Order of tests for Exd enclosures with non-metallic parts

Order of tests for non-metallic Exd enclosures or enclosures with non-metallic parts

In general, the special tests relevan to Exd enclosures, based on clause 15.1 of EN/IEC 60079-1:2014, shall be carried out in the following order:

a) Determination of the explosion pressure (reference pressure) in accordance with clause 15.2.2 on a specimen which may or may not have been subjected to enclosure tests in accordance with EN/IEC 60079-0.

Note: The general EN/IEC 60079-0 tests are not a prerequisite for carrying out the reference pressure test and can be carried out at any stage of the equipment test list. However, simply because the results of the explosion pressure test are required to be used for the overpressure test, the reference pressure test shall be carried out before the over-pressure test.

b) Overpressure test in accordance with clause 15.2.3 on one of the specimens which have been subjected to enclosure tests in accordance with EN/IEC 60079-0.

Note: Since the results of the reference pressure test must be used to perform the over-pressure test, the over-pressure test must be performed after the reference pressure test.

c) Non-transmission of internal ignition test in accordance with 15.3 on a sample which may or may not have been subjected to the enclosure tests in accordance with EN/IEC 60079-0 or which may or may not have been subjected to the test in (b) above.

Note: The non-transmission of internal ignition test does not have any prerequisites, such as the general tests of EN/IEC 60079-0 or the reference pressure or over-pressure tests, and can be performed at any stage of the equipment testing order.

However, based on the following paragraph of clause 15.1 of EN/IEC 60079-1:2014

For non-metallic enclosures or non-metallic parts of enclosures, the test sequence above is modified by the requirements for non-metallic enclosures and non-metallic parts of enclosures in this standard.

The test sequence for Exd non-metallic enclosures or including non-metallic parts is modified against the sequence defined in the first paragraph of this article, based on clause 19.3 of EN/IEC 60079-1:2014 (requirements for type testing of non-metallic enclosures or including non-metallic parts and their sequence), except for the following items that are excluded by the clause 19.1 of the mentioned standard:
 

• Sealing rings related to cable glands or conduit sealing devices to which clause C.3 of EN/IEC 60079-1:2014 applies;

• cemented joints to which clause 6 of EN/IEC 60079-1:2014 applies; and

• non-metallic parts used in the enclosure on which are not relevant to the type of protection of the enclosure.

Clause 3.19 of EN/IEC 60079-1:2014: Requirements for type testing of non-metallic enclosures or enclosures with non-metallic parts and their performance sequence

1- Determination of the explosion pressure (reference pressure) in accordance with clause 15.2.2 of EN/IEC 60079-1 for a specimen which may or may not have been previously subjected to the tests required for enclosures in accordance with EN/IEC 60079-0;

2- Overpressure test in accordance with clause 15.3.2 of EN/IEC 60079-1 on all specimens which have previously been subjected to the tests required for enclosures in accordance with EN/IEC 60079-0;

3- Non-transmission of internal ignition in accordance with clause 15.3 of EN/IEC 60079-1 on a specimen which has been subjected to the over-pressure test in accordance with the second above point;

The following tests (points 4 and 5) shall only be carried out for enclosures with a volume greater than 50 cm3 whose flameproof joints have at least one sheet of plastic material.

4- Test of erosion by flame in accordance with 19.4 on a specimen which has first been subjected to the non-transmission of internal ignition test in accordance with the third point (above);

5- Test of non-transmission of internal ignition in accordance with 15.3 on a specimen which has first been subjected to the erosion by flame test in accordance with the fourth point (above).