Aspects regarding the influence of internal explosions over the maximum surface temperature for equipment with type of protection flameproof enclosure

Abstract

The type of protection flameproof enclosure “d” consists in placing the parts that could ignite an explosive atmosphere inside of an enclosure that can withstand the pressure developed during an internal explosion of an explosive mixture and which prevents the explosion transmission to the explosive atmosphere surrounding the enclosure. The protection to explosion must remain valid even in case of an internal explosion. The maximum surface temperature of electrical equipment is defined as the highest temperature which is attained in service under the most adverse conditions (but within the specified tolerances) by any part or surface of equipment. When determining the maximum surface temperature of a flameproof equipment the temperature of external surfaces is considered. The increase of temperature due to an internal explosion is not considered. The purpose of this paper is to highlight this temperature increase during an internal explosion in case of a flameproof enclosure.