Aqua Coat found this interesting article in the August 2020 edition of Woodworking Network written by Ben Dipzinski. As woodworkers, we have responsibility to manage our wood waste. New requirements in NFPA (National Fire Protection Association) 652 “Standard on the fundamentals of Combustible Dust” took effect September 1, 2020 and therefore require immediate attention.
As defined by NFPA “combustible dust” is “A combustible particulate solid that presents a fire or deflagration hazard when suspended in air or some other oxidizing medium over a range of concentration, regardless of particle size or shape.” Development of the NFPA 652 standard for combustible dust began in 2012. The main objective is to have manufacturers evaluate the potential of fire from combustible dust in the form of a “Dust Hazard Analysis.” As an owner, you are responsible for a DHA of your facility.
The key requirements for this NFPA 652 are:
- 1 requires that the “owners and operators of a facility…shall be responsible.”
- 1 requires hazard identification of materials.
- 1.1 requires a DHA for all existing and new process.
- 1.2 have a DHA on file by Sept. 7, 2020.
- 1.4 states the DHA must be updated every 5 years.
- 2.2 states that “the DHA must be performed or led by a qualified person.”
What does this really mean to us? You as a woodworker must evaluate your dust and determine which process is hazardous, provide a solution to eliminate or mitigate the hazard, and have a plan of action in case of an emergency. The goal is to eliminate the risk of injury or death from a combustible dust explosion. Key events needed to create this hazard are Fuel, Ignition, Oxygen, Confinement and Dispersion. As responsible woodworkers, our focus needs to be on the fuel. We need to keep the fuel (wood dust) off elevated horizontal surfaces and be diligent with housekeeping.
How to perform a DHA
Each manufacturing process needs to be evaluated-including work cells. Keep in mind that dust collection is also considered a process. Here is a checklist for woodworkers to evaluate their facilities.
- The DHA process starts with the evaluation of your dust, taking a sample of your material, and having it tested. Based on the Kst, combustible dust is ranked into one of four classes: ST0, ST1, ST2, ST3. You can expect to be categorized as ST1 (Kst<200). Most woodworkers have a Kst of 100-200, so yes you have combustible dust.
- Do you have an ignition source? Assume the answer is yes. Since no one knowingly allows open flames in the wood shop, assume that if there is a spark it will occur by accident, and you can’t plan when and how this happens.
- Do you have dust in sufficient quantity to be explosive? Typical woodworking dust collection ducting does not have enough concentration to produce an explosion. However, this can also depend on the type of wood waste; is it a chip or fine powder? Is there a high volume of wood dust generated at the process or machine? Particular areas of high-risk are the dust collector and transport line. There are many variances to dust collection systems, and some are higher risks than others.
- Is dispersion possible? Is there dust sitting on surfaces which can be disturbed and create a dispersion? This can happen when the dust collection is not sufficient, and operators use compressed air to clean surfaces. You have to identify these areas and create a plan to keep them clean.
Once you identify these problem areas, you need to develop internal processes to eliminate and monitor. This may include vacuuming versus blowing dust, increasing the cleaning of fugitive dust, evaluation of dust hoods, dust collection, or solutions for ceiling cleaning. For more information on this new requirement visit www.NFPA.org.