15.1 Tests of ability of the enclosure to withstand pressure
15.1.1 General
The object of these tests is to verify that the enclosure can withstand the pressure of an
internal explosion.
The enclosure shall be subjected to tests in accordance with 15.1.2 and 15.1.3.
The tests are considered satisfactory if the enclosure suffers no permanent deformation or
damage, affecting the type of protection. In addition, the joints shall in no place have been
permanently enlarged.
15.1.2 Determination of explosion pressure (reference pressure)
The reference pressure is the highest value of the maximum smoothed pressure, relative to
atmospheric pressure, observed during these tests. For smoothing, a low-pass filter with a
3 dB point of 5 kHz ± 10 % shall be used.
For electrical apparatus intended for use at an ambient temperature below –20 °C, the
reference pressure shall be determined at a temperature not higher than the minimum ambient
temperature.
As an alternative, for electrical apparatus