Is formic acid flammable?

In this blog post, we will answer the question, “Is formic acid flammable?”. We will also discuss what formic acid is, the NFPA fire rating for formic acid, the reactivity of formic acid, and how to extinguish fire caused by formic acid. 

Moreover, this blog also covers how to store formic acid safely and what should you do in an accident when handling formic acid.

Is formic acid flammable?

Yes. formic acid is flammable. It has a flash point of 156°F (68.9oC). This implies that the explosive vapor of formic acid or air mixes can form at 156°F (68.9°C).

This flash point is low, making formic acid categorized as a flammable liquid according to OSHA.

What is formic acid?

Formic acid (HCO2H), or methanoic acid, is the simplest carboxylic acid utilized in the leather and textile industry. To honor the Latin word for “ant,” formic acid was called after the ants who produced it. It is made when sulfuric acid reacts with sodium formate. 

Formic acid in its purest form is a colorless, fuming liquid with a pungent odor that irritates and blisters the mucous membranes. 

8.4°C (47.1°F) is the freezing point, and 100.7°C (213.3°F) is the boiling point.

The structure of formic acid is:

In the presence of a catalyst, formic acid can also be synthesized from carbon monoxide and alcohol such as methanol (methyl alcohol). 

In contrast to the usual carboxylic acids, which can create an anhydride, formic acid has a high acid strength, low anhydride formation, and high reduction reactivity, all of which are attributed to the CHO group, which gives it some of the characteristics of an aldehyde. 

Formic acid methyl and ethyl esters are mass-produced.

Formic acid dehydrates carbon monoxide when exposed to concentrated sulfuric acid.

What is the NFPA fire rating for formic acid?

Formic acid has a flammability value of 2. This means igniting formic acid requires either a moderate heat source or a reasonably high ambient temperature. 

Under normal conditions, formic acid would not cause any danger, but heating could release enough vapor to produce hazardous byproducts with air.

What is the reactivity of formic acid?

  • The exotherm reaction occurs with all bases, both organic and inorganic.
  • Hydrogen and a metal salt are formed when hydrogen reacts with active metals.
  • It produces gaseous hydrogen cyanide after reacting with cyanide salts.
  • Gaseous flammable or poisonous products can be formed when reacting with diazo compounds, sulfurides, nitrides, mercaptans, isocyanates, and dithiocarbamates.
  • Reacts with dithionites, thiosulfates (to make H2S and SO3), nitrites, and sulfites to produce heat and gases that can be toxic or flammable.
  • Carbon dioxide and heat are produced due to the reaction with carbonates and bicarbonates.
  • Potent oxidizing and reducing agents can oxidize and reduce formic acid.
  • Heat is produced as a result of these processes. Polymerization processes or other chemical reactions may be catalyzed by formic acid.

How to extinguish fire caused by formic acid?

Use dry chemical, carbon dioxide, or water spray to extinguish a small fire. 

Large fires should be tackled using dry chemical, carbon dioxide, alcohol-resistant foam, or water spray. If it is safe to do so, remove containers from the fire area. Do not scatter fire-control water; keep it in a dike for later use. 

For fuel tank, trailer load, or vehicle, use unmanned monitor nozzles, hose holders, or fight fires from a distance as far away as possible. Containers should be kept dry at all times. 

Until the fire is completely extinguished, flood the containers with water to keep them cool. 

If there is a soaring noise from venting protection equipment or a change in the color of the tank, immediately exit. Tanks that are on fire must be avoided at all costs.

How to store formic acid safely?

  • It must be kept from highly reactive substances, such as oxidizing agents, strong acids, bases, and foodstuffs.
  • Avoid heat, sparks, & open flames at all costs.
  • Protect yourself from being hurt in any way.
  • Well-ventilated, dry, and cool place is best to keep formic acid. Outdoor storage is advisable.
  • Close the lid securely.
  • Don’t smoke, drink or eat in places where formic acid is used or stored.
  • Open the container outdoor and upwind if possible, particularly in hot weather.

What should you do if you get formic acid splashed into your eyes?

To begin, look for your contact lenses and remove them. For 20 to 30 minutes, flush your eyes with water or standard saline solution while dialing 911 or your local poison control center. 

Avoid applying ointments or oils to your eyes unless specifically instructed by a doctor. Even if you don’t notice any injury (such as redness or irritation) after flushing your eyes, you should go to the hospital immediately.

What should you do if formic acid gets in contact with your skin? 

As soon as possible, thoroughly wet the affected area and remove all contaminated clothing. 

Use mild soap and warm water to cleanse the affected areas of the skin deeply. Even if you don’t notice any injury (e.g., irritation, redness), call a hospital or poison control center. 

After washing the affected area, directly go to the hospital for treatment. 

What should you do if you accidentally inhale formic acid vapor? 

Exit the contaminated area as quickly as possible and take deep breaths of fresh air as you do. 

It is best to consult a doctor immediately if you experience any symptoms (such as coughing, wheezing or a burning sensation in your mouth, throat, or chest).

Rescuers entering an unfamiliar environment should be equipped with proper respiratory protection. A degree of safety equal to or greater than that provided by Protective Clothing (PC) should be used whenever possible; if SCBA is not readily accessible, use a higher level of protection. 

What should you do if you swallow formic acid by accident?

DO NOT VOMIT. The mouth, throat, and esophagus can be damaged by corrosive chemicals, which can also be aspirated into the lungs during vomiting, resulting in even more medical issues. 

Take some sips of water to dilute the acid, then call a hospital or poison control center as soon as possible. Go to the hospital right away. 

You should not give anything by mouth to someone who has accidentally swallowed formic acid and is now gasping for air or unconscious. Instead, make sure their airway is open. 

Then, place the victim on their side with the head lower than the body to ensure that they have an open airway. VOMITING SHOULD NOT BE CAUSED IN ANY WAY. The victim should be taken to the hospital as soon as possible.


In this blog post, we have answered the question, “Is formic acid flammable?”. We have also discussed what formic acid is, the NFPA fire rating for formic acid, the reactivity of formic acid, and how to extinguish fire caused by formic acid. 

Moreover, tips on how to store formic acid safely and what should you do in an accident when handling formic acid are covered in this blog.

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

Frequently Asked Questions (FAQs): Is formic acid flammable?

Why is formic acid associated with ants?

Stinging nettles contain formic acid, which causes a burning sensation when they come into contact with the skin. 

Many insects, such as bees and ants, have stings and bites containing it as a chemical defense. 

During the strike, the formic acid in the ant’s toxin gland is released into the air in jets, which may sting an assailant from up to one meter away. Attackers retreat or are killed because formic acid has a pH of 2-3.


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