What are the usage locations for EX D IIC and EX D IIB respectively?
December 14, 2025
What are the usage locations for EX D IIC and EX D IIB respectively?
severe, like Hydrogen & Acetylene (chemical labs, gas plants), where IIC-rated gear can also protect IIB/IIA zones due to its robust flameproof (Ex d) design.
Ex d IIB (Flameproof Group IIB)
Gases: Ethylene, Hydrogen Sulfide (H₂S), Coke Gas, or similar hazards.
Risk Level: Medium.
Typical Locations: Petrochemical plants, refineries, areas with significant ethylene or similar gas risks.
Ex d IIC (Flameproof Group IIC)
Gases: Hydrogen, Acetylene, or gases with even smaller molecules and higher explosion risk.
Risk Level: High (most severe gas group).
Typical Locations: Chemical laboratories, gas plants, hydrogen production/storage facilities, and any area with extremely volatile gases.
Key Takeaway
Hierarchy: IIC is the highest/most severe group; IIB is medium; IIA is lowest.
Compatibility: Equipment rated for IIC is generally safe to use in IIB or IIA locations. However, IIB equipment is not safe for IIC areas because its flameproof enclosure might not contain the smaller hydrogen or acetylene molecules.