A - Whilst the IP rating is a key part of 'protection by the enclosure' for dust ignition protection, the standards that apply (EN 61241-0 and EN 61241-1) require other tests such as thermal endurance on plastic parts of the enclosure and impact testing. The tests have to be completed in order and the thermal endurance test is an aging test - 80°C and 90% RH for 4 weeks, so this can make plastic enclosures more brittle as well as causing compression set on the seals.
So it isn't quite enough to rely on an IP65 enclosure, although this could be a good starting point.

Q - Can i connect pre atex equipment to atex equipment? what is the criteria that must be followed? (this is for M1 and M2 Group 1 mining equipment)

A - There should be no problem connecting pre-ATEX and ATEX equipment. For intrinsically safe equipment the overall system would need to be in compliance with EN 60079-25.

Q - Can i repair atex equipment with pre atex spares (again M1/M2 GROUP 1)

A - Repairs are not covered by the ATEX product Directive, they come under the ATEX 137 use Directive (DSEAR). It is possible to fit pre-ATEX or non-ATEX spare parts to ATEX products, but the user has to be satisfied that the repaired or modified product is fit for use. EN 60079-19 can be referred to, but this will require the repair of modification to be in compliance with the original certification standards.

For some equipment, repairs can be straightforward. For example a bearing or seal assembly on a motor can be replaced with a like for like part of equivalent or better rating without any issues arising. For intrinsically safe equipment there could be a problem with exchanging a battery for a different type not listed on the certificate, therefore this would not be recommended without first seeking advice.

For increased safety terminal boxes, replaced terminals that are certified against earlier editions of the standard would not have had a pull test conducted on them, therefore the standard of safety for the repaired product would not be the same as the original. This may not give rise to a significant additional risk.

I have assumed that the pre-ATEX certified spare parts are available from stock (i.e. have been placed on the market and bought before the June 2003 deadline for ATEX compliance).

A - "Increased safety equipment (Ex e) is a higher level of protection than Type n. Both standards cover similar products, although you will not find semi-conductors marked Ex e because this type of protection recognises a single fault condition could occur. The failure mode of semi-conductors is not known, but could be predicted as 'optimum resistance' for the load and therefore where the supply has significant energy this will lead to an ignition source.

Type n equipment is used in Zone 2 and has a corresponding lower level of protection than increased safety. For Type n equipment it is sufficient for them to be 'safe in normal operation'. As semi-conductors can be assumed not to fail in normal operating conditions they are permitted under this type of protection.

Both protection concepts can be used to protect the more common items of equipment, for example junction boxes, luminaires and motors. Any power electronics that are needed in increased safety equipment will be protected by another type of protection, for example an electronic ballast for a luminaire could be encapsulated (Ex m) or housed in a flameproof enclosure (Ex d). In a Type n luminaire the ballast may not have additional protection, provided it has no potentially sparking parts.

In short, it isn't easy to tell the two apart, except for marking differences, other than the presence, or not, of semi-conductors in the equipment."

A - This is possible if the customer is the original manufacturer. To upgrade non-ATEX equipment to ATEX, the manufacturer will need to apply to a Notified Body for an ATEX upgrade. That body will then assess the equipment against the relevant EN 60079 series standards and issue the relevant certification.

If your customer is not the original manufacturer, he does not own the design rights to the equipment (and therefore has no certification drawings etc.) However, if the equipment was bought prior to the ATEX deadline, it is suitable for use without having to be ATEX certified as the equipment was put on the market and put into service prior to the deadline on July 2003.

A - Whilst there are no future plans for an alternative directive to ATEX within the EU, there will over time be changes to the technical standards that are used to gain certification. Recently, the EN 50000 series of standards were superseded with EN/IEC 60079 series for example.

Once certified equipment is placed on the market and installed, any new standards that are issued will not retrospectively apply to it. There have been quite a few changes to standards over the last few years, with more to follow, therefore manufacturers should check to see if any changes affect the products they are continuing to manufacture. The ATEX Directive requires manufacturers to utilise the latest technical knowledge, therefore any new restrictions in the standards should be considered with a view to updating the certification.

A - Some notified bodies will provide an email update on your selected standards, but this will only inform you that a new version has been issued. The Foreword of EN standards includes details of clauses where changes have been made. Others, such as Sira, can provide a comparison between standards or technical support for specific product evaluation.

A - Response from Engineer:

- Please note that the answer is based upon our engineer's own experience and is dependent upon how the manufacturer is stating compliance to the standards. It is therefore our opinion rather than anything pertaining directly to a certification problem:

"When doing mechanical proof torque tests, upon dismantling I know that certain certification bodies would have failed the gland if the armour ring was distorted, broke or damaged in anyway if the ring was used for clamping in accordance with the standards. I also now look for the same. With regards to the armour ring being loose on dismantling and providing clamping, this is not a failure as there is no requirement to review this within the standard as long as the ring (as applicable) clamps the cable on assembly, when expected to do so.

Also, It is not always used for clamping, it may be providing earthing properties only (no requirements in the standards for test). In this case the gland should be re-terminated in accordance with the manufacturers instructions. If the ring has broken due to stresses from weather or installation environment this should have been taken care of by the appropriate selection of gland with some caveats specified within the instructions covering some of the ATEX EHSR's".