By Sara Peters, Fauske & Associates, LLC
It happens with some regularity – news of a fire or explosion in an industrial facility that causes considerable property damage or, even worse, worker casualties. It has been said before, but continues to remain true, even one incident of fires and explosions resulting from an employee in the building mixing chemicals, is one too many.
The all too frequent occurrence of fires and explosions in the process industries that use flammable materials is typically the result of a couple of factors, an explosive mixture being present in the vapor space, lack of knowledge of the properties of the chemical’s inherent safety implications or inadequate safety procedures. And, that in a nutshell, is why flammability testing is important.
In order to minimize the risk of fire or explosion, it is important to evaluate the flammability characteristics of the material to understand key characteristics such as the lower flammability limit, upper flammability limit, limiting oxygen concentration and deflagration index. Simply put, these are defined as:
- Lower Flammability limit (LFL) - the lowest concentration at which a mixture of flammable vapor or gas and air is flammable
- Upper Flammability Limit (UFL) - the highest concentration at which a mixture of flammable vapor or gas and air is flammable
- Limiting Oxygen Concentration (LOC) - the minimum concentration of oxygen required to produce a flammable event when mixed with a flammable vapor or gas in any concentration.
- Deflagration Index (KG) - the volume-normalized maximum rate of pressure rise for a flammable mixture
A variety of different flammability tests can be performed to allow for determination of these characteristics, and the understanding of these conditions is essential when implementing proper safety practices.
When conducting flammability testing, it is important that customers communicate what data is being sought so that testing can be properly designed in order to determine the necessary flammability property of a chemical mixture.
A good flammability testing regime will take into consideration the many different variables that affect the flammability of a specific chemical: oxidizing environment, temperature, pressure, ignition energy, size and geometry of the vessel, gas composition, etc. There are a variety of pressure vessels varying in size and geometry to use for flammability testing purposes dependent on the particular need. The choice (spherical, cylindrical, large, small, glass, steel, etc.) depends on the particular test design. A well defined ignition source is also necessary, as is a good data acquisition system for monitoring pressure and temperature.
Accounting for these variables can result in test data that is much more applicable to your specific process than information taken from literature. Experts are happy to have a discussion with you about your flammable hazard concerns and work with you on designing tests that get you the information you need. The goal is to provide you with specific data - not just data.
For more information regarding how flammability testing might be important to you, contact the flammability department at firstname.lastname@example.org. You can also subscribe to our quarterly Process Safety News below!