Extended ATEX could trap design engineers

With the ATEX regulations just past their first birthday, Nigel Smith of Hoerbiger-Origa reckons mechanical engineers need to sit up and pay attention.

With the ATEX regulations just past their first birthday it is becoming increasing apparent that not everyone has recognised their full extent, leaving many engineering companies, end-users and the individual engineers they employ exposed to possible prosecution.

The electrical fraternity are largely up to speed, but mechanical engineers need to sit up and pay attention.

The new ATEX regulations were introduced last year to harmonise standards across the EU concerning safety in potentially explosive environments.

They were based in part on now-superseded laws relating to equipment that has potential to produce sparks, namely motors, relays, contactors and other electric equipment.

It is perhaps not unexpected that electrical engineers embraced and understood the new regulations.

However, what an awful lot of engineers seemed not to have noticed is that ATEX expands the requirements to apply them to other nonelectrical components that are sources of heat, static electricity and other potentially dangerous side effects, such as adiabatic compression and impact-created sparks.

To this list you can also add bearings that could run hot (even if only under extreme circumstances), moving parts that are in contact with other components, open fires and naked flames, welding equipment, heat treatment equipment, heatsinks, lamps and bulbs.

Many engineering components previously not subject to specific regulation will now fall under ATEX.

Typically this could include pneumatic actuators: their control valves may be solenoid operated so can both spark and heat up; they have several instances of parts moving in close proximity, which (theoretically) could lose lubrication and heat up or spark; the compression of air in the end-of-stroke cushions could cause local heating; they are often used in association with shock absorbers which dissipate energy in part by creating heat.

Similar arguments can be made for linear actuators (particularly rack and pinion but also screw and belt versions), robotic end effectors and any number of other every day engineering components.

Like most modern legislation, ATEX is worded generally in order to cover as many different technologies and situations as consistently as possible.

It is up to engineers and their customers to interpret the regulations for their own situation.

And they should bear in mind that if there is a case brought against them their interpretation will be held up for scrutiny in court and compared with other possible interpretations.

The best way to stand up to such investigations is to have a comprehensive paper trail of documentation, keeping a copy yourself and giving another to the customer.

If this is compiled into a safety file it can include documentation from all relevant suppliers and easily be updated if a machine is reconfigured or its working environment changed.

It should be noted that ATEX refers to the working environment in which machines and components are used, rather than offering blanket certification of particular equipment.

It is also significant that there is a changeover period; initially only new machines have to comply, but before 2006 existing machines will also come under the ATEX umbrella.

Many engineers have felt under the cosh for a decade or more as ever more onerous legal responsibility is heaped on them, but ATEX now makes it clear the responsibility for defining the risk lies firmly with the end user.

It is up to the end-user to define the risk category of the area in which equipment is deployed, and this is best done by complying with the standard Zone 0, 1, 2, 20, 21, 22 framework.

(In basic terms Zones 0 and 20 are for frequent risk, Zones 1 and 21 for occasional risk, and Zones 2 and 22 are for rare risk, each zone pair referring to gas and dust risk, respectively).

Therefore suppliers to end users who do not advise on classification of risk areas cannot be held responsible.

If the end-user asks for advice on risk assessment, they should be referred to an independent safety consultant.

If the end-user or consultant specifies the risk area classification or characterises risk definition, the machine builder's first duty is to ensure that only components that conform to the specification are used.

This is best done by selecting appropriately certified components from reliable suppliers.

The machine builder also needs to be aware of creating risks other than through individual components.

For instance cracks and crevices where dirt and oil could collect are potential dangers; poor air flow, ventilation or cooling could allow local heat to build up; moving parts that could collide, even if under very unusual circumstances, are a spark risk; safety valves should be arranged to vent in a considered, failsafe way etc.

ATEX is a powerful new law, designed to improve industrial safety in potentially explosive environments.

If it is understood by component manufacturers, machine builders, end users and everyone else in the supply chain, it is not onerous; instead it provides a framework which allows relatively easy identification of an environment's potential risk and a procedure for minimising that risk.

But if you are negligent in assessing risk against ATEX criteria, it is possible that you will be the one left carrying the can if there is an accident.

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