Lighting fitting

DETAILED DESCRIPTION We claim: 1.
A light fitting comprising a ballast casing enclosing first means for communicating with a source of electrical current, a large shade provided with a reflector, second means connecting the ballast casing with the lamp shade, a bulb holder and a bulb mounted on said bulb holder, said bulb holder being located on said second means, third means defining a chamber surrounding said bulb, the ballast casing having a cover and defining together with said cover a cavity, a filter connected with said cover, said filter being placed away from said bulb whereby it is not substantially heated by the heat generated by the bulb when the light is on, fourth means for communicating said bulb chamber with the cavity defined by said ballast casing and said cover, an orifice in said filter located opposite said cover, said orifice providing for the flow of air from the bulb chamber to the surrounding when the light is on and when the air in the bulb chamber is under increased pressure and providing for the flow of air from the surrounding into the bulb chamber when the light is turned off and the pressure in the interior of the bulb chamber becomes lower than the pressure in the surrounding, said filter comprising filter elements retaining dust, smoke and vapor and activated carbon as a filter element adsorbing gases, said filter being connected to said cover by means of a threaded joint, the filter being a casing of large diameter as compared with the size of the threaded joint.




Description:
FIELD OF THE INVENTION The present invention relates to a lighting fitting of a closed construction, especially meant for use in an industrial environment containing dust, smoke, gas, and vapor.
DESCRIPTION OF THE PRIOR ART A lighting fitting used in an industrial environment in time gets soiled, which results, among other things, in poorer lighting efficiency.
A lighting fitting gets soiled both on the outside and on the inside.
The outer surface of the glass of a lighting fitting is relatively easy to clean, but cleaning its inner surface, the reflector surface and the bulb is more problematic