Is ethanol a class 1 flammable liquid?

In this blog post, we will answer the question, “is ethanol a class 1 flammable liquid?”. We will also discuss what ethanol is, the flashpoints of ethanol in various concentrations, and classifications of flammable liquid according to NFPA and OSHA.

Is ethanol a class 1 flammable liquid?

It depends on the concentration of ethanol in the solution. The flashpoint of ethanol will increase as the concentration go down. 

In other words, the more concentrated an ethanol solution, the more flammable it is, and vice versa. 

Pure ethanol is a class 1 flammable liquid with a flashpoint of 55°F and a boiling point of 78.2°C (172.76oF.)

On the other hand, 10% and 5% ethanol have higher flashpoints. The flashpoint of 10% ethanol solution is 120oF (49oC), and 5% ethanol is 144oF (62oC). 

Therefore, they are classified as class 2 flammable liquids. Class 2 flammable liquids are less flammable than those in Class 1 and, thus, slightly safer.

What is ethanol?

One of Ethanol’s most well-known characteristics is its distinct smell and flavor of vinous vinegar. 

A hydroxy group replaces one of the hydrogens in ethane to form ethanol, the primary alcohol. It has a flashpoint of 55°F and a density of 6.5 lb/gallon. In terms of density, the ethanol fumes are denser than the surrounding air.

Among its many industrial uses, ethanol is a solvent, a building block in producing other organic compounds, and even an ingredient in gasoline (to form gasohol). 

Many alcoholic beverages, such as gin, vodka, and beer, include ethanol as an intoxicating element.

How is ethanol produced?

Two primary methods are employed to make ethanol: carbohydrate fermentation (the method used to make alcoholic drinks) and ethylene hydration. 

Carbohydrates are converted to ethanol during fermentation by the growth of yeast cells. Sugar plants like sugarcane and beets, as well as grains like corn, are the primary resources for manufacturing industrial alcohol (maize). 

Fractional distillation is required to concentrate ethanol that has been acquired either via fermentation or synthesis. 

Ethanol concentrations of 95.6 wt.% can only be obtained via direct distillation. Anhydrous or pure alcohol is produced when the constant-boiling-point combination is dehydrated. 

It is common for industrial ethanol to be denatured with kerosene, benzene, or methanol, making it unsuitable for human consumption.

The structure of alcohol is:

What is the flashpoint of ethanol?

The flashpoint of ethanol depends on the concentration. Here is the list of ethanol-water solutions from 5%-96% concentration:

vol %flashpoint

What is flammable liquid?

OSHA specifies a flammable liquid as any liquid with a flashpoint of 93°C (199.4°F) or lower.

According to the National Fire Protection Association (NFPA), flammable liquids have a flashpoint below 37.8oC (100oF). They are categorized as Class 1, 1A, 1B, and 1C, depending on other factors that increase fire danger. 

Combustible liquids are classified as Class 2 and 3, then divided into Class 3A and 3B based on specific fire risk parameters.

Liquids classified as Class 3B have flashpoints equal to or above 100oF (37.8oC).

Regarding fire safety, Class 1 liquids are the most dangerous, while Class 3B is the safest.

What does it mean by class 1 flammable liquid?

Class 1 flammable liquids are those with flashpoints lower than Flashpoints & boiling points less than 37.8°C (100°F). It is the most hazardous class among all classifications of flammable liquids. Class 1 is further divided into Class 1A, 1B, and 1C based on other factors affecting the fire risk.

What is the difference between Class 1 and Class 2 flammable liquid?

According to NFPA, liquids in Class 1 are categorized as flammable, while class 2 is combustible. The flashpoints of class 1 flammable liquids have flashpoints below 37.8°C (100°F), while Class 2 between 100°F – 140 °F (37.8°C – 60 °C).

In contrast to Class 1 liquids, which may ignite at room temperature, Class 2 liquids require heat to burn.

What are the classifications of flammable liquid according to NFPA?

Flashpoints and boiling points below 37.8°C (100°F) are considered Class IA liquids. As a result, Class IA flammable liquids are also classified as flammable. Ethylene oxide, methyl chloride, and pentane are some standard Class IA liquids to find in a home or workplace.

Flashpoints lower than 22.8°C (73°F) and boiling temperatures higher than 37.8°C (100°F) are considered to be Class IB liquids. A few examples of common Class IB liquids are isopropyl alcohol, acetone, benzene, ethyl alcohol, and gasoline.

More specifically, the flashpoint of Class IC liquids is between 73 and 100 degrees Fahrenheit (22 and 37 degrees Celsius). Turpentine and butyl alcohol are two of the most often used Class IC liquid solvents.

Liquids with a flashpoint more than or equal to 100 °F (37.8 °C) but less than 140 °F (60 °C) are classified as Class II combustibles. Stoddard solvent, pine tar, diesel fuel, and camphor oil are examples of Class II liquids.

For Class 3A flammable liquids, the flashpoint must be at least 140 degrees Fahrenheit (60 degrees Celsius). Several examples of Class 3A liquids include fuel oil, formic acid, and creosote oil.

Liquids classified as Class 3B are flammable liquids with a flashpoint of 200 °F or above. Olive oil, fish oil, coconut oil, and castor oil are typical Class 3B liquids.

What is the flammability classification system based on?

According to the NFPA flammability classification system, the lowest temperature where the adequate vapor is released off the liquid to produce an ignitable combination with air is a primary factor in assigning a flammability rating.

The NFPA classification depends on adjusted flashpoints at sea level. Because of the decreased air pressure at higher altitudes, the liquid’s exact flashpoint would be lower. When handling or storing such substances, this will impact the danger of fire.

NFPA 30 and other NFPA codes and standards use these categories to determine fire safety codes for storing and handling flammable and combustible liquids.

Frequently Asked Questions (FAQs): Is ethanol a class 1 flammable liquid?

How to handle ethanol safely?

  • You should always wash your hands after using ethanol.
  • Be sure to use this product in a well-ventilated environment only.
  • When moving material, make sure the containers are well-grounded and well-bonded.
  • Use only spark- and explosion-proof instruments.
  • Eye, skin, and clothing contact should be avoided.
  • Empty containers could be harmful because they contain product remains (liquid or vapor).
  • Maintain a tight seal on the container.
  • Avoid being near sources of heat or fire.
  • Take care not to eat or inhale.
  • You should not use any pressurization, cutting, welding, brazing, or soldering process on an empty container.

How to store ethanol safely? 

  • Avoid being near sources of heat, fire, or any ignition sources.
  • Ensure that the container is firmly sealed.
  • Refrain from coming into contact with anything capable of oxidizing.
  • A well-ventilated, cold, and dry place is ideal for storing.
  • Nitric acid, chromic acid, peroxides, and perchlorates should not be stored alongside ethanol.


In this blog post, we have answered the question, “is ethanol a class 1 flammable liquid?”. We have also discussed what ethanol is, the flashpoints of ethanol in various concentrations, and classifications of flammable liquid according to NFPA and OSHA.

If you have more questions about ethanol and flammability, do not hesitate to comment down below.


National Center for Biotechnology Information (2022). PubChem Compound Summary for CID 702, Ethanol. Retrieved June 23, 2022, from

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