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I NTRODUCT I ON HAZARDOUS LOCATION DATA

Equipment Dust Ignition Protection by Enclosure “t” (‘ta’, ‘tb’, ‘tc’) (removes fuel from the fire triangle.) (Related Standards; IEC/UL/CSA 60079-31) Much like North American dust tight requirements, the objective of the IEC 60079-31 is to prevent dust from entering the enclosure and limiting surface temperatures. All joints must meet IP 6X for Zone 20 and Zone 21, and IP 5X for Zone 22. Unlike UL 1203, there are no minimum joint dimensions that must be met. Non-electrical requirements “h” (removes heat from the fire triangle.) (Related Standards; IEC/UL/CSA 80079 Series) The IEC 80079 Series of Standards address the non electrical methods and types of protection for non electrical equipment. Currently these requirements do not apply in North America. The IEC 80079 Series Standard was based on the (EU) EN 13463 series that was used in the ATEX System. The IEC 80079 identifies Type of Protection (Ex ‘h’). Older ATEX equipment used “c”, “b” and “k”. These symbols are still used internally within ISO 80079-37, but they do not appear in the equipment marking.

activate to prevent an increase in temperature. Flat joints in Dust-Tight equipment can be gasketed and have minimum width requirements. The primary requirement of all joints is to prevent dust from entering an enclosure. Dust layers can build up on equipment which can decrease the heat dissipation generated by the equipment inside. This would increase the surface temperature even under normal operating conditions. The surface temperature tests are conducted with the equipment covered with as much dust as can possibly remain on the equipment. The applicable testing standards for North America are UL 1203 and CSA C22.2 No. 25. While these standards were aligned in 2017, there remains a couple of key differences. UL 1203 has different dust penetration tests than IEC 60079-31 and specific joint dimension requirements. C22.2 No. 25 permits the same dust penetration tests and joint requirements used in IEC 60079-31 as an alternative to those in UL 1203.

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