At the previous OSHA combustible dust stakeholder meetings there was considerable discussion about how OSHA should define combustible dust and how that definition could or should be used to determine what types of facilities would be covered under the scope of an OSHA standard.
The consensus standards addressing combustible dust use varying definitions. Under its National Emphasis Program (NEP) for combustible dust, OSHA uses the dust deflagration index – measured in Kst – to determine the relative explosion severity compared to other dusts. The larger the value for Kst, the more severe the explosion. OSHA currently treats any dust with a Kst > 0 as combustible. Some stakeholders have objected to this approach, arguing that low Kst dusts should not be treated as combustible.
What do you think? How should OSHA define combustible dust? Should OSHA rely on the Kst values? If so, are you aware of any data or information showing that low Kst dusts do not present an explosion, deflagration or flash fire hazard to workers?
Alternatively, should low Kst dusts be treated differently, requiring less stringent controls than higher Kst dusts? Are there other variable cutoffs (e.g., particle size distribution, Pmax, MIE) that OSHA should use in determining whether or how to regulate a dust?