Flammable liquid

Flash Point for Classification of US DOT Flammable and Combustible Liquids

Flash Point is a term used by the US EPA when characterizing an Ignitable Hazardous Waste and the US DOT when classifying a Flammable or Combustible Liquid.  Though similar, there are differences in how these two Federal agencies define and describe this term.  If you work with solvent, inks, paints, resins, fuels, or many other organic hydrocarbons it is necessary for you to be familiar with how both the US DOT and the US EPA identify this term and its role in identifying a hazardous material or a hazardous waste.  The purpose of this article is to describe the use of the Flash Point for classifying a Flammable or Combustible Liquid per the regulations of the US DOT.  You may also be interested in the US EPA’s use of Flash Point for the Determination of a Characteristic Ignitable Liquid Hazardous Waste.

The US DOT defines Flash Point at 49 CFR 173.120(c)(1):  “Flash Point means the minimum temperature at which a liquid gives off vapor within a test vessel in sufficient concentration to form an ignitable mixture with air near the surface of the liquid.”  It goes on to describe the methods to determine Flash Point based on the characteristics of the sample:

1.  For a homogeneous, single-phase, liquid having a viscosity <45 S.U.S. at 38°C (100°F) that does not form a surface film while under test, one of the following test procedures shall be used:

    • Standard Method of Test for Flash Point by Tag Closed Cup Tester, (ASTM D 56) (IBR; see §171.7 of this subchapter).
    • Standard Test Methods for Flash Point of Liquids by Small Scale Closed-Cup Apparatus, (ASTM D 3278) (IBR; see §171.7 of this subchapter).
    • Standard Test Methods for Flash Point by Small Scale Closed Tester, (ASTM D 3828) (IBR; see §171.7 of this subchapter).

2.  For a liquid other than one meeting all the criteria of #1 above, one of the following test procedures must be used:

    • Standard Test Methods for Flash Point by Pensky-Martens Closed Cup Tester, (ASTM D 93) (IBR; see §171.7 of this subchapter).  For cutback asphalt, use Method B of ASTM D 93 or alternative tests authorized in this standard.
    • Standard Test Methods for Flash Point of Liquids by Small Scale Closed-Cup Appartus (ASTM D 3279) (IBR; see §171.7 of this subchapter).
    • Determination of Flash/No Flash – Closed Cup Equilibrium Method (ISO 1516) (IBR; see §171.7 of this subchapter).
    • Determination of Flash Point – Closed Cup Equilibrium Method (ISO 1523) (IBR; see §171.7 of this subchapter).
    • Determination of Flash Point – Pensky-Martens Closed Cup Method (ISO 2719) (IBR; see §171.7 of this subchapter).
    • Determination of Flash Point – Rapid Equilibrium Closed Cup Method (ISO 3679) (IBR; see §171.7 of this subchapter).
    • Determination of Flash/No Flash – Rapid Equilibrium Closed Cup Method (ISO 3680) (IBR; see §171.7 of this subchapter).
    • Determination of Flash Point – Abel Closed-Cup Method (ISO 13736) (IBR; see §171.7 of this subchapter).

3.  If the liquid is a mixture of compounds with different volatility and Flash Points (eg. mixed solvents and paint), its Flash Point must be determined by one of the methods in #’s 1 & 2 above on the material in the form in which it is to be shipped.  Note that the form it is to be shipped in may differ from the form in which is was received as product or its form at its point of generation as a hazardous waste.  If by this test the Flash Point is greater than -7°C (20°F), then a second test shall be made by the procedure described in §173.120(c)(2) which is too complicated for me to describe here.

4.  And one final thing:  for Flash Point determinations by Setaflash closed tester, the glass syringe specified need not be used as the method of measurement of the test sample if a minimum quantity of 2 mL (0.1 oz) is assured in the test cup.

These are just the regulations of the US DOT pertaining to the determination of one class of hazardous material:  Flammable and Combustible Liquids.  There are many more, and you must be familiar with all of them if you ship or receive hazardous materials in any quantity, including hazardous waste.  My one day of training addresses the regulations of both the US DOT and the US EPA, it will help you to properly classify your hazardous materials and identify your hazardous waste.  Contact me to schedule the right kind of training for you.

Flammable and Combustible Liquid Hazardous Materials

Both Flammable and Combustible Liquids are Class 3 hazardous materials defined and described by the USDOT/PHMSA at 49 CFR 173.120.  Too often, this type of hazardous material is assumed to be the same as a USEPA hazardous waste with the characteristic of ignitability (D001).  Though similar in many respects, the terms originate from different federal agencies and have differing determination criteria.  The purpose of this article is to identfiy and describe both a Class 3 Flammable Liquid and a Class 3 Combustible Liquid as defined and regulated by USDOT/PHMSA.

For more information about ignitable hazardous waste read: US EPA Determination of an Ignitable Liquid as a Hazardous Waste.

