LPG

IP is for 'Ingress Protection', it is not for the explosion proof designation. IP designation of an enclosure is the degree of the protection from the intrusion of the environmental solid objects and liquids into the enclosure (see http://www.neteon.net/RefDnFiles/IP%20Rating%20Reference.pdf for details). IP54 should be enough protection in this case. I worked in a refinery in the heavy rain fall and dusty area. We used IP54 for outdoor equipment and had never problem.

The explosion proof equipment protects the out side explosive environment from the inside explosion of the equipment. All electrical equipment that is used in the hazardous area (Zone 0, 1 or 2) must be explosion proof. In the case of propane, the equipment designated as EEx d IIB T4 (IIB for gas group for Ethylene and temperature code T4 for 135 degree C) should be enough, however consult an expert before select the equipment. For propane, you even can select lower grade of explosion proof such as EEx d IIA T1 (IIA for gas group for propane and temperature code T1 for 350 degree C). The gas group indicates that the internal explosion can occur with the type of gas indicated and the temperature code indicates that the equipment surface temperature will never goes beyond the indicated temperature when the external explosion occurs. The 'T' code should be selected in such a way so that the flash point of the gas is higher than the temperature of T code. The selection, especially the letter 'd', also depends on the equipment you are selecting – it could be also i or e instead of d.

All these above are per IEC (European) standards. If you are in North America, then the designations are different. You have to select the equipment per the NEMA enclosure protection and NEC 500 explosion classification.

- MS