The Design and Application of Flameproof Lighting Equipment

Abstract

In industries where there are explosive or inflammable hazards, it is required that the lighting system should preclude the possibility of explosion or fire as a result of accidental sparking or damage to the equipment.

Explosion hazards may be divided into two main groups:—

• (i)

Hazards in buildings or parts thereof where gases, vapours or volatile liquids are present and may form an explosive mixture with air, either at room temperature or at some higher temperature;

(ii)

Hazards where dusts may be in an explosive mixture with air.

In general, one of two systems of lighting may be employed where an explosive or inflammable hazard exists:—

• (i)

By an external lighting system whereby the light sources are placed outside the building and arranged to project light through “windows”;

(ii)

By an internal lighting system:—

• (a)

In which flameproof lighting equipment must be employed throughout owing to the nature and extent of the hazard, or

(b)

In which flameproof equipment is required only for specific areas where a “local” hazard may exist, e.g., in paint spraying booths.

This paper relates solely to flameproof lighting equipment for use in hazardous situations, and docs not include reference to external lighting systems or to the installation of heavy-duty dustproof fittings which may be acceptable for some locations where certain dusts may be in an explosive mixture with air. Furthermore, the paper is concerned primarily with features of mechanical design, although reference is made to the factors which influence the lighting result.