The National Fire Protection Association has recently revised its Standard on the Fundamentals of Combustible Dust – NFPA 652. According to the standard’s 2019 Edition, all dust collection systems, new or existing, are subject to a dust control plan as a part of an overall Dust Hazard Analysis (DHA). If you need to add or renovate a dust collection system as part of your DHA, there are many criteria that go into the design of any dust collection system. In this new three-part series on Dust Collection System Design, we will cover three of the key design criteria that will help you get the most out of your investment in a dust collection system. The first part will discuss how to determine capture velocity.
Capture Velocity
The starting point for a dust collection system is determining the air velocity required to capture the dust particles. The recommended capture velocities from the American Conference of Governmental Industrial Hygienists has a wide range from 50 FPM up to 2000 FPM. The two factors that go into determining the appropriate capture velocity are the weight and velocity of the dust particles. Lighter particles, such as paint spray or flour dust, use lower velocities, while heavier particles such as metal turnings or blast dust require higher velocities. Slow moving particles such as those released by container filling activities will require slower capture velocities, while particles released by a moving conveyer belt will require higher velocities. Starting the design process with the appropriate capture velocity will save you from over or under sizing the dust collection system.
In Part 2 of this series, we will discuss the second key design criteria which is transport air velocity.