Hazardous area certification is the one specification where getting it wrong is not a commercial problem but a safety and legal one. It is also the one most often reduced to a single line on a purchase order that reads only ex proof.
This is the short version a buyer needs in order to ask the right questions.
Zones describe how often an explosive atmosphere is present
Gas zones and dust zones are numbered separately. The lower the number, the more of the time the hazard is present, and the more demanding the protection required.
- Zone 0: explosive gas atmosphere present continuously or for long periods
- Zone 1: likely to occur in normal operation
- Zone 2: not likely in normal operation, and only for a short period if it does
- Zone 20, 21 and 22: the same three bands for combustible dust
ATEX and IECEx are two routes to the same result
ATEX is the European Union scheme and is mandatory for equipment placed on the EU market. IECEx is the international scheme, based on the same IEC standards, and is widely accepted across the Gulf.
In practice many operators in Qatar specify IECEx, and much of the equipment carries both. What matters is that the certification covers the zone, the gas group and the temperature class of the installation, not which scheme issued it.
Reading the nameplate
A marking such as Ex db IIC T4 Gb tells you the protection concept, the gas group, the temperature class and the equipment protection level. Two parts deserve particular attention.
The gas group must cover the gases present. IIC is the most demanding and covers hydrogen and acetylene, IIB covers ethylene, IIA covers propane. Equipment certified for IIA cannot be used where IIC is required. The temperature class caps the maximum surface temperature: T4 is 135 degrees C, and must sit below the auto ignition temperature of the gas.
Ambient temperature is the trap in a Gulf installation
Most certificates state an ambient range, commonly 20 to 40 degrees C. Summer ambient in Qatar routinely exceeds that, and equipment operated outside its certified ambient range is outside its certification even though nothing about the marking has changed.
Ask for the certified ambient range explicitly, and specify extended range equipment where the installation is outdoors and unshaded. This is the most common gap we see when reviewing an existing installation.
What to send when you request a quote
The zone, the gas group, the temperature class, the required ambient range and the ingress protection needed. With those five, equipment can be matched to the certificate rather than to a description.
Need this specified for your site?
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