IEC 60079-31:2008/ISH1:2022

IEC 60079-31:2008/ISH1:2022 – 1 –

© IEC 2022


INTERNATIONAL ELECTROTECHNICAL COMMISSION


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IEC 60079-31
Edition 1.0  2008-11





EXPLOSIVE ATMOSPHERES –


Part 31: Equipment dust ignition protection by enclosure "t"


INTERPRETATION SHEET 1



This interpretation sheet has been prepared by IEC technical committee 31: Equipment for
explosive atmospheres.
The text of this interpretation sheet is based on the following documents:
DISH Report on voting
31/1605/DISH 31/1616/RVDISH

Full information on the voting for the approval of this interpretation sheet can be found in the
report on voting indicated in the above table.

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IEC 60079-31:2008 Edition 1.0, Explosive atmospheres – Part 31: Equipment dust ignition
protection by enclosure "t"

Question 1:
The requirements given in 5.2.2 of IEC 60079-31:2008 (Edition 1) permit threaded entries for
dust protected enclosures to be tapered threads or parallel threads with not less than five
threads, with a minimum tolerance of medium or fine according to ISO 956-1 and ISO 965-3.
Does the description of threads include other thread forms such as ISO 228-1 threads (these
threads are commonly referred to as BSPP or Type G threads and BSPT or Type R threads)?
Answer 1:
No, only metric and NPT threaded entries are permitted for enclosures having equipment dust
ignition protection by enclosure.
NOTE It has been determined that some sizes of Type G and NPT threads will engage but will result in a mismatched
thread engagement. The intention of the restriction to only metric and NPT
...