15.4.3 Test for non-transmission of an internal ignition
This test shall be made in accordance with 15.2 with the following additions and modifications.
15.4.3.1 Test procedure
An ignition source shall be placed first close to the inner surface of the breathing and draining
device and subsequently in one or more places if a high peak explosion pressure and rate of
rise of pressure at the face of the device is likely to occur. Where the enclosure has more than
one identical device, the device to be tested shall be that which gives the most unfavourable
results. The test mixture within the enclosure shall be ignited. The test shall be made five times
for each position of the ignition source.
15.4.3.2 Non-transmission test for breathing and draining devices
For breathing and draining devices of Groups I, IIA and IIB the non-transmission test of 15.2.1
shall be applied.
For breathing and draining devices of Group IIC with measurable paths, 15.2.2 and either
15.4.3.2.1 or 15.4.3.2.2 shall be applied. For breathing and draining devices of Group IIC with
non-measurable paths, 15.4.3.2.1 or 15.4.3.2.2 shall be applied.
15.4.3.2.1 Method A
For devices intended for use only in hydrogen, only the test with the hydrogen/air mixture is
required. The tests are carried out five times with each test mixture. The tests are made
according to 15.2.2.2 and 15.4.3.1.
15.4.3.2.2 Method B
The use of this method involves limitation of the range of Group IIC gases covered. The
restriction of use shall be indicated accordingly, as specified in 27.2 item e) of IEC 60079-0.
Where exclusion of a specific gas or gases is required, the apparatus shall be marked in
accordance with 27.2 item i) of IEC 60079-0, and specified on the certificate.
Carbon disulphide is excluded for enclosures with a volume greater than 100 cm3.
The test mixtures to be used consist of the following, in volumetric ratio and at atmospheric
pressure:
a) (40 ± 1) % hydrogen, (20 ± 1) % oxygen and the rest nitrogen;
b) (10 ± 1) % acetylene, (24 ± 1) % oxygen and the rest nitrogen.
The tests shall be carried out five times with each test mixture, in accordance with 15.4.3.1.
For devices intended for use only in hydrogen, only test mixture a) is to be used.
15.4.3.3 Acceptance criterion
The test result is considered satisfactory if no ignition is transmitted to the test chamber.