustible Liquid placard when transporting a Combustible Liquid by highway or rail, then the placard must comply with 49 CFR 172.544(a), which reads:
§172.544 COMBUSTIBLE placard.
(a) Except for size and color, the COMBUSTIBLE placard must be as follows:
The situation becomes more complex if the Combustible Liquid placard is used to display the identification number for the hazardous material. If that is the case, then the placard must comply with 49 CFR 172.332(c)(4), which reads:
For a COMBUSTIBLE placard used to display an identification number, the entire background below the white background for the identification number must be white during transportation by rail and may be white during transportation by highway.
So, for a Combustible Liquid placard used to display the identification number in transportation by rail, the entire background below the white background for the identification number must be white.
However, for a Combustible Liquid placard used to display the identification number in transportation by highway, the entire background below the white background for the identification number may be white.
In other words, the appearance of the placard that is required for rail transportation is an option for transportation by highway.
Further, if the white bottom Combustible Liquid placard is used, then compliance with §172.544(b) is required, “On a COMBUSTIBLE placard with a white bottom as prescribed by §172.332(c)(4), the class number must be red or black.
This PHMSA letter of interpretation (10-0182) clarifies the use of the Combustible Liquid placard displaying the identification number and provide several examples of acceptable v. unacceptable placards.
If you’re involved in the transportation of a Combustible Liquid, make certain that your use of the hazard communication methods (placards are one of the four) is correct.
Please contact me if you have any question about the transportation of hazardous materials or if you wish for a free consultation on your requirement to provide initial and triennial training for your HazMat Employees.
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