Zone 1 Ex pyb Marking for Purging & Pressurisation Techniques for Hazarodus Locations

Published 29 May 2020

Ex pyb Marking for Purging and Pressurization Technique for hazardous use in Zone 1“.

In accordance with standard IEC 60079-2, “Ex pyb” marking provides Equipment Protection Level (EPL) Gb with EPL Gc internal to the pressurized enclosure. It simply means the internal components must be evaluated against hazardous location  Zone 2.

“Zone 2” products require IP54 rated enclosure and in some cases the enclosure will need to be provided in end-use application (i.e. Zone 2 Power Supply). The positive pressure inside the pressurized enclosure will provide a safe area inside and prevent ingress of dust and water into the enclosure.

The internal “Zone 2” products must not remain energized when the the type of explosion protection “pyb” is not in operation as there is no IP54 enclosure in effect.

In case of use of batteries inside enclosure which remain energized, Annex G and H of IEC 60079-2 provide additional safety requirement.

The Ex marking is “Ex pyb IIC T4 Gb” without any Zone 2 markings that are used for internal components. Do you think a QAR with Zone 2 protection technique(s) is needed while the marking in IECEx CofC shows only EPL Gb?

Information Courtesy

Author Behzad Nejad, P. Eng. (Hazcon)

Director & Consulting Engineer at Hazcon Inc.; Hazardous Locations Consulting Services; IECEx, ATEX, CEC & NEC

Specializing in the design, safety and approval of electrical equipment for hazardous locations. 

Mr. Nejad has over 15 years of experience as an Electrical Engineer and is a sought after professional in the hzardous area and explosion protection industry. He is fully-qualified at the advanced level of all hazardous locations protection techniques including Intrinsic Safety & Non-incendive, Explosion Proof & Flame proof, Increased Safety, Non-arcing, Purging and Pressurization, Encapsulation, Optical Radiation, and Dust-tight enclosures. Mr. Nejad’s tenure in the industry includes  six years at the CSA certification agency, working closely with manufacturers (Emerson, GE, ABB, Siemens, Endress-Houser, VEGA etc.) as a technical and certification engineer for Hazardous locations equipment.


The opinions expressed in this article are those of the author.

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