Explosion Proof Classifications—What do they Mean?

Andy Metzger Ex, News & Articles

An area in your facility has been classified as a hazardous location and you need an Explosion Proof lift truck, now what? It is important to understand what the hazardous classification means to the safety of your employees and the confidence of having quality, certified equipment for the environment.

An EX forklift manufacturer cannot classify a hazardous area. Only an Authority Having Jurisdiction (AHJ) can determine the hazard classification for any specific location as defined in NFPA 70. Who is considered an AHJ? The AHJ may be a federal, state, local or other regional department or individual such as a fire chief, fire marshal, building official, and electrical inspector are a few examples.

The AHJ will classify a hazardous area based on three designations: Class, Division, and Group. Let’s explore each of these designations.

Classes

Class is used to provide a general definition of the physical characteristics of the hazardous material with which we are dealing. The Three hazardous location classes are:

Class I—Gases, vapors and liquids that can be present in explosive or ignitable mixtures.

Class II—Combustible dust that can be present in amounts that could produce potentially explosive mixtures, or dust of an electrically conductive nature.

Class III—Fibers or flyings that are easily ignitable but are not apt to be suspended in air in such amounts to product ignitable mixtures.

Divisions

The division designation signifies the properties of material responsible for the potential hazard with the likelihood of the hazard actually being present.

Division 1—Locations which ignitable concentrations of flammable gases, vapors, liquids or combustible dust can exist all of the time under normal operating conditions.

Division 2—Locations which ignitable concentrations of flammable gases, vapors, liquids or combustible dust are not likely to exist under normal operating conditions.

Division 1 is the more stringent designation, so EX trucks approved for Division 1 are also approved for Division 2 hazardous locations.

Groups

Group designations are used to selectively group the material by comparatively similar hazardous characteristics.

A, B, C, D – Gases/Vapors. These are grouped by:

  • Ignition temperature of the substance
  • Explosion pressure
  • Flammable characteristics
  • Group A – Acetylene; Group B – Hydrogen; Group C – Ethylene; Group D – Propane, Methane

E, F, G – Dusts. Dusts are grouped by:

  • Combustibility
  • Penetrability between parts
  • Ability to contribute to creation of an ignition source (abrasiveness, electrical, conductivity)
  • Blanketing effect
  • Ignition temperatures
  • Group E – Metal dusts (magnesium); Group F – Carbonaceous dusts (carbon & charcoal); Group G – Non-conductive dusts (flour, grain, wood, plastic)

Summary

Class: Denotes physical characteristics of the materials

Division: Classifies the likelihood of the presence of the hazardous condition

Group: Categorizes the materials by relatively similar hazardous characteristics

All RICO Explosion Proof trucks are approved and labeled to operate in the following hazardous areas:

  • Class I, Division 1 & 2, Group D
  • Class II, Division 1 & 2, Group G

Have questions? Feel free to contact us regarding standards or to request a quote for any of our EX equipment.

RICO Manufacturing also offers free lifetime training with the purchase of an Explosion Proof vehicle called EX University, where you can be trained by our expert engineers, assemblers, and technicians. Schedule hands-on training today!