Equipment in Class I, Division II is NOT required to be explosion-proof in the same way as Class I, Division I. Instead, it must be designed to prevent ignition under normal operating conditions.Here's a breakdown of the requirements for each class: Class I, Division I

Equipment must be

explosion-proof. This means that the equipment's enclosure is designed to contain an explosion of a flammable gas or vapor inside it, and to prevent the propagation of flames to the surrounding atmosphere. It must also operate at an external temperature that will not ignite the surrounding gases or vapors. Class I, Division II

Equipment does

NOT need to be explosion-proof. Instead, it must be one of the following: Enclosed and gasketed to prevent the entrance of flammable gases or vapors during normal operation. Intrinsically safe

Designed to not release enough electrical or thermal energy under normal or abnormal conditions to ignite a specific hazardous atmospheric mixture. Intrinsically safe circuits are typically used in conjunction with approved barriers.

Non-incendive

Equipment that does not contain any normally arcing parts or any surface that might exceed the ignition temperature of the hazardous atmosphere.

Suitable for Class I, Division I - this is always acceptable.

Key Differences



Frequency of Hazard

In Division I locations, the hazard is present

continuously, intermittently, or periodically under normal operating conditions, or where failure or rupture of equipment might cause a release of flammable vapors. Division II locations the hazard is only likely to occur in the event of an accidental rupture or breakdown of equipment, such as a container or piping system.

In summary: Class I Division II equipment is designed to prevent ignition of flammable gases or vapors that may be present due to an abnormal event, whereas Class I Division I equipment is designed to prevent ignition in areas where flammable gases or vapors are routinely present. Flag for review