Flammable liquids are those that have a flashpoint of under 100 degrees F. Combustible liquids, on the other hand, have a flash point at or above 100 degrees.  

What is a flash point? A flash point is the lowest temperature at which a liquid generates enough vapor to form a vapor and air mixture that can be ignited.  

The lower the flash point, the easier the vapors of the liquid will ignite. 

Knowing the flash point of flammable liquids is essential to ensuring these substances are properly stored so that fires can be prevented and the workplace remains as safe as possible. 


Flammable Liquids Classification


The National Fire Protection Association (NFPA) classifies all flammable liquids as Class 1. This class is then broken down into six categories, known as sub-classifications, based on the risk of fire.  

The six flammable liquids categories are:

  1. Class IA
  2. Class IB
  3. Class IC
  4. Class II
  5. Class IIIA
  6. Class IIIB 

Flammable and combustible liquids are categorized based on their flashpoints.

Flammable Liquids Combustible Liquids
Class IA Class II
- Flashpoints below 73 degrees F - Flash point at or above 100 degrees F, but below  140 degrees F  
- Boiling points below 100 degrees F - Examples include camphor oil, diesel fuel, pine tar, kerosene

- Unstable flammable liquids also fall under this classification  
- Examples include Ethylene oxide, pentane, propylene oxide, vinyl chloride  
Class IB Class IIIA
- Flashpoints below 73 degrees F - Flash point at or above 140 degrees F, but below 200 degrees F
- Boiling points at or above 100 degrees F - Examples include formaldehyde, creosote oil, linseed oil, mineral oil
- Examples include acetone, ethyl  alcohol, isopropyl alcohol, benzene, octane, methanol, heptane  
Class IC Class IIIB
- Flash points at or above 73 degrees F, but below 100 degrees F - Flash point at or above 200 degrees F
- Examples include diethylene glycol, turpentine, xylene, isobutyl alcohol, mineral spirits - Examples include castor oil, coconut oil, fish oil, olive oil, ethylene glycol, glycerine


Source: NFPA


Note: According to the NFPA, because Class IA liquids are so volatile, boiling points are used only to distinguish between IA and IB. 

Local and state guidelines may vary based on flash points, however, which is why companies that handle flammable liquids should always check all regulations that they may be subject to while operating.  

Even federal guidelines may vary depending on the agency. For example, the Resource Conservation and Recovery Act also includes guidelines that slightly differ from the ones above. 


Flammable Liquids Storage Guidelines


If your workplace uses flammable liquids as part of your manufacturing process, it is important to know how these substances should be safely stored. A liquid’s flash point impacts the size of container you are permitted to use, as well as how much of the substance you are allowed to store. 

In the state of California, companies must use specific container sizes for storing flammable and combustible liquids in laboratories. In the table below, the amount of liquids that is allowed to be stored in glass, metal, OSHA-compliant safety cans and metal drums differs based on the NFPA classification system (which is based on flash point).

Source: UC San Diego


A liquid’s flash point also impacts the maximum quantity of that liquid allowed under California Fire Code, which is outlined in the table below.  

 Source: UC San Diego      


Other Guidelines For Safe Storage And Disposal


Even when meeting container and maximum quantity requirements, thereflammable liquids are those that have a flashpoint of are still several other measures a company should take to ensure the safe storage of flammable liquids.  

Below are three important tips that should be part of every safety plan:

  1. Never block stairwells or exits with containers filled with flammable liquids.

  2. Store flammable liquids in safe, secure locations such as in fire-proof storage cabinets.

  3. Properly label each container with information like accumulation start date, name of liquid, a hazardous waste logo and your company’s information in case of an emergency. 

Finally, it’s important to keep in mind that while you may need to store flammable liquids onsite, doing so can pose several risks. It’s always better to dispose of your flammable liquids if they are no longer needed to keep your workplace and community safe.  

If your company is looking for a disposal option that is more sustainable and cost-effective, closed loop recycling provides a state-of-the-art method for accomplishing both.  

Temarry Recycling operates a recycling facility just across the U.S.-Mexico border where spent solvents are recycled through a solvent distillation process. This closed loop process keeps materials at their highest value and ensures nothing is wasted … offering companies the highest level of sustainability. 

The closed loop recycling system begins with a waste to energy process in which organic solids with >5000 BTU are converted to steam. Waste is fed by a conveyor into the primary stage for thermal destruction at 1500 degrees F. All vapors and gases are then directed to secondary thermal treatment at 1500 degrees F.  

Inorganic solids, or ash, from the primary stage are quenched and fall into an ash hopper. Heat is then directed to a 200-horsepower steam generator. The remaining gases are directed to a modern two-stage venturi scrubber to ensure that only clean water vapor is emitted into the atmosphere.  

The solvent distillation process begins next. Using the steam from the waste to energy process as energy to power the recovery stills, spent solvents are re-manufactured and sold back into industry for their original solvent properties.  

A water treatment process is needed to close the loop. The water treatment process extracts usable water from industrial hazardous wastes. In turn, treated water is used on site for industrial needs, including the waste-to-energy equipment and a cooling tower.   

Partnering with Temarry Recycling can provide many benefits for companies that use flammable liquids, especially those located on the West Coast:

  • Substantial money saved in transportation costs since companies do not have to transport their wastes to the nearest cement kilns in the Midwest

  • Lowered carbon footprint since less fuel is required for transportation

  • Reduction in cradle to grave liability since Temarry assumes liability at the U.S.-Mexico border. 

Flammable liquids can be extremely dangerous for any company that uses them onsite. Knowing their flashpoints is the first step to ensuring safe storage onsite. However, what a company does with their flammable and combustible liquids once they are no longer needed can make a greater impact on the community and environment.  

That’s where Temarry comes in and allows companies to leave a smaller footprint on the community they serve.

Are you Recycling or Fuel Blending

Larry Burton

Larry Burton

Larry Burton has over 25 years of experience in the hazardous waste and chemical industries. He has worked for several major corporations, including Honeywell, and can speak on a variety of industry-related topics. He has specialized knowledge in Circular Economy, Solvent Distillation, Closed Loop Recycling Technology, Waste to Energy, and the H061 Paradigm. Larry has extensive knowledge of the latest technologies that allow businesses to explore real-world sustainable solutions. These solutions will help reduce their carbon footprint and improve their profitability. Larry is currently the CEO of Temarry Recycling.

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