Combustible Dust Testing

Many industrial processes handle solid materials, and in doing so create finely
divided particulates that we commonly call “dusts.” Dusts formed from combustible
solids pose special fire and explosion risks in the workplace. Dusts, by virtue of
their high surface-to-volume ratio and intimate inclusion of air between dust
particles, have distinct ignition and burning characteristics that may differ
significantly from the parent bulk solid. (The portion dust that is air-filled voids
is approximately 35% by volume.) Quantification of ignition and explosion
properties of dusts and dust clouds is an important part of a process hazard
review of areas where combustible dusts are found.

• Dust cloud explosibility data, P_MAX and K_ST, is used to design
  explosion prevention systems including explosion vents and explosion
  suppression systems.
  
  
  
• Minimum explosible concentration, MEC, may be used as elements
  of a fire risk assessment that takes into account all of the factors that are
  pertinent to an assessment of the fire hazard of a particular end use.
  
  
• Limiting oxygen concentration, LOC Dusts, can be of value when
  developing fire and explosion prevention strategies that employ inert
  gases to reduce the concentration of oxygen in a process space.
  
  
• Minimum ignition energy, MIE, of a dust-cloud is primarily used
  to assess the likelihood of ignition during processing and handling.
  The likelihood of ignition is used to evaluate the need for precautions
  such as explosion prevention systems.
  
  
• Ignition temperature of a dust cloud, MIT Cloud. This procedure
  measures the minimum temperature at which a given dust cloud will
  auto-ignite when exposed to air heated in a furnace at local
  atmospheric pressure.
  
  
• Hot surface ignition temperature of a dust layer, MIT Layer,
  measures the minimum temperature at which a dust layer will self-heat.
  This dust ignition characteristic can be used as one element of a fire
  risk assessment that takes into account all pertinent risk factors.
  
  
• Ignition by self heating is a procedure to assess the tendency of
  a bulk dust to undergo spontaneous ignition when exposed to a
  heated environment.