ATEX Assemblies – a basic introduction

As a notified body, we often get questions about the requirements for assemblies. To fully understand the concept of assemblies, we need to look at how “equipment” is defined in the ATEX Directive 2014/34/EU: 

Equipment means “machines, apparatus, fixed or mobile devices, control components and instrumentation thereof and detection or prevention systems which, separately or jointly (…) which are capable of causing an explosion through their own potential sources of ignition.” The key words here are separately or jointly.

Explosion risk assessment of assemblies can be complex. Assemblies may consist of equipment of different categories and be intended for potentially explosive atmospheres having different physical characteristics. They may also include parts other than equipment such as components and protective systems. 

Let’s look at a basic example from the ATEX Guidelines where a combination of a pump and an electric motor is considered.  

Single products 

If the electric motor is an integral part of the pump, and the pump and electrical motor cannot be assessed separately with respect to explosion risk, the unit as a whole has to undergo the conformity assessment procedure of electrical equipment. The EU declaration of conformity is supplied for the pump and electric motor as a single product. 

Separate or single products? 

In some cases, the pump and electric motor can be considered separately. If there are no additional ignition hazards as a result of assembling the pump and electrical motor, the unit as a whole does not need to be considered a single product.   

• The pump must undergo the conformity assessment procedure of mechanical equipment. An EU declaration of conformity is supplied for the pump. 
• The electrical motor must undergo the conformity assessment procedure of electrical equipment. An EU declaration of conformity is supplied for the electric motor. 

The manufacturer can also choose to supply the pump and electrical motor with one EU declaration of conformity for the assembly as a whole. If the assembly consists of ATEX compliant products and there are no additional ignition hazards as a result of assembling the pump and electric motor, the manufacturer draws up a technical file, affixes the CE marking and signs the EU declaration of conformity. 

This procedure does not necessarily require the involvement of a notified body. Furthermore, if the manufacturer is in any way uncertain as to how to undertake such an assessment, technical advice should be sought. 

When to involve a notified body

The assembly must undergo the complete conformity assessment procedure appropriate for the category if: 

• Assembling the pieces of equipment results in additional ignition hazards. 
• Some of the items are not ATEX compliant. 

Depending on the equipment category, this may require the involvement of a notified body. For more information about assemblies consult the ATEX Guidelines, or you can contact Gexcon Certification at certification@gexcon.com for assistance.