Hazardous Classification

Please give the details about the difference between materials for EExe and EExd.

What makes the significance of EExe and EExd materials usage?

Thanks & regards.

Hi Bharat,

The difference between Ex d and E e is that any Ex d equipment must be able to withstand an internal explosion of the flammable material without the flame propagating to the atmosphere to the outside, while Ex e equipment does not permit any sources of ignition inside the equipment and flame propagation is not an issue.

Ex d equipment is robust enough not to deform or be otherwise affected by an internal explosion. Accordingly, it usually uses thick metal castings. Ex e equipment is designed only to maintain the required Ingress Protection level of IP54 or better and can be made from any material (metal or plastic) that is suitable for the service. Ex e equipment does not require the large amounts of material that are needed for Ex d.

Both must be selected taking into account issues such as external corrosion agents, effects of UV exposure, or other factors that could act to reduce the integrity of the equipment.

Hope this helps,
Bruce

Futher to add to Bruce

In Ex e (Increased Safety) type of protection, measures are applied to prevent possibility of arc or sparks or excessive temperature inside electric equipments (mostly motors, electrical fittings come with Ex e certification) Further Ex e equipments are permitted to be used in T1,T2 and T3 class only.
Ex e do not permit arc or spark to occur.

While Ex d on the other hand, allow spark or arc to happen, but do not allow for propagation of flame to potentially explosive atmosphere.

Regards
C Potdar

Hi C Potdar,
You state that Ex e equipment is permitted to be used in T, T2 and T3 class only. Can you give me a reference to any IEC standards relating to this as I have never come across this restriction - or is it a local requirement for
your area only?

Cheers,
Bruce.

Hi Bruce,
This is as per Indian Standard 6381 for Ex e equipments. I am not sure but it must be a local requirement.

Regards,
C. Potdar

Thanks for that. Most international manufacturers of repute provide Ex e equipment such as junction boxes rated at T5 or T6, with restrictions on the number of terminals that can be fitted. While there aren't many materials that come into T4, T5 or T6 it would seem strange that you can't use Ex e equipment in these - I would have thought the same temperature rise issues occur with any other method of protection.

Or can you use equipment rated at T4, T5, or T6 as long as the atmosphere is T3 or above?

Bruce.