Hazardous Location Protection Method 2

[roydm]

We do a lot of work overseas and often get into a bun fight over the requirements for Hazardous location requirements.
For example pump motors in Class 1 Div 2 Group IIB the client often expects us to provide a motor with Ex d (explosion proof) certification where it only needs to be Ex nA (non sparking).

The different regulatory bodies also make it confusing, IEC, NEC, CEC, Genelec, Atex, Cosha, NFPA, FM

Quite often the country of interest doesn't have their own standards but uses those of another region e.g. China might use European standards

Does anyone know of a good definative document for selecting the method of protection for the different regions.

Thanks in advance.
Roy

 

[ScottyUK]

Roy,

I'm not aware of such a document, but for the example you gave above I can understand that some industries might desire the additional mechanical protection afforded by an Ex'd' enclosure. Where that is the case and the client expects something over and above that required to meet the code requirements then it should be included in the specification.

A lot of people seem to use standards as their specifcation, but the standards generally define the minimum acceptable performance and often provide several methods of achieving that minimum. I don't sympathise with those who can't be bothered to write a detailed spec and then moan when the delivered product doesn't meet their expectations.


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If we learn from our mistakes I'm getting a great education!

 

[dbaird]

Here is a quick reference:

David Baird

Sr Controls Designer
EET degree.
Journeyman Electrician.

 

[roydm]

Thanks David,
I also have a wall chart that the local Pepperl & Fuchs rep gave me, it's quite good but you worry it might be skewed in their favour.

Snce posting I found out the IEC/EN standards 60079 seems to spell out the requirements, there are about 20 different parts so it works out quite expensive to buy sight unseen.

IEC/EN 60079-14 seems to hint at selection, we may start with that.


If anyone has a copy of EN 60079 I would appreciate any comment as to which part is the most usefull.
Thanks
Roy

 

[ScottyUK]

Roy,

I'm not quite sure what you're after here. Zone 2 requirements are fairly easy to meet and there are the widest number of options available - some are cheaper but less robust, others are are costly and more robust. I have access to the 60079 standards and I don't mind having a look once I better understand what you're looking for.


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If we learn from our mistakes I'm getting a great education!

 

[roydm]

Thanks Gentlemen,
I went to the city library, they have most parts of 60079. I came to the conclusion it's pretty useless, lots about lighting and such, not much about motors
We often get into a discussion with clients over class 1 Div 2 requirements. They usually think they need explosion proof motors when all they really need is non-sparking. I thought 60079 might offer some solution to our problems but it's the same old fudge words.
Thanks

Roy

 

[juleselec]

Roy,

I'm with ScottyUK on this one - many clients insist on Ex d or Ex e (or simply avoid Ex nA) in Zone 2 areas for many reasons other than the minimum requirements set by the standards. For example,

- Standardisation of Ex rated equipment (e.g. so that spares are interchangeable)
- Flexibility to move equipment around the plant in the future
- For ATEX-certified equipment, Ex n can be self-certified, which means that a manufacturer can just declare that it complies without third-party testing. Some people get queasy about this idea.
- Mechanical robustness of Ex d equipment (as ScottyUK mentioned)
- Lastly, hazardous area classification is risk-based and of all the protection techniques, Ex n equipment has the highest probability of being an ignition source. So some people may simply want the peace of mind.