Zone 1 — Equipment Selection and Inspection Guide
Zone 1 is the most commonly encountered hazardous area classification in industrial facilities. An explosive gas atmosphere is likely to occur in normal operation — during routine activities such as loading and unloading, sampling, equipment opening, or in the vicinity of flanged pipe connections and pump seals.
Equipment Requirements for Zone 1
Zone 1 requires EPL Gb equipment. The protection types approved for Zone 1 include:
| Protection Type | Standard | EPL | Typical Application |
|---|---|---|---|
| Ex d | IEC 60079-1 | Gb | Motors, junction boxes, control stations |
| Ex e | IEC 60079-7 | Gb | Terminal boxes, luminaires, motors |
| Ex ia / ib | IEC 60079-11 | Ga/Gb | Instruments, sensors, transmitters |
| Ex p (px/py) | IEC 60079-2 | Gb | Large control panels, switchboards |
| Ex m | IEC 60079-18 | Gb | Small components, connectors |
The majority of CompEx Ex01/Ex03 assessment scenarios are Zone 1. Equipment is typically Ex d or Ex e, gas group IIB, temperature class T4. Practice selecting and inspecting equipment for this combination — it accounts for a large proportion of offshore and petrochemical plant electrical equipment.
Zone 1 Inspection
Periodic inspection of Zone 1 equipment is governed by IEC 60079-17. Most Zone 1 equipment will require at minimum a periodic Close Inspection — opening and examining the equipment, checking gland thread engagement, verifying internal condition, and assessing any deficiencies found against the X/A/B/C classification system.
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