Correlation between Ingress protection & Explosion protection

The correlation is a little more complicated than you first might expect. For example flameproof (Ex d) enclosures are not necessarily weatherproof (especially if they use a flush metal on metal seal for the lid and are mounted horizontally).

Generally you need to consider Ex and IP ratings separately (or more importantly Ex classification first, then weatherproofness (is that a word) second), however as a general rule Ex rated enclosures will have an equivalent dust rating (by general inspection using common sense) of either IP5X or IP6X and a water rating of IPX4 (or better), but this is only due to the way the Ex enclosures are constructed (using the different techniques to provide protection) to comply in the hazardous areas they are designed for.

In the end it really depends on the type of protection method the Ex enclosure uses (eg-pressurisation, oil immersion, etc), the application it is used in, and the area it is installed in.

Oh, as a side note, I am in the process of becoming certified to sign off on hazardous area equipment and installations as part of my job and my office is currently full of IEC hazardous area standards.

Mani,

Jack is right: there is no relation between IP classification and EX.

If you would dive into the final solutions you will find a strong correlation between EX and IP (this direction). You will see that EX e junction boxes have a minimal protection of IP56. This is imposed by the regulations for EX.

EX d does not comply to this: it is even worse as each d style enclosure has a predefined pressure relief path which prevents water tightness.

One rule of thumb: you can't take a box IP xx and assume that it will comply to a certain EX level as the IP is realised on the level of enclosure and EX is realised inside the enclosure. (d is the exception)

Ask specialists to help you out, instead of defining a wheel. IEC is a good base standard.

Gwen

Explosion proof types have to contain and slowly release an internal explosion event while cooling exhausted gases over a flamepath (heatsink), This requires a certain controlled gap in the cover to exhaust any built up pressure within enclosure.

This is the d style of protection.

Modern world has passed this stadium: we don't have explosions any more. (e style)