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How Flammable Liquids are Categorized

May 2, 2020

A flammable liquid enjoys the attention of at least three different federal agencies: the DOT in matters of its transportation, OSHA as it might affect workplace safety, and the EPA concerning its cradle-to-grave management.

Add to that a gaggle of state, regional, and local authorities; and we feel compelled to begin this blog entry with our favorite caveat: get expert advice before deciding what to do with that rusting drum of stale gasoline out back.

Flammable vs. merely combustible

Flammable liquids ignite more readily than combustible ones. To wit, a flammable liquid can ignite at normal working temperatures. Combustible ones require higher than normal temperatures to catch fire, making them a lesser hazard.

A liquid is classified as “flammable” if it has a flashpoint at or below a given level, generally in accordance with the United Nations Globally Harmonized System of Classification and Labeling of Chemicals (GHA) criteria.

Per OSHA, that flashpoint is ? 199.4 °F. On the other hand, OSHA deems a liquid merely “combustible” if it has a flash point hotter than 199.4 F.

Flammable liquid categories

Both flammable and combustible liquids are considered Class 3 hazardous wastes by the EPA. OSHA and the GHS further subdivide flammable liquids into 4 categories according to their flashpoints and boiling points:[fusion_imageframe image_id=”13332|full” max_width=”” style_type=”” blur=”” stylecolor=”” hover_type=”none” bordersize=”” bordercolor=”” borderradius=”” align=”center” lightbox=”no” gallery_id=”” lightbox_image=”” lightbox_image_id=”” alt=”” link=”” linktarget=”_self” hide_on_mobile=”small-visibility,medium-visibility,large-visibility” class=”” id=”” animation_type=”” animation_direction=”left” animation_speed=”0.3″ animation_offset=”” filter_hue=”0″ filter_saturation=”100″ filter_brightness=”100″ filter_contrast=”100″ filter_invert=”0″ filter_sepia=”0″ filter_opacity=”100″ filter_blur=”0″ filter_hue_hover=”0″ filter_saturation_hover=”100″ filter_brightness_hover=”100″ filter_contrast_hover=”100″ filter_invert_hover=”0″ filter_sepia_hover=”0″ filter_opacity_hover=”100″ filter_blur_hover=”0″][fusion_separator style_type=”default” hide_on_mobile=”small-visibility,medium-visibility,large-visibility” class=”” id=”” sep_color=”#ffffff” top_margin=”5″ bottom_margin=”5″ border_size=”” icon=”” icon_size=”” icon_circle=”” icon_circle_color=”” width=”5″ alignment=”center” /]

And in case that high school chemistry class is just a faded memory:

The flashpoint is the lowest temperature at which something will ignite—if there’s a sauce of ignition. This is different from something called autoignition temperature, which is the point at which something will spontaneously ignite without an ignition source.

The boiling point is the temperature at which a liquid starts to vaporize, become a gas, and float into the atmosphere—a happenstance that will really annoy your local EPA guy or gal. (N.B. Not a good idea. Seriously.)

Both boiling points and flashpoints change with altitude and atmospheric pressure—so liquids might be more volatile if you’re living in Leadville vs. Calipatria.

Examples of commonly-used flammable liquids

  • Acetone—used as a solvent for plastics and synthetic fibers, thinning polyester resin, cleaning tools, as well as dissolving certain glues and epoxies
  • Toluene—used in paint thinners, nail polish removers, correction fluid (remember that stuff?), and let’s not forget: TNT aka dynamite
  • Diethyl ether—an erstwhile anesthetic nowadays contraindicated for its inconvenient propensity to ignite during surgery; it’s still used to make engine-starting fluid; it’s handy as a solvent in laboratories; and it can also be used as a recreational drug, albeit illegally
  • Alcohols—used as fuels and solvents, they include propanol, methanol, and ethanol, the last of which is the variety found in the adult beverage of your choice
  • Gasoline—use almost exclusively to annoy Prius and Tesla owners

