Our safety culture has changed significantly over the years with regards to dust hazards and dust collection systems. This can be attributed to tragic events such as explosions and fires that have prompted education and a better understanding of the hazards posed by combustible dust. This has led to changes to regulatory safety codes, a questioning attitude by employees, and closer examination and enforcement by fire prevention officers or other code enforcement authorities.
Dust collection systems are essentially a safety system as they should remove the fine volatile dust from operations and help prevent hazardous dust accumulations in buildings. However; even though they provide a safety function, the process of collecting combustible dust is hazardous and protection measures are needed to protect workers and the operations.
When dealing with dust collection systems, the National Fire Code of Canada and other provincial Fire Codes have requirements for how to protect your dust collector. The National and Provincial Fire Codes may have different protection. The National Fire Code of Canada and other provincial Fire Codes also specify a vent area of 0.1 m2 for each cubic meter of dust collector enclosure volume. This does not align with the standard on explosion protection by deflagration venting (NFPA 68) which these codes also reference. Venting will protect the equipment but will not necessarily prevent deflagrations from spreading back into the building or to connected equipment. As you can see, determining the protection required for dust collectors can be difficult, and may not be adequate, if you only apply local codes.
At PLC Fire Safety Engineering, we focus not only on the local fire code requirements but also on understanding the processes and materials being handled when examining dust collection systems. Not all materials are the same, and not all processes handling or creating dust are equally hazardous. Some hazardous processes may require spark detection and extinguishing systems, sprinkler protection and explosion protection. To know what protection is required for your dust collector, many factors should be considered. Below is a list of some of the common factors:
- Dust collector location (indoors or outdoors);
- Material(s) being handled (e.g. wood dust, starch, coal dust, titanium dust);
- Process hazards and possible ignition sources;
- The dust collection unit design in terms of strength and volume;
- Connected equipment and if exhaust air is returned to the building; and
- Exposure potential to building personnel or the public when using venting.
The National Fire Protection Association (NFPA) have many standards that provide guidance on assessing combustible dust hazards, detailing protection requirements based on the type of facility and hazardous operations (e.g. woodworking, agricultural, metal dust, etc.) and requirements for designing effective explosion protection systems. All the factors listed above, and more, are addressed in these NFPA standards. Compliance with the appropriate NFPA standards for protecting your dust collection systems will not only meet the intent of local Fire Codes, it will ensure that your building occupants are safe, and your process is protected from long term interruptions and significant financial losses.
Please contact us at PLC Fire Safety Engineering if you have any questions or concerns regarding your dust collection systems.