(Your shopping cart is empty)
Explosion Proof vs. Intrinsically Safe
Last Updated: 05/10/2013
First, let's define a hazardous area, or explosive atmosphere? A
hazardous area is a location where flammable vapors, such as gas, or a
concentration of fine dust particles, grains or fibers may be present.
This includes, but is not limited to, chemical and petro-chemical
refineries and process plants, paper mills, sugar refineries, coal
mines, and much more. The use of electronic equipment in a hazardous
area requires strict certification. In an atmosphere where potential gas
vapors or fine dust is present, all electronic devices must be designed
and properly certified according to ATEX and IECEx standards.
Now the comparison... Explosion Proof vs. Intrinsically Safe“Explosion Proof” means
that a housing has been designed, usually of stainless steel or cast
aluminum, to prevent ignition within the explosive area. These housings,
or containers, have the strength to contain an explosion if flammable
gases or combustible particles penetrate the housing where ignition
occurs. These explosion proof housings also prevent any surface
temperatures to exceed ignition temperature of the gases or vapors
within a specific Group rating.
“Intrinsically Safe” is a more
common method of handheld, portable devices. Intrinsic safety is
achieved by limiting the energy and surface temperature of a device
during normal operation, or during foreseeable fault conditions, to an
insufficient level to ignite an explosive environment.
classification rating is earned by passing the rigorous approval process
of a recognized entity. Upon approval, the exact approved hazardous
situations are displayed on the label attached to the unit. The European
ATEX approval is accepted in many parts of the world (checking with the
end-user customer is the only way to be sure outside Europe).
Certification from Factory Mutual (FM) and Canadian Standard Association
(CSA) are the most common approval in North America.
Below defines how certain gases or vapors are classified, and how they are present in a certified area.
Class I: Gases and vapors
Division 1: Gases or vapors are usually present or may be present at any time in sufficient concentrations for an explosion hazard.
Division 2: Gases
or vapors are not normally present and are present only in the event of
a leak in some kind of containment vessel or piping, again in
potentially hazardous concentrations.
Groups A, B, C, D:
Groups of atmospheres categorized by the volatility and/or ignition
temperatures. “A” is the most hazardous and “D” is the least hazardous
group for gases and vapors.
- Group A: Atmospheres containing acetylene.
- Group B: Atmospheres containing hydrogen or gases or vapors of equivalent hazard.
- Group C: Atmospheres containing ethyl-ether vapors, ethylene, or cyclo-propane.
- Group D:
Atmospheres containing gasoline, hexane, naptha, benzene, butane,
propane, alcohol, acetone, benzol, lacquer solvent vapors, or natural