Zone 1/21 vs Zone 2/22: A Hazardous-Area Device Selection Guide

Quick answer: Confirm the hazardous-area classification before selecting a communication device. Zone 1 and Zone 21 describe gas/vapour/mist or combustible-dust atmospheres that may occur occasionally in normal operation. Zone 2 and Zone 22 describe atmospheres that are not likely in normal operation and would be brief if they occur. The site classification, exact approval marking, certificate conditions, applicable jurisdiction and intended task must all align.

Understand the zone pair

Zone 1 and Zone 2 relate to gas, vapour or mist. Zone 21 and Zone 22 relate to combustible dust. “Zone 1/21” therefore combines two separate hazard contexts, as does “Zone 2/22”; it is not a single universal zone. Never infer the applicable zone from an industry name, room label or an earlier purchase list.

Read the manufacturer’s zone-classification explanation with the site’s approved hazard-area documentation.

IS120.1 and IS120.2: what the public product information states

The manufacturer’s IS120.1 and IS120.2 product pages are starting points only. Product pages can change. Verify the certificate revision, intended use, approved accessory combination and country-specific approval at the point of procurement and deployment.

Five questions before selection

1. What is the verified site classification? Obtain the current classification statement or drawing from the asset owner or competent safety function.
2. Which marking and certificate apply? Match the complete device marking and certificate to the zone, hazard type and governing jurisdiction.
3. What does the work task require? Only after the protection requirement is confirmed, assess communication, positioning, battery and workflow needs.
4. Which accessories will be used? Charging equipment, batteries, cables and carrying systems may form part of the approved-use conditions.
5. Who owns the decision record? Assign responsibility for the site classification, certificate/version evidence, selected configuration and worker instructions.

Decision guardrails

For a verified Zone 1 and/or Zone 21 requirement, investigate only an exact model and configuration whose marking and certificates support that requirement, such as the IS120.1 information set. For a verified Zone 2 and/or Zone 22 requirement, investigate an exact model and configuration whose marking and certificates support that requirement, such as the IS120.2 information set. In either case, a zone label alone is not a licence to use a device or an interchangeability rule.

Frequently asked questions

Does Zone 2/22 mean a safe area?

No. It describes an atmosphere that is not likely in normal operation and would persist only briefly if it occurs. Classification, approved configuration and local controls still apply.

Can a Zone 2/22 device be used in Zone 1/21?

Do not make that assumption. The exact device marking and certificate must match the verified classification and site requirements.

Can a Zone 1/21 device automatically replace a Zone 2/22 device?

No. Review the complete approved configuration, certificate conditions, task needs, local rules and commercial availability.

Next step

To organise product, certificate and work-task inputs before an internal review, contact Wantjoin with the verified site classification and intended use. The final decision remains with the site owner and competent safety or compliance function.