Examples of commonly-used combustible liquids

  • Oils—such as automotive diesel, engine lubricant, and heating fuel
  • Acetic acid—most of which is used to produce vinyl acetate monomer (VAM), essential to paints, adhesives, packaging materials, and—yes—salad dressing (in vinegar)
  • Kerosene—widely used to power jet engines and some types of rockets when not being deployed to fire up the Weber. Factoid: globally, an estimated 500 million households still depend on fuels, particularly kerosene, to light up the joint
  • Linseed oil—extracted from flax seed; used as a preservative for wood and concrete; an ingredient in paints, varnishes, and stains; also used in soaps, inks, and linoleum
  • Ethylene glyco—used to make antifreezes, coolants, and HVAC heat-transfer fluids; this stuff also shows up in clothing, pillow, upholstery, and carpet polyesters. Oh… and we should mention bowling balls

EPA Rules

If yours is any kind of manufacturing enterprise, then it’s extremely likely that you’re using solvents that are considered either flammable or combustible by the EPA, and thereby require hazardous waste management for their storage and disposal.

Unfortunately, if confusion itself were hazardous waste, the EPA would have to consider itself an LQG.

Below in italics, we quote from the agency’s guidance entitled, Solvents in the Workplace—How to Determine if they Are a Hazardous Waste:

“Under the RCRA hazardous waste regulations, a solvent must first be classified as a solid waste before it can be considered for classification as a hazardous waste. Under RCRA, the term “solid waste” includes solid materials, liquids, and contained gases. Solvents are solid wastes when they are discarded or recycled in a certain manner, such as when burned for energy recovery. Solvents are considered solid wastes when they are:

  • “Spent” – contaminated through use and no longer able to be used for their intended purpose without first being regenerated, reclaimed, or otherwise reprocessed
  • Expired and can no longer be used
  • Off-specification commercial chemical products and can no longer be used
  • Unwanted and/or unused and destined for disposal
  • Residues, contaminated soil or water, or other debris resulting from the cleanup of a solvent spill”

Such guidance continues:

“If you are unsure if the solvents in your facility are solid wastes, you can use EPA’s Definition of Solid Waste Decision Tool v2, which walks you through a series of decisions to help you determine whether a material meets the definition of a solid waste.”

Sadly, clicking that link will send you to a page where “content is not maintained and may no longer apply.” In fact, there’s nothing there. The page just mocks you, saying that it’s “loading,” when it’s clearly doing no such thing. There’s nothing here, either.

So what to do?

Get expert advice, of course. But in the meantime:

  • Be sure to place spent flammable liquids in containers that are Factory Mutual (FM) or Underwriter Laboratory (UL) approved for the purpose.
  • Label containers immediately so that all personnel know the contents.
  • Keep containers out of traffic-flows and away from ignition sources.
  • Schedule regular pickups from a licensed and qualified hazardous waste management company.

Our advisors and field technicians stand ready to help you dispose of your flammable and/or combustible wastes safely, cost-effectively—and perhaps most importantly: in full compliance with federal, state, regional, and local requirements.

We’re here. And thank-you for reading our blog!

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Industries that commonly use combustible and/or flammable liquid solvents:

  • Adhesives manufacturing
  • Autobody repair
  • Automobile manufacturing
  • Circuit board manufacturing
  • Defense
  • Dry Cleaning
  • Electronics manufacturing
  • Electroplating
  • Fiber-reinforced plastics manufacturing
  • Film developing
  • Furniture manufacturing
  • Ink formulation
  • Metal fabrication
  • Metal finishing and plating
  • Paint manufacturing and use
  • personal care product manufacturing
  • Pharmaceutical manufacturing
  • Printing
  • Pulp and paper manufacturing
  • Rubber manufacturing
  • Semiconductor manufacturing
  • Wood staining and varnishing

Disposal of hazardous waste doesn’t have to be painful.