Define the area classification, Define the area classification -2 – Rockwell Automation 1797-OE8 FLEX Ex Analog Modules User Manual User Manual
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Publication 1797-6.5.1 - May 2005
6-2 Applying FLEX Ex Analog I/O Modules
Define the Area
Classification
Before you can determine what components will make up your FLEX Ex
system, you must define the area in which that system will operate. You must
determine the following:
• classification method
• hazard
• temperature rating
Decide Classification Method
Your application location will usually decide whether the classification method
is Zone or Class/Division, but the system designer may make this
determination. FLEX Ex is certified for Zone method only. Certification is
pending for Division method.
Determine Hazard
Hazard–typically gas, dust, or fibers–is determined by the material being
processed. For example, a coal mine will generally be rated for dust and
methane gas hazards. FLEX Ex is certified for gas hazard only.
Certification is pending for attaching wiring to FLEX Ex I/O modules from a
dust and fiber hazardous area.
Determine Temperature Rating
The spontaneous ignition temperature of the hazard in your application
determines the temperature rating. For example, an application with a
hydrogen hazard may use equipment with a temperature rating of T1 because
hydrogen’s ignition temperature is 550°C. FLEX Ex is certified as a T4
system.