{"id":4582,"date":"2026-09-18T08:20:26","date_gmt":"2026-09-18T08:20:26","guid":{"rendered":"https:\/\/exlontu.com\/?p=4582"},"modified":"2026-09-18T08:22:42","modified_gmt":"2026-09-18T08:22:42","slug":"zone-1-vs-zone-2-explosion-proof-ac","status":"publish","type":"post","link":"https:\/\/exlontu.com\/en_gb\/zone-1-vs-zone-2-explosion-proof-ac\/","title":{"rendered":"Zone 1 vs Zone 2 vs Zone 21: Choosing the Right Explosion-Proof AC"},"content":{"rendered":"

Zone 1 vs Zone 2 vs Zone 21: Choosing the Right Explosion-Proof AC<\/h1>\n

\"zone<\/p>\n

Hazardous areas are not all the same. The risk level differs from zone to zone. Consequently, the equipment rules differ too. Many buyers ask about zone 1 vs zone 2 air conditioner selection. This article explains the differences clearly.<\/p>\n

We cover gas zones and dust zones. In addition, we show how the zone drives certification, marking and price. Finally, we include a comparison table and a buyer checklist. For a broader overview, read our explosion-proof air conditioner guide<\/a>.<\/p>\n

Zone Classification Basics<\/h2>\n

The IEC 60079 series<\/a> defines hazardous area zones. Gas and vapor zones include Zone 0, Zone 1 and Zone 2. Dust zones include Zone 20, Zone 21 and Zone 22. The zone number reflects how often an explosive atmosphere appears.<\/p>\n

Zone 0 means a flammable atmosphere is present continuously. Zone 1 means it appears occasionally in normal operation. Zone 2 means it appears rarely and only for short periods. Similarly, Zone 20, 21 and 22 follow the same logic for dust clouds.<\/p>\n

Most air conditioning applications sit in Zone 1 or Zone 2. Therefore, this article focuses on those two. However, we also cover Zone 21 because dust hazards are common in storage and processing.<\/p>\n

Zone 1 vs Zone 2: Key Differences<\/h2>\n
\"zone
Match the equipment category to the zone before installation.<\/figcaption><\/figure>\n

Zone 1 demands a higher level of protection. Explosive atmospheres may exist during normal operation. Therefore, the equipment must prevent ignition under likely fault conditions. Zone 2 permits a lower protection level. Flammable atmospheres appear rarely and briefly.<\/p>\n\n\n\n\n\n\n\n\n\n
Factor<\/th>\nZone 1<\/th>\nZone 2<\/th>\n<\/tr>\n<\/thead>\n
Atmosphere presence<\/td>\nOccasionally in normal operation<\/td>\nRarely, for short periods<\/td>\n<\/tr>\n
ATEX equipment category<\/td>\nCategory 2G<\/td>\nCategory 3G<\/td>\n<\/tr>\n
Typical protection<\/td>\nFlameproof (Ex d), Ex e, Ex i<\/td>\nEx n, Ex e, Ex i<\/td>\n<\/tr>\n
Marking example<\/td>\nEx d IIB T4<\/td>\nEx nA IIB T4<\/td>\n<\/tr>\n
Relative cost<\/td>\nHigher<\/td>\nLower<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

As a result, a Zone 1 unit costs more. It needs heavier enclosures and stricter testing. Meanwhile, a Zone 2 unit is lighter and cheaper. However, you cannot use a Zone 2 unit in a Zone 1 area.<\/p>\n

Zone 21 and Dust Hazards<\/h2>\n

Dust zones create different risks. Zone 21 covers areas where a dust cloud appears occasionally. Flour, coal, metal powder and chemical dust all qualify. In these areas, surface temperature matters as much as spark control.<\/p>\n

Dust can settle on hot surfaces. Over time, it forms layers that insulate and ignite. Therefore, the unit’s surface temperature class must stay below the dust’s ignition temperature. In addition, enclosures need dust-tight seals (IP6x).<\/p>\n

Some units carry dual certification for gas and dust zones. For example, an air conditioner marked Ex d IIB T4 and Ex tb IIIC T130 \u00b0C can serve both Zone 1 and Zone 21. Consequently, dual-rated units simplify site stock.<\/p>\n

How the Zone Choice Affects Air Conditioner Selection<\/h2>\n

The zone determines the equipment category under the ATEX Directive 2014\/34\/EU<\/a>. Zone 1 requires Category 2G equipment. Zone 2 accepts Category 3G. The marking on the nameplate must match your area classification.<\/p>\n

In practice, many buyers choose Zone 1-rated units even for Zone 2 areas. This approach offers flexibility. The same unit can move between areas without re-qualification. In contrast, it costs more upfront. Therefore, weigh flexibility against budget.<\/p>\n

Also consider gas group and temperature class. Gas groups IIA, IIB and IIC represent increasing hazard. T-classes range from T1 to T6. Match both to the site’s gas analysis. For example, hydrogen needs IIC and often T4 or better.<\/p>\n

Common Misconceptions About Zones<\/h2>\n

Myth one: Zone 2 needs no certification. In fact, Zone 2 still requires Category 3G equipment. The protection level is lower, but the rules remain mandatory.<\/p>\n

Myth two: a higher zone rating always costs more. While true in general, dual-rated units often simplify stock. Consequently, the overall project cost may fall. Therefore, compare the total picture.<\/p>\n

Myth three: dust zones are easier than gas zones. In contrast, dust layer ignition adds a hidden risk. Surface temperatures and cleaning schedules demand real attention.<\/p>\n

Worked Example: Choosing a Unit<\/h2>\n

Consider a pump shelter classified Zone 2, IIB T3. A Category 3G unit with Ex nA marking fits. Therefore, choose the lower-cost Zone 2 model. This decision keeps compliance and budget in balance.<\/p>\n

Now consider a paint mixing room in Zone 1, IIB T4. This area needs Category 2G equipment. Choose a flameproof unit rated Ex d IIB T4. As a result, the selection follows the zone directly. In practice, this zone 1 vs zone 2 air conditioner logic applies to every project.<\/p>\n

Buyer Checklist for Zone-Based Selection<\/h2>\n