The Difference Between Flashpoint and Ignition Temperature

by HSE DOCUMENTS on January 05, 2021 in EHS Guidelines

There are numerous techniques and conditions used for measuring the flammability and combustibility of chemical, liquids or substance. Here we are going to discuss following 2-Two of these terms:

A. flash point

B. ignition temperature.

Although they share similar properties but, they are very different terms.

Now we discuss each of the term in detail definition.

1. Flash Point

The flash point is the lowest temperature at which a substance, chemical, liquids or substance vaporizes into a gas, which can be flare up with an external source of the fire. There are two main methods of measuring a flashpoint such as open cup and closed up.

Open Cup Flashpoint Testing (OCFT) happens when the chemical, liquids or substance is stored or kept into a vessel which is exposed to the external atmosphere. Its temperature is then steadily raised, and an ignition source is passed over the top of it at intervals. Once the chemical, liquids or substance “flashes” or becomes ignited, it has reached its flashpoint.

Closed Cup Flashpoint Testing (CCFT) is carried out inside a sealed vessel and the source of ignition is inducted into the vessel. As a result, the chemical, liquids or substance is not exposed to the elements external of the vessel, which can have an interrupting effect on the results of the CCFT test. This, in reply, also undergo to lower flashpoints, because the heat is trapped inside. Due to its lower capacity, the flashpoint is also secure for comprehensive use, and as such is more frequently accepted.

2. Ignition Temperature

Contrary to flashpoints, the ignition temperature does not require an ignition source. In other words, the ignition temperature is the lowest temperature at which a volatile or unstable chemical, material or substance will be vaporized into a gas which ignites without any help of any external flame or ignition source. As a result, the ignition temperature is of course higher than the flashpoint.

Generally, ignition temperatures are measured by placing the chemical, liquids or substance in a half-liter vessel and inside a temperature-controlled oven. The current standard procedures for such tests are outlined in Standard Test Method for Autoignition Temperature of Chemicals (ASTM E659).