International Standards for Instrumentation in Hazardous Area

When it comes to using instrumentation in hazardous locations (HAZLOC), with atmospheric conditions that could lead to ignition via an electrical spark caused by the mechanics or electronics within the instrumentation, there are different sets of standards and classifications used globally. They are not interchangeable, and all instrumentation must have the proper certification recognized in the area of installation.

Prominent industries that most commonly require HAZLOC certification due to ignitable gases, vapors, or mists are the oil and gas industry (including gas stations) and chemical manufacturing. Any processing facilities, storage vessels, or transfer equipment may be subject to regulations.

Areas that are subject to ignition because of the presence of dust include anything with a fine ignitable particulate matter suspended in the air, like grains or wood.

The different standards are not interchangeable and not apples-to-apples. In the EU, IECEx and ATEX are recognized standards. The standards in North America are referred to as Ex-proof.

Let’s explore the difference between IECEx and ATEX. Here are the highlights for IECEx certification.

• Globally recognized set of standards.
• In some countries it is the only certification required for the product to be recognized as safe (but not sufficient in NA).
• Certification is done through testing by an outside party and not the manufacturer.
• There is a website that lists all the issued certifications so the end user can verify the certification is valid.
• Can be used in part of the process of establishing an ATEX certification by a manufacturer.
• Can also be used as a determining factor in issuing an Ex-proof cert in the US, but is not enough on its own.
• Classification is as follows. First it specifies the type of danger. 1 = mines, 2 = gases, 3 = dust. Then it specifies the frequency of the danger with Zone 0 = always present, Zone 1 = occasionally, and Zone 2 = only in abnormal conditions. Then the third tier specifies the exact gas/dust and the max temperature that the instrumentation is allowed to be present in without danger.

Here are the highlights for ATEX.

• Primarily recognized by the EU
• Not tested by an outside party as the manufacturer self-certifies that it complies with the ATEX standards/requirements.
• The classification system combines gas and dust into one class and mines into a second class. The specification system then follows the IECEx structure for the frequency, the exact dangerous element, and the temperature.

The set of standards used to certify instrumentation as being explosion proof is referred to as Ex-proof. The elements identified by the standard are very similar to IECEx and ATEX, but vary a bit in how they are laid out. Like IECEx, the Ex-proof certification is given by an outside party and not the manufacturer.

Ex-proof follows the standard laid out in the National Electric Code (NEC).

Classification is as follows:

• Type of danger: Class 1 = gas and Class 2 = dust. (There is no separate recognition of mines like IECEx and ATEX.)
• Frequency of danger: Div 1 = always there and Div 2 = occasional/less likely
• Group: the actual gas/dust type
• Temperature considerations: the max temperature allowed for safe operation under the other conditions.

• Not-self certified by the manufacturer.
• Regulated by government bodies/agencies.
• Certification is issued only by government recognized bodies who conduct the testing, such as CSA, UL, and FM certifications.
• Any hazardous location equipment sold into the US or Canada must have the Ex-proof testing and certification. IECEs or ATEX is not sufficient or recognized as a stand-alone certification.

ATEX is a set of standards recognized only within the EU that certifies instrumentation as being safe to operate in hazardous conditions prone to ignitable gas/dust. UL is a certification/agency within the US that tests and certifies that the instrumentation complies with the North American Ex-proof standards.

The US equivalent of ATEX, from the perspective as specifying instrumentation as being safe to operate in hazardous locations, is referred to as “Ex-proof” and consists of four specified elements. The items of danger (class), the frequency of danger (div), and then the actual danger and the max safe temperature for operation. ATEX and Ex-proof are not interchangeable and ATEX is generally not an accepted stand-alone rating the US.