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A Flammable Liquid “means a liquid having a flash point of ≤60°C (140°F), or any material in a liquid phase with a flash point ≥37.8°C (100°F) that is intentionally heated and offered for transportation or transported at or above its flash point in a bulk packaging…”

So, to meet the definition of a Class 3 Flammable Liquid it must be…

  1. A liquid with a flash point of ≤60°C (140°F), or;
  2. Any material with a flash point ≥37.8°C (100°F), that is…
    • Intentionally heated and offered for transportation, or;
    • Transported at or above its flash point in a bulk packaging.

Even if matching the above description, the following materials are exempt from definition as a Flammable Liquid:UN1993 in Intermediate Bulk Container

  1. Any liquid meeting one of the definitions of a Class 2 (Divisions 2.1, 2.2, & 2.3) compressed gas at 49 CFR 173.115.
  2. Any mixture having one or more components with a flash point ≥60°C (140°F), that make up at least 99% of the total volume of the mixture, if the mixture is not offered for transportation or transported at or above its flash point.
  3. Any liquid with a flash point >35°C (95°F) that does not sustain combustion according to ASTM D 2406 (IBR, see §171.7 of this subchapter) or the procedure in appendix H of this part.
  4. Any liquid with a flash point >35°C (95°F) and with a fire point >100°C (212°F) according to ISO 2592 (IBR, see §171.7 of this subchapter).
  5. Any liquid with a flash point >35°C (95°F) which is in a water-miscible solution with a water content of more than 90% by mass.

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A Combustible Liquid “means any liquid that does not meet the definition of any other hazard class specified in this subchapter and has a flash point >60°C (140°F) and <93°C (200°F).”

So, to meet the US DOT definition of a Class 3 Combustible Liquid it must…

  1. Not meet the definition of any other US DOT hazard class, and;
  2. Be a liquid with a flash point >60°C (140°F) and <93°C (200°F).

In some cases, the US DOT will allow you to reclassify a Flammable Liquid as a Combustible Liquid to take advantage of the reduced regulatory burden when transporting Combustible Liquids.

Contact me with any questions you may have about the transportation of hazardous materials by air, highway, vessel, or rail

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Whether it’s a Flammable Liquid, Combustible Liquid, or liquid Ignitable hazardous waste it is your responsibility to keep them straight and to determine if you are subject to their unique regulations when handling or transporting them.

US DOT Exception for Combustible Liquid Hazardous Materials

You may be familiar with several hazardous materials such as diesel fuel or kerosene that, depending on their formulation, may have a slightly higher flashpoint than more obvious flammable liquids such as gasoline.  However, you may not be aware of the exclusion from full regulation that is allowed for these high-flash materials and how it may be of use to you.

A combustible liquid is defined at 49 CFR 173.120(b)(1) as any liquid that does not meet the definition of any other hazard class and has a flash point of >60˚C (>140˚F) and <93˚C (<200˚F).  A flammable liquid is defined at 49 CFR 173.120(a) as a liquid with a flash point ≤60˚C (≤140˚F), or any liquid in bulk packaging with a flashpoint ≥37.8˚C (≥100˚F) that is intentionally heated and transported above its flashpoint (some exceptions).

There are great advantages to shipping a hazardous material as a combustible liquid instead of as a flammable liquid which will be addressed later.  However, what are you to do if the flashpoint of your hazardous material is ≤60˚C (≤140˚F), thus making it a flammable liquid by definition?  Do you have no choice but to ship it as a flammable liquid?  Not necessarily; there is a regulatory exemption [see 49 CFR 173.150(f)] that allows you to reclassify and ship a flammable liquid as a combustible liquid.  To do so, your flammable liquid must meet the following conditions:

  • Doesn’t meet the definition of any other hazard class.
  • To be transported within the U.S. only.
  • Has a flashpoint of ≥100˚F and ≤140˚F. Click here for an illustration of these temperature ranges.
  • To be transported by rail or highway.
  • Is not a flammable liquid that is also an elevated temperature material that has been intentionally heated and is transported above its flashpoint.

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If you are able reclassify your flammable liquid as a combustible liquid, you must research further to see which of the two following options are available to you.

Option 1:

If the combustible liquid is in a non-bulk package and is not a hazardous waste, hazardous substance, or marine pollutant; then it is not subject to any of the Hazardous Materials Regulations.

Option 2:

If the combustible liquid is in a bulk package or is a hazardous waste, hazardous substance, or marine pollutant; then it is still subject to the following requirements of the HMR:

  • Shipping papers.
  • Markings.
  • Placarding (if in bulk only).
  • Incident reporting.
  • The general packaging requirements of 49 CFR 173, Subpart B.
  • Triennial HazMat Employee training.
  • Emergency response information.

The only exceptions allowed in Option 2 then are those for package labeling and security plans, not as good as option 1, but better than nothing.

Contact me with any questions you may have about the transportation of hazardous materials by air, highway, vessel, or rail

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Perhaps the combustible liquid exemption may be suitable for your operations, perhaps not.  If you are able to reclassify your flammable liquid to a combustible liquid and then use Option 1, you will see a significant reduction in your regulatory requirements and related costs.  In any event, knowing about this exemption and others can provide you with a more complete knowledge of the Hazardous Material Regulations.