Explosive atmosphere ignition source identification during mining plant suspended monorail braking unit operation

causes of mining disasters in hard coal mines all over the world, and
research continues to be conducted with the purpose of
understanding the mechanisms of an explosion, explosion
prevention and risk reduction. This article presents the test
methodology as well as virtual and bench test results for a braking
unit, which constitutes one of the main components of a suspended
monorail transport system. The design work and virtual and bench
testing were performed as part of a European research programme.
The tests were conducted in a dedicated specialist test facility. The
tests were based on Polish standard PN-G-46860:2011, concerning
braking trolleys employed in mining plant suspended railway
systems. The tests also factored in the requirements for nonelectrical devices intended for use in explosive atmospheres,
including braking systems, as defined in standard PN-EN ISO
80079-36:2016, harmonised with the ATEX directive. The test
scope encompassed braking unit operational component
temperature measurements using thermal imaging and the contact
method, as well as braking distance measurements. Further tests
involved virtual simulations of brake pad heating. The tests
employed the finite element method (time-varying calculations).
Results obtained over the course of numerical calculations indicate
that brief brake pad friction face heating, even up to a temperature
exceeding 200°C, does not result in inward heat propagation
towards the brake pad material. This is also confirmed by the
measurement results. However, under real conditions, the braking
unit would be engaged only during an emergency situation, which
would not lead to exceeding the permissible brake shoe material
temperature values.