ATEX Guide

Using ATEX Exm outside.

First of all I must emphasize that ATEX EExm encapsulated solenoid coils in general and accordingly the Ex coils are indeed not meant to be subjected to outdoor environmental strain.
Almost all customers know by sound engineering practice that this cannot be achieved without being tested accordingly, however this fact is not stated explicitly in ATEX product documentation.  

How does one know or deduct from the facts given?

a) The IP-Code standard EN/IEC 60529 is not referring to environmental conditions (whereas the American NEMA 250 does: „Outdoor Corrosion Protection Test“, „External Icing Test“...).
Thus it is erroneous to derive from an IP-Code 65 suitability for outdoor applications. Outdoor strains are so diverse that you cannot cope for all conditions prevailing at the possible geographical places with a simple IP test done. No way.
You will find that the EN/IEC 60068 series of standards has numerous parts that deal with those kind of strains, none of them is required for Ex certification.

b) It is true that water protection is required by the Ex standards, some require IPx5, IPx4 but even IPx0 is allowed, see Ex 'e' EN 60079-7. This is not absolute watertightness and we can deduct that water is not a direct cause for arcing even when in contact with blank current carrying parts (as allowed in  'e' EN 60079-7) .
You cited "A protection concept where by equipment that could potentially cause an ignition is encapsulated within a compound or resin so as to prevent contact with the explosive atmosphere". Yes, it is the explosive atmosphere that must be kept out, this is not water.

c) Note that the tests for IPX5 are very short regarding the period of time that water is applied when compared to water strains outdoor.
Water creeping into the coil would cause creeping currents therein. Small amounts will evaporate by thermal energy. This would do no harm.
Being exposed frequently and long lasting to water will lead to degradation of the isolating features with a resulting failure thereof and further current rise meaning excess power and heat in the coil.
In this respect water is critical must be avoided for a reliable installation.
The possible fault of a failing isolation within the coil is covered by the mandatory application of a suitable current fuse, see certificate and operating instructions. Please remind your customer in case you doubt that he follows the prescriptions made.

d) 'Outside usage is possible but not uncovered' had been mentioned below.
Well, no. Outside usage does mean more than rain from above as explained earlier, a cover may be helpful in some respect but is not considered to be sufficient.

These are our points, though very technical I hope you will find it explanatory.

The Fuel or Chemical ignition temperature depends on its consistency and its nature. The ignition temperatures for various types of Fuel or Chemical are available from reference tables.