In 2018, several of my clients have identified combustible dust concerns. The first step is a review of the Safety Data Sheet (SDS) of the material in question. With OSHA’s adoption of the Globally Harmonized System (GHS), OSHA amended the definition of “hazardous chemical” to include combustible dust. Manufacturers and importers are required to classify their chemicals’ combustible dust hazards in the form they are shipped as well as hazards that arise under normal conditions of use and foreseeable emergencies. Unfortunately, the SDS is not always a good source of information with respect to identifying whether or not a material is a combustible dust hazard.
If you have a chemical you suspect may be a combustible dust, the first step is to review the SDS to determine if it has been identified as a potential combustible dust hazard. If the SDS does not address this issue or you require additional information, contact the supplier/manufacturer.
If you are still not sure whether your material poses a combustible dust hazard or the degree of hazard, it may be time to consider having a laboratory perform combustible dust testing. There are several accredited laboratories that perform this testing. Although testing protocol may vary depending upon the material, many laboratories recommend staggered testing dependent upon initial testing results:
Go/No-Go: This is a first-pass test to simply determine if the chemical is combustible. Some chemicals are “no-go” and do not require additional testing. If the material is a “Go,” additional testing is usually recommended to ascertain the degree of combustibility.
Second Round: If the initial testing was a “go,” the second round of testing is normally performed to further determine the chemicals level of combustibility. Depending upon the material, it is typical to perform the following tests during the second round: Explosion Severity (Kst); Minimum Ignition Energy (MIE); Minimum Ignition Temperature (MIT); and Layer Ignition Temperature (LIT). Depending upon round two results, the chemical may no longer considered an explosion hazard, or additional testing may be required.
Third Round: The second round has further classified the chemical as combustible but perhaps the level of hazard is still not fully quantified. Typically, the third round of testing only requires one additional test be performed. For example, a laboratory advised a client they only needed to test the chemicals Minimum Explosive Concentration (MEC) during the third round of testing. Once these results are obtained, the degree of combustibility may now be fully understood.
Why do laboratories often perform combustible dust testing in this fashion? The testing is not cheap and many times if you are testing several chemicals you may have several be a “no-go” and you can eliminate spending additional funds on further testing. Also, you need to clearly determine the degree of the combustible dust hazard prior to making expensive equipment upgrades.
Jon