ATEX is the European framework for equipment and workplaces where flammable gas, vapour, mist or dust could ignite. The name comes from the French Atmosphères EXplosibles. For offshore and marine crews the practical question is simple: which zone are you working in, and is your gear certified for it?

This guide explains the zones, how to read the marking on a device, and what to check before you buy. If you already know what you need, see our range of ATEX safety equipment.

What ATEX actually covers

ATEX is two EU directives that work together:

  • Directive 2014/34/EU sets the rules for manufacturers. Equipment intended for explosive atmospheres must be designed, tested and marked to a defined level of protection.
  • Directive 1999/92/EC sets the rules for employers. They must assess explosion risk, classify hazardous areas into zones, and use suitable equipment in each zone.

That is why you hear both “ATEX equipment” and “ATEX zones”. The zone describes the place. The equipment rating describes what the device can safely do in that place.

An explosion needs fuel mixed with air in the right proportion, plus something to ignite it. ATEX equipment is built so that it cannot be that ignition source, whether through a spark, a hot surface or static, within the limits of its rating.

The three gas and vapour zones

Zone The explosive atmosphere is… Often cited as Typical examples Equipment category
Zone 0 Present continuously or for long periods More than 1,000 hours a year Inside fuel or cargo tanks, inside process vessels Category 1G
Zone 1 Likely to occur occasionally in normal operation 10 to 1,000 hours a year (approximate illustration, not a formal regulatory threshold) Around tank vents and openings, pump rooms, some enclosed spaces next to cargo or fuel tanks Category 2G (or 1G)
Zone 2 Not likely in normal operation, and brief if it does occur Under 10 hours a year Wider areas around the hazard, such as open deck near cargo or process equipment Category 3G (or 2G, 1G)

The examples are illustrative. The zone for any real space comes from the hazardous area classification drawing for your vessel or installation, not from a table like this one.

The rule of thumb is that equipment rated for a more demanding zone can be used in a less demanding one, but not the other way round. A Zone 1 device can go into Zone 1 or Zone 2. It cannot go into Zone 0.

Dust zones

The dust equivalents are Zones 20, 21 and 22, matching Zones 0, 1 and 2 in the same order. They apply wherever combustible dust can build up in the air, such as bulk grain, coal, sugar or fertiliser cargoes. Dust equipment is marked with a D instead of a G.

How to read an ATEX marking

A typical marking looks like this:

CE | Ex (hexagon) | II 2 G | Ex ib IIC T4 Gb

Part What it tells you
II Equipment group II, meaning surface industries (group I is mining)
2 Category 2, suitable for Zone 1 (and Zone 2)
G Rated for gas, vapour and mist. D would mean dust
Ex ib The protection concept, here intrinsic safety, level ib
IIC Gas group. IIC is the most demanding and covers hydrogen and acetylene. IIB covers ethylene. IIA covers gases such as propane and methane
T4 Temperature class. The surface will not exceed 135 °C, which must stay below the ignition temperature of the gas
Gb Equipment protection level for Zone 1

If any one of those does not match your site, the device is not suitable, even if it carries an Ex mark.

Who decides the zone?

Not the manufacturer, and not the person buying the equipment. The owner or operator carries out the hazardous area classification, on a vessel usually together with the class society. The manufacturer certifies what its equipment is suitable for. Your job is to match the two.

Ships also have their own rules, such as SOLAS and class society requirements for hazardous areas on tankers. In practice, operators and charterers routinely specify ATEX or IECEx certified portable equipment for crews who enter classified areas.

Why it matters for man overboard and personal safety gear

A personal locator beacon, AIS beacon or lifejacket light has a battery, a transmitter and a switch. That is enough to ignite the wrong atmosphere. Crews on tankers, FPSOs, platforms and in oil and gas terminals cannot carry standard consumer or recreational devices into classified areas.

As an ATEX safety equipment supplier, we carry certified options across several product types:

A Zone 2 beacon is not a Zone 1 beacon. If your crew might enter Zone 1, buy for Zone 1. You can compare the full range in our AIS personal locator beacons category.

Certification also depends on how the device is looked after. We are an authorised service centre for both sMRT beacons and WeatherDock beacons, and you can review our inspection and maintenance options before planning your schedule.

What to check before you buy

  1. Your zones. Get them from the hazardous area classification, or from the client or operator who requires the equipment.
  2. Category and protection level. The marking must cover the highest-risk zone the device will enter.
  3. Gas group and temperature class. The group must cover the gas on site, and the T class must stay below that gas’s ignition temperature.
  4. The certificate. Ask for the certificate number and the instructions. A number ending in X means there are special conditions of use.
  5. Special conditions. ATEX devices often have rules on battery type or on charging in a safe area only. Make sure your crew can follow them.
  6. Servicing. Confirm who is authorised to service the device without voiding certification.

Frequently asked questions

Is ATEX mandatory on ships? ATEX is EU law for equipment placed on the EU market and for workplaces in the EU. Vessels are mainly governed by flag state and class society rules, but ATEX or IECEx certified equipment is widely specified for crews working in hazardous areas.

Is ATEX the same as IECEx? No. They are related but different. Read our guide to ATEX vs IECEx.

Does ATEX apply in the United States? The US uses a different system based on the National Electrical Code. See ATEX vs US hazardous location ratings.

Can I use Zone 2 equipment in Zone 1? No. Equipment must be rated for the zone it enters or a more demanding one.

Not sure which rating you need?

Marine Rescue Technologies is a family-run business in Florida with more than 25 years of offshore safety experience, and we offer complimentary marine safety consulting. Contact us with your zones and application and we will help you match the right equipment.