Ah ATEX and the sound of wailing and gnashing of teeth!
0) are you a user or manufacturer?
1) the pumps, are they in an ATEX zoned area?
2) if yes which one? (gases 0, 1 or 2, dust 20, 21 or 22)
3) what drives the pump?
4) etc etc etc.
WHAT CAN YOU DO ??
a) There are guidelines for the ATEX directive downloadable as a pdf from the EU website
b) In the UK there are guidelines downloadable from the DTI web site.
c) In the UK you can also enquire from the HSE. Try the Bootle office as thats where the top ATEX people are.
d) You can pay for professional guidance from consultants.
It is confusing as the regulations are only now being thought about seriously and as with other directives I'm sure their application will start to change slightly as problems occur.
It won't be easy, sorry. You just have to do your best.
Oh and by the way, this is common European legislation and as with all COMMON EUROPEAN LEGISLATION the interpretation ends up anything but common across Europe!