doi:10.3850/978-981-08-7724-8_13-06

ABSTRACT

In flameproof electrical apparatus for explosive gas atmospheres any holes and gaps in the enclosure wall have to be designed in such a way that a gas explosion inside the enclosure will not be transmitted to an explosive gas atmosphere on the outside. In current international flameproof-apparatus standards high demands are made on the smoothness of the surfaces of such holes and gaps. In the present investigation these requirements are challenged. In a series of controlled experiments with a plane-flange carbon-steel flame gap, the influence of mechanical roughening of the gap surfaces by sandblasting and corrosion (rust), on the ability of the gap to prevent explosion transmission, has been studied. The results showed that neither sandblasting nor rusting had any significant effect on the gap efficiency. This may suggest that flame gap surfaces in flameproof electrical apparatuses can suffer considerable mechanical and corrosive damage before the gaps do no longer function satisfactorily.

Keywords: Gas explosions, Electrical equipment, Flameproof gaps, Surface roughness.

© 2011 CPD Unit, University of Leeds