What is the difference between Weatherproof encloser and Flameprof encloser for instruments? What are the criteria for Weatherproof enclosers? How they are correlate with IP class and NEMA encloser types?
Flameproof / Explosion proof equipment
The equipment is simply contained in a heavy protective enclosure, usually made of die cast steel, occasionally plastic. If heat or sparks from faulty equipment within the enclosure ignite flammable gas present with it the resulting explosion is contained within the enclosure.
In North America metal conduit must be used for field wiring. In Europe and elsewhere suitably rated cable is connected directly to the equipment using certified flame proof cable glands.
Advantage – simple to design the system, suitable for high power equipment
Disadvantage – equipment becomes extremely heavy & expensive; opening the enclosure while powered is not permitted
Most of the enclosures will give some protection against the elements. How much protection you need depends on the type of weather you anticipate.
If your enclosure is to be located in an area that is regularly rainy, or has damp weather, anything from IP66 would suit you.
If the weather is simply a little dusty, you could probably use an IP65 enclosure.
Enclosures that are totally waterproof - those that are constantly immersed in water, or immersed for a long period of time carry IP 67 (for temporary immersion in water) or IP 68 (for prolonged immersion in water under pressure)