Is Fuel Oil Flammable? 

This article will answer the question, “is fuel oil flammable”? It also covers several topics about fuel oil types, their properties, and the precautions for safely handling fuel oil.

Is Fuel Oil Flammable?

Fuel oil is flammable due to its low flash point. Fuel oil is used as an energy-producing material, for example, for vehicles, heat generators, and others.

What Is the Definition of Fuel Oil?

Refining crude oil results in the production of a fuel known as fuel oil. The processing of that oil follows the extraction of crude oil from the depths of the earth in a refinery, which is the first step in producing oil products, which can include gasoline. 

One of the commodities that can be extracted from natural gas and oil resources is fuel. Petroleum and natural gas are examples of strategic nonrenewable natural resources. 

Oil and natural gas are essential commodities that determine how many people can support themselves financially. Petroleum and natural gas play a significant part in the functioning of an economy. 

The formation of petroleum occurs due to a natural process involving the accumulation of hydrocarbons in a molten or solid state under high pressure and high-temperature conditions. 

This includes bitumen, mineral wax, or ozokerite, all of which are products of the mining process. Asphalt is also included. 

However, it does not include coal or any other reserves of hydrocarbons in a solid form obtained by activities unrelated to the oil and gas industry. 

A natural process produces natural gas in the form of hydrocarbons when those hydrocarbons are subjected to atmospheric pressure and temperature in the form of a gas phase.

What Are the Types of Fuel Oil?

Distillate and residual fuel oils are the two most common types of fuel oils. During the distillation process, the distillate fuel oil is vaporized and condensed, resulting in a specific boiling range and the absence of high-boiling ingredients. 

The composition and impurities of residual fuel oils are more complex than those of distillate fuel oils because they comprise remnants from the crude distillation and thermal cracking processes.

Based on its characteristics and utilization, fuel oil is divided into these categories:

Marine Fuel Oil

Fuel oil is generated from black residue. Compared to diesel oil, MFO has a higher viscosity. Large corporations and steam power plants frequently use this fuel oil type for direct combustion, although it can also be used in a wide range of other industries.

High-speed Diesel

Many motorized vehicles and industrial machines run on diesel oil as their primary fuel. In HSD (High-Speed Diesel) engines, mechanical pumps and electronic injection are used.


In terms of fuel oil for automobiles, gasoline is the most commonly used variety and is widely available. Gasoline is the preferred fuel oil for ignition-operated combustion engines. The health of your machine can be adversely affected by the fuel you use.


This fuel oil is well-known to homeowners and small-business owners alike. Kerosene or kerosene is an essential component of crude oil with a boiling point between 150 and 300 degrees Celsius and is colorless.

Aviation Gasoline

Avgas, often known as aviation gasoline, is a refined petroleum fraction-based fuel oil. This fuel oil can only be used in aircraft with an internal combustion engine, such as a piston engine with an ignition system.

Aviation Turbine

Avtur is a petroleum fraction-based fuel oil, similar to Avgas, that is frequently referred to as “Avtur.” Avtur is used in aircraft fuel oil with a turbine engine or external combustion, while ordinary aviation fuel oil is not.

Marine Diesel Oil

Black oil, which is liquid at low temperatures, is refined into diesel oil (MDF). Because this diesel oil has a low sulfur content, Medium Speed Diesel Engines can accept it in the industrial sector.


Biodiesel is made from various oils, including those derived from plants and animals. Mono-alkyl esters of long-chain fatty acids are the building blocks of biodiesel.

What Are the Properties of Fuel Oil?

Oils used in motor vehicles contain modest concentrations of sulfur, nitrogen, and oxygen components in complex and variable mixes of aliphatic (alkanes, alkenes, and cycloalkanes) and aromatic hydrocarbons. 

Various factors, such as the refinery where the oil was refined, the inclusion of additives or modifiers, and more, influence the exact chemical makeup of different types of fuel oils. 

The following are the primary properties of fuel oil as a fuel that must be met for it to burn correctly and supply power to a vehicle’s engine:

Speed of Evaporation

A fuel oil’s evaporation speed is determined by whether or not it is easy to evaporate under particular conditions, such as sufficient oxygen content around the fuel oil and an adequate temperature. The faster fuel oil molecules evaporate at a higher temperature.

Tendency to Detonate

Denotation is the combustion process in the engine that causes heat as a result of combustion, causing the fuel oil mixture that has not been exposed to sparks from the spark plug to experience discharge. A solid inclination to detonate can harm the motor.

Octane Number

An octane number is used to represent the likelihood that fuel oil may explode, and the number in fuel oil is an integer that includes several percent of iso-octane and heptane. 

The heptane number is reduced to zero, and the octane is given the value of 100. Eighty-six percent iso-octane and 24 percent heptane are found in fuel oil with an octane value of 86. A fuel oil’s detonation risk decreases with increasing octane rating.

Sulfur Factor

Damage to engine components can occur when fuel oil has a high sulfur level. Sulfur concentration is limited to 2%, and it is strongly advised to be lower.

Level of Resin

Fuel oil can damage engine components like valves, drains, and pistons due to resin’s stickiness. Fuel octane numbers can be lowered when resin levels are high in a storage tank, which can harm the engine. 

As a result, fuel oil’s maximum acceptable resin content is 10 mg per 100 cm3 the more prolonged the storage procedure lasts.

Freezing Point

It is the point at which something becomes wholly frozen. The freezing point of fuel oil is the temperature at which it begins to freeze. This process can occur if aromatics in fuel oil are present, and these aromatics will freeze at specific temperatures. 

An obstruction in the fuel oil line can arise if the freezing process occurs. The freezing point of fuel oil used in automobile engines must be approximate -50°C in locations with cold weather.

Point of Dew

The dew point of fuel oil is the temperature at which fuel oil begins to condense. It is wasteful to utilize fuel oil with a high dew point because any fuel oil droplets that remain on the suction line can make their way inside the cylinder. 

Due to inhomogeneous circumstances in the cylinder, inefficient combustion might occur. Motor vehicles’ dew points are limited to 140°C.

Flash Point

The point at which everything changes.

Airborne fuel oil fumes can catch fire when heated to certain temperature or lower by applying a spark to the flash point.

Relative Density

The API (American Petroleum Institute) standard scale is commonly used to express the specific gravity of fuel oil, with a standard of 67.8°API or 0.71-0.77 g/cm3.

What Are the Precautions for the Safe Handling of Fuel Oil?

  • Operators must be adequately educated, trained, and informed.
  • There should be enough ventilation.
  • Proper personal protective equipment can help you avoid injury (PPE).
  • Do not touch any ignition source such as heat, hot surfaces, sparks, or open flames.
  • Smoking is forbidden near the fuel oil source.
  • Remove out the reach of children and animals, as well as pets.
  • Avoid exposing the store to direct sunlight.
  • Temperature and ventilation are essential for keeping the container sealed tightly.
  • Avoid contact with your skin, eyes, and clothing.
  • Inhalation of vapor or aerosol is not recommended.


Fuel oil classes are distinguished by their properties. Some storage management can keep fuel oil from igniting. 

Frequently Asked Question (FAQs): Is Fuel Oil Flammable?

Is there a difference between oil and petrol?

Petroleum is most commonly used to refer to crude oil that has been produced from the earth, although the phrase “oil” can apply to a wide variety of oils, including those used for cooking, lubrication, engines, etc. However, this does not cover gasoline.

When does fuel oil start to burn?

The flash point, also known as the temperature at which the oil will catch fire on a burner, is 140 degrees Fahrenheit. This is also the temperature at which it will begin to evaporate. 


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