How Well Do You Know Your Dust? (continued)

Specialized Testing

The explosibility and bench tests described above will be sufficient in the great majority of cases. Sometimes, with a highly unusual or trouble-prone application, additional testing might be dictated.

Explosion test labs have the capability to perform a variety of advanced tests using both small- and large-scale explosion test vessels. A reputable lab will be able to make recommendations on further testing needed to analyze your combustible dust problem.

Similarly, after bench testing is completed, you might need further information to troubleshoot a serious collector problem or to predict the behavior of an unusual or difficult dust. In these situations, full-scale dust testing using one or more dust collectors may be considered. Full-scale testing apparatus is available from a handful of labs and may be used for real-time or accelerated testing that simulates actual operating conditions.

A Note on Sampling Procedures  

Proper collection of the dust sample is important to make sure that it represents the state in which the filter will collect it. Begin by reviewing the dust's Material Safety Data Sheet to ensure that you take precautions against any hazards associated with the dust.

Every dust is different. The only way for plant personnel to know their dus is to commission laboratory testing.

If you have an existing dust collector, a dirty bag or cartridge is an ideal sample. Otherwise, take care to collect a sample that represents the dust to be captured by the collector. For example, dust swept from the floor is not representative, because it will contain impurities and larger particles with enough mass to have fallen to the floor. Dust from a hopper is not recommended either, because the sample won't represent the true particle size distribution of the dust captured by the filters. Ask the lab for further guidelines on proper sample collection.

Explosibility testing typically requires a 1-lb. dust sample, while bench testing requires a separate 1-pt. sample. Always use airtight containers to preserve the moisture content of the samples. Full-scale testing will require much larger dust samples: Again, consult your test laboratory for details.

When you have finished collecting and testing your dust samples using these guidelines, you will know your dust much better. And knowing your dust is the key to making sure you have the best possible dust collection equipment for emission control, plant cleanliness, worker safety and comfort... and compliance.

***