This video will cover 5 flammability tests. When it’s over you’ll understand what the flammability tests are, why you need them, and how they relate to each other. The first thing we must understand is the FIRE TRIANGLE. Combustion cannot occur unless all three aspects of the triangle are present. Those three aspects are: Fuel, or any reducing material capable of being oxidized; Oxidant, or an oxidizing material capable of being reduced; And Ignition Source, an external source of energy. Most of these tests are dependent on these factors: Geometry, Strength of Ignition Source, Direction of Flame Propagation, Temperature, Pressure, Levels of Interts/Oxidizers, Mixture Composition, and Vessel Size. It is important to test at conditions that are as close as possible to actual process conditions for the most applicable results. As we look at this graph:
We see how four of the five tests are related to each other as functions of temperature vs. fuel concentration. The remaining test will be discussed later in this video.
Vapor Pressure - Vapor pressure is the force applied by a vapor in equilibrium with its solid/liquid phase at a set temperature or range in a closed system. As temperature and vapor pressure increase, if the material is flammable, eventually there will be enough flammable vapors to create a potential fire hazard. Remember, liquids do not ignite, it’s the vapors of liquids that ignite. The threshold where a material becomes a flammable hazard is the Flash Point.
The Flash Point is the lowest temperature where the necessary vapor concentration has been reached that allows for the propagation of a flame when an ignition source is applied.
Flammability Limits - You’ve got your LFL and your UFL. The flammable region begins and ends between the two. In order to conduct an LFL, the chemical must have a flash point, and the temperature of the testing environment must be above it. Knowing these limits is valuable, because operating close to, but outside of them, maintains safety while also potentially keeping product yields high. Chapter 8 of NFPA 69 advises the permissible safety margin necessary when operating near the flammability limits. If operating outside of the flammable region is not possible, the oxidizer can be reduced to create an inert environment.
Limiting Oxidant Concentration - The limiting oxidant concentration is the minimum amount of an oxidant needed to support an ignition. Knowing the LOC helps determine proper inerting and purging procedures to maintain safety while remaining inside of the flammable region. Chapter 7 of NFPA 69 advises the permissible safety margin necessary when operating below the LOC.
Autoignition Temperature or (AIT) – Is the lowest temperature at which a gas or vapor will spontaneously ignite with heat acting as the ignition source. Knowing the AIT is important if chemicals are being handled or processed under elevated temperature conditions.
So there you have it! Now you understand what the flammability tests are, why you need them, and how they relate to each other. For more information, please contact email@example.com Thank you for watching!