Document npD2jL1BoJ44XrExq4N112YG6

778 S. K. GUTH AND.E. A. LINSDAY well-designed fluorescent system may be obtained at little additional cost,58 an<| in many cases the total cost per footcandle of illumination is lower than with filament system. TM A. MAINTENANCE A good lighting system requires a good maintenance program, which include]! periodic cleaning57 of lamps and fixtures, repainting of room surfaces, and replacj| ing burned-out lamps. ' jit Dirt and dust accumulation on lamps and fixtures58 can reduce light output! by as much as 50 per cent (Figure 26). Not only is the generated'light that is niff fe-V gp Mi: y%;. &lp LIGHTING FOR SEEING 779 m. Figure 26. The effect of ventilation on dirt accumulation on reflector surfaces. Dust|aS dirt settle onto the reflector (left) when no ventilating holes or slots are presents Holes? the top of the. reflector (center) provide an exit for the dust laden air, warihed by the lamSc pass through.J?ortio'n of reflector below the holes is thus kept cleaner. Holes placed in th'e|l (right) provide this same chimney effect keeping the entire reflector surface cleaner. M being utilized expensive, but also the loss in illumination may' result in Ic||| production and an increased accident rate. For servicing high mounting instH^ tions in large areas it is sometimes economical to provide built-in catwalks* movable platforms suