Difference between Flammable and Inflammable

We have often heard terms like flammable, inflammable, combustion, etc., and have even studied it in our chemistry lectures. But do we really understand what these terms mean? Students are often confused between these terms. Flammable and inflammable might seem to be the same, but they have some basic differences.

Students might get confused between these two terms because both the terms are associated with flame. So, let us first see the fundamental differences between them.

These are the basic differences between flammable and inflammable substances. Well, some people might think that both words mean the same because they have flame word in them. It might be true because both the terms mean that they can catch fire. The difference lies that flammable substances catch fire easily, and inflammable substances are harder to ignite, i.e., they do not catch fire easily.

Well, it interesting to note that in the 1920s, the National Fire Protection Association urged people to use the word 'flammable' instead of 'inflammable.' The main reason for changing the terms was that people might get confused with the term inflammable. They might think that inflammable might mean the things that do not catch fire. That is why the term inflammable was changed to flammable so that the people might not get confused between them.

The substances that do not catch fire are called non-flammable substances. For instance, oxygen is a non-flammable substance. It is an oxidizer and does not catch fire. But oxygen can give rise to fire. The fire can be increased with the help of oxygen.

The word inflammable has been derived from the Latin word 'inflammare,' wherein 'flammare' means 'to catch fire' and the prefix 'in' means to 'cause to.' The term inflammable was found by a Latin scholar in the year 1813.

But when it comes to the difference between flammable and inflammable substances, the only difference between them is how readily the substances catch fire. Out of these two terms, the term flammable is more appropriate and is widely used. On the other hand, inflammable is an older term than flammable because it was coined first. People were advised to use the term flammable to avoid confusion.

Well, it is interesting to note that flammable substances are present in solid, liquid, and gaseous states. To determine the flammability of a particular substance, it is important to see some factors on which the flammability depends. Let us look at the factors below:

1. Flash Point: Flash Point means that the flammable substance can evaporate and ignite at low temperatures. The flash point is defined as the temperature at which the flammable vapors are released from the substances to ignite them. For instance, petrol can ignite at a temperature of -43 degrees, and kerosene has a flash point of 37 degrees.
2. Auto-Ignition: The temperature at which a flammable substance burns and continues to burn is called the auto-ignition temperature. Any flammable substance burns if it is subjected to extensive heat.
3. Flammable Limit: When the vapors of flammable substances are in the air, and they come in contact with the liquids, they tend to ignite. The vapors are present at a certain level in the air. These levels are divided into two sections, i.e., Lower Flammability Limit (LFL) and Upper Flammable Limit (UPL). As the name suggests, the lower flammability limit is a situation where in the flammable substances ignite with the lowest concentration of flammable vapors. On the other hand, the upper flammability limit is a situation wherein the flammable substances require the highest concentration of vapors to ignite.

So, these are the important factors that are required to determine the flammability of a substance. Flammable and inflammable substances mean the same thing. They only differ in one aspect, i.e., the rate at which these substances burn. Flammable substances burn at a faster rate, while inflammable substances ignite gradually. This is the only basic difference between flammable and inflammable substances. Thus, flammable and non-flammable substances are different yet similar to each other.