Flammable Vs. Combustible Liquids – Properties & Hazards
Atom Alloys
May 23, 2021
3 Mins Read Time

In UAE, a spate of car fires caused due to high temperatures was witnessed in the Hadath area of Umm Al Quwain, in August 2017. Analyzing the situation, Sergej Korogodin, General Manager of ZNZ Garage said, “The first and most major cause is a fuel leak, fuel leak from fuel pump, fuel lines or tank. Fuel and especially fuel fumes are highly flammable and a cigarette butt or even high temperature can start a fire.”

Now, be it a car fire or an industrial fire, it becomes vital to understand the underlying principles of combustion to work on fire safety processes. Fire is a manifestation of uncontrolled combustion. The ease with which a fire can be initiated, the rate with which the fire can aggravate (flame spread), and the power that can be generated (rate of heat release), can be quantified and predicted by understanding the properties of the combustible and flammable materials that are present in almost every workplace. In the US, flammable and combustible liquids are fundamentally regulated at the federal level by the Occupational Safety and Health Administration (OSHA) under 29 CFR 1910.106 (general industry) and 29 CFR 1926.152 (construction). The National Fire Protection Association (NFPA) sets agreeable codes and standards for flammable and combustible liquids under NFPA 30: Flammable and Combustible Liquids, which generally complies with OSHA and many state and local regulations.

Understanding Flashpoints of Flammable and Combustible materials

Flashpoint is the lowest temperature at which vapor generates from a liquid, which when combined with air ignites near the surface of the liquid on exposure to an ignition source. This temperature varies from material to material and it is this flashpoint that determines the threshold of each material and differentiates flammables from combustibles.

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A material is considered to be flammable if its flashpoint is any value of temperature below 100.04 ºF, while it is termed as a combustible material if it has a flashpoint higher than 100.04 ºF and lower than 199.94 ºF. Both these materials would produce vapors when exposed to a temperature equal to or above its flashpoint. It is more likely for the flammable materials to be prone to ignition as it has a lower flashpoint and they would be susceptible to forming vapors in normal work environments. Whereas in the case of combustibles, these materials will not form vapors in normal work environments, as the temperature of most workplaces will not be above its lowest flashpoint of 100.04 ºF. It is imperative to set disaster prevention based on the external surrounding temperature as it affects the formation of vapors. For instance, the climatic conditions in India may result in liquids having lower flashpoints, in contrast to the flashpoint values of liquids when used in Europe and the USA.

Risks of Flammable and Combustible Liquids

Fire takes different forms depending on the circumstances and it becomes important to understand the type of fire to determine the origin and cause of the fire. Here too the flammability and combustibility factors have significance.

Diffusion Flames: In combustion, diffusion flames are flames in which the oxidizer and fuel are separated before burning. A candle burning is a classic example of diffusion flames. Diffusion flames are also called non-premixed flames.

Surface Fires: These fires occur at the surface and are relatively the easiest fire to be put out. They occur no taller than an average human being and create the least amount of destruction as they burn only surface litter and duff. They are fueled by low-lying vegetation on the floor that becomes dry enough to burn.

Explosion: Explosive combustion occurs at a rapid pace. A sudden reaction that takes place on the ignition of certain substances to produce heat, light and sound is called an explosion. Explosions could occur as a result of natural, chemical, mechanical or nuclear causes. Some of the notable explosions to quote are the ones that shook Beirut, Herat, Houston and Madrid in the last one year alone.

While fire protection & mitigation measures can only address diffusion fires and surface fires, it requires an unabating explosion prevention system to address and prevent fuel explosions. Today, we have revolutionized solutions to prevent such hazards like explosions while dealing with highly flammable liquid and gaseous hydrocarbons. Are you thinking of taking your first step towards explosion prevention? Reach out to our passionate team of experts at ATOM, who strives towards providing extraordinary prevention solutions against explosions, changing practices and saving lives.

Reference: – Combustibility and Flammability, Explosion – Safety Measures - OSHA & NFPA specifications



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