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Dust Hazard Assessment




Anyone working in a facility that handles dust (which is essentially every facility) is trying to get ready for the crackdown from OSHA and NFPA. While OSHA and NFPA are still trying to figure out the best way to implement new standards, what those standards will be and how to enforce the standards, NFPA and OSHA have come out with some temporary guidelines. OSHA put out the Dust National Emphasis Program and NFPA put out 654-TIA 06-1. In response to these, and the rumors that are flying about what is coming from both of these entities, the Company I work for has decided to proactively prepare for these changes. For the last couple of years I have been focusing on the existing dust collection equipment on site, and what will be required to make it safe (in accordance with the new/coming standards).
To assist me with evaluating these systems, I have developed a few spreadsheets to solve some of the more common questions.
First, I created a simple Dust Filter Volume Calculator. This workbook calculates the Dirty Air Volume for Drum and Cam-Vac style filters. The Drum Filter sheet lets you input how many filters there are, so you are not limited to just one. In addition, these sheets have an area to input the accumulation data from your inspection, along with the type of dust and the MEC (Minimum Explosible Concentration). Once you've input that data, it will calculate your dust concentration and the percent of the allowable LEL (Lower Explosive Limit) you had in the unit. This data will make it easy to print and retain for your records. This is valuable if you are relying on Explosion Prevention via Combustible Concentration Reduction (per NFPA 69, Chapter 8).
Next, In order to properly size your explosion vents (per NFPA 68, Chapter 8... or you could get Venting of Dusts and Hybrid Mixtures), you're going to need to know the Length to Diameter Ratio of your vessel. I've put together a workbook using the sample problems from NFPA 68, A.6.4.3. In addition to the simple L/D samples, I've extrapolated to get a couple of other common styles of Baghouses and Cyclones. This file is located at L/D Ratios for Cyclone and Baghouses and has Imperial inputs with Metric and Imperial outputs.
Finally, after NFPA 654 TIA 06-1 came out earlier this year, I created a workbook to figure out the allowable Dust Accumulation as well as the Measured Accumulation and determine whether there is a deflagration hazard present. There are sheets available for single or multiple accumulation sources, as well as Metric and Imperial. This one can be found at Allowable Dust Accumulation.




Thanks!

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