If you are a company that handles flammable liquids, it’s critical to know how these liquids are classified so that you can take the proper precautions when storing and transporting these materials.  

What class is flammable liquids in? The National Fire Protection Association (NFPA) classifies all flammable liquids as Class I. However, based on the risk of fire, these liquids are sub-classified, with six main sub-classifications.


How The Classification System Works


what class is flammable liquids inThe NFPA classification system is based on a liquid’s flash point. A flash point is, “the lowest temperature at which a substance generates a sufficient amount of vapor to form a vapor/air mixture that can be ignited.”  

Flammable liquids have a flash point under 100 degrees. Combustible liquids have a flashpoint at or above 100 degrees F. The lower the flash point, the easier the vapors of the liquid will ignite. 

What’s the difference between flammable and combustible? Flammable liquids will catch on fire and easily burn at normal working temperatures. Combustible liquids need heat before they can ignite.  

Important Note: Guidelines may vary, which is why it is important to check all local, state and federal regulations to make sure you are meeting each of them. For example, according to Resource Conservation and Recovery Act regulations, the regulatory cutoff for D001 ignitable liquids is 140 degrees F. D001 is the EPA characteristic waste code that designates a waste stream as ignitable. 


How The Classification System Breaks Down


Although flammable liquids fall under Class 1, there are several sub-classifications for both flammable and combustible liquids.  

Flammable Liquids Combustible Liquids
Class IA Class III
           - Flash points 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, motor oil, kerosene
           - Unstable flammable liquids also fall                             under this classification Class IIIA
           - Examples include Ethylene oxide,                                pentane, propylene oxide, vinyl                            chloride           - Flash point at or above 140 degrees F,                       but below 200 degrees F
Class IB           - Examples include formaldehyde,                                 creosote oil, linseed oil, mineral oil
          - Flash points below 73 degrees F Class IIIB
          - Boiling points at or above 100 degrees F           - Flash point at or above 200 degrees F

          - Examples include acetone, ethyl                                   alcohol, isopropyl alcohol, benzene,                     octane, methanol, heptane

          - Examples include castor oil, coconut oil,                     fish oil, olive oil, ethylene glycol,                           glycerine
Class IC  
           - Flash points at or above 73 degrees F,                        but below 100 degrees F  
          - Examples include diethylene glycol,                             turpentine, xylene, isobutyl alcohol,                     mineral spirits  

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


Fire Class Flammable Liquids Fall Under


The NFPA’s classification of flammable liquids is often confused with which classification of fires flammable liquids fall under. 

The NFPA also classifies fires in five different ways. They are classified depending on what is fueling the fire.  

  • Class A fires are fueled by common combustibles like wood and paper.
  • Class B fires are fueled by flammable liquids such as gasoline and gases like propane.
  • Class C fires involve energized electrical equipment such as motors and appliances.
  • Class D fires occur in combustible metals like magnesium and titanium.
  • Class K fires are fueled by cooking oils and greases. 

You can read more about what types of liquids Class B includes, as well as how to respond to a fire should one occur, in our article, Which Class Of Fires Consists Of Flammable Liquids?


How Class Determines Storage Requirements


Storing flammable liquids must be done with careful thought and consideration. For each sub-classification of flammable and combustible liquids, there may be additional requirements. 

For example, the state of California has specific requirements for the container size and quantities of flammable and combustible liquids allowed in a laboratory for each sub-classification. A glass container, for instance, can hold 1 pint of a Class IA liquid. However. That same size of container can hold 1 gallon of a Class II liquid. 

Here are a few other considerations to keep in mind when storing flammable liquids: 

  • Where they are stored: Storage containers should always be well out of the way, never blocking entrances, stairwells or doorways. They should also be away from any ignition sources. Most local regulations require that flammable liquids are stored in a fire-proof storage cabinet and that all containers are sealed as well. 
  • How they are labeled: Labeling is extremely important because it alerts employees and transporters which liquids are inside containers and if there are any associated dangers. Labels should include:
    • The start date of accumulation of waste
    • The type of liquid
    • Any additional information mandated by your state/local authorities 
  • If all other best practices are met: These include whether thorough documentation is in place should an emergency occur, whether incompatible flammable liquids are separated, whether inspections regularly occur and if all staff is properly trained on handling hazardous waste.


How To Dispose Of Class I Flammable Liquids


Because of the inherent dangers flammable liquids pose, it’s important for any company that routinely utilizes this form of hazardous waste to have a proper disposal plan in place.  

Hazardous waste disposal codes often dictate how a material should be disposed of, but your overall disposal plan should also include a partnership with a company that will routinely accept your particular waste. 

When it comes to flammable liquids, that may mean partnering with a company like Temarry Recycling that recycles solvents. 

At Temarry, which operates in Southern California and has a state-of-the-art recycling facility just across the U.S.-Mexico border, the solvent distillation process is part of a Closed Loop Recycling system. This keeps materials at their highest value and ensures nothing is wasted.


Here’s how it works: 

A waste to energy process begins the loop. 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 is quenched and falls 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 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.  

Finally, 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. 

Closed Loop Recycling offers many benefits to companies, from the cost advantage of not having to send your waste a far distance to improved liability and enhanced corporate sustainability.


A Full Picture


If your company regularly handles flammable liquids as part of its everyday operations, it is critically important to understand how each liquid is classified so that you are better equipped to safely manage this hazardous waste.  

However storage is just one important piece of properly managing any flammable liquids on-site. What happens to that waste once it leaves your facility plays a role in the full picture of how your company prioritizes sustainability and its long-term outlook. 

Recycling your solvents at a facility like Temarry Recycling offers several advantages for companies that are looking for ways to improve their sustainability plans, from reducing your reliance on natural resources and keeping materials at their highest utility always, to reducing the amount of waste you must dispose of and therefore reducing any associated costs with that disposal.  

Our article, 7 Facts You Need To Consider In The Disposal Of Flammable Liquids, offers more information about why the proper disposal of flammable liquids is critical in industry today, as well as what actions you can put in place to ensure all regulations are being met.


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