An Ex certificate is not a label added at the end

For Ex instruments, certification is sometimes treated as the final step: the design is completed, the datasheet is ready, the nameplate is defined, and then “ATEX” is added at the end.

That is not how explosion protection works.

The certification process of an Ex instrument does not start with the marking. It starts with the protection concept.

Will the instrument be designed as intrinsically safe?
Will it be installed in a flameproof enclosure?
Is increased safety applicable?
Is the hazardous atmosphere gas, vapour, mist, dust, or a combination?
Which temperature class or maximum surface temperature can actually be demonstrated?
Is the intended use Zone 0, 1, 2, 20, 21 or 22?
Are cable entries, electronics, seals, enclosure materials and operating conditions part of the same safety concept?

This is where the complexity is often underestimated.

A transmitter, sensor, analyser or limit switch may look like a small component in the installation. For certification, however, it is a complete technical evidence package. The manufacturer must demonstrate that the product meets the relevant Essential Health and Safety Requirements of ATEX Directive 2014/34/EU before it is placed on the EU market. In Great Britain, the equivalent product regime is the Equipment and Protective Systems Intended for Use in Potentially Explosive Atmospheres Regulations 2016. (Interne Markt en Ondernemerschap⁠)

In practice, the technical assessment is commonly based on the EN IEC / IEC 60079 series. IEC 60079-0 defines the general requirements. Other parts address specific protection concepts such as flameproof enclosure “d”, increased safety “e”, intrinsic safety “i” and protection by enclosure “t” for dust atmospheres.

For the end user, the certificate is not a free pass.

The marking must match the hazardous area classification.
The equipment group and category, or EPL, must match the intended application.
The gas group or dust group must match the substance.
The temperature class or maximum surface temperature must match the ignition properties.
Ambient temperature, process conditions and mounting arrangements must remain within the certificate limits.
Any “specific conditions of use” must be read, understood and implemented.

This is where things often go wrong in the field.

An Ex i instrument is considered safe, but the associated barrier, cable parameters and entity values have not been verified.
An Ex d enclosure is opened without sufficient attention to flamepaths, fastener quality or suitable cable glands.
A sensor is installed at a higher ambient temperature than allowed by the certificate.
A dust atmosphere is treated as if it were only a gas application.
An instrument is replaced by a “similar type” without checking the certificate conditions again.

In such cases, the certificate may still exist on paper, but explosion safety is no longer technically demonstrated.

In the EU workplace context, the employer must manage explosion risks under ATEX Directive 1999/92/EC. In the UK, similar duties are placed on employers under DSEAR, the Dangerous Substances and Explosive Atmospheres Regulations 2002, which require risks from dangerous substances, fire and explosion to be assessed and controlled. (HSE⁠)

For selection, installation and initial inspection of Ex electrical installations, IEC 60079-14 is a key technical reference. For inspection and maintenance during operation, IEC 60079-17 is central to keeping Ex equipment compliant in service. (IEC Webstore⁠)

The core message is simple:

Certification does not prove that every later application is safe.
It proves that a specific product, within defined limits, has been assessed according to a defined protection concept.

The real engineering work starts where the certificate meets the installation.

An Ex instrument is only safe when the certificate is correct, the application is correct, and the field installation remains correct throughout its life cycle.

#ATEX #UKEX #IECEx #ExplosionProtection #ExInstruments #IEC60079 #IntrinsicSafety #Exd #Exi #DSEAR #ProcessSafety #IndustrialSafety

Sources used: European Commission ATEX Directive 2014/34/EU, UK Government guidance on the 2016 Equipment and Protective Systems Regulations, HSE DSEAR guidance, IEC 60079-14 and IEC 60079-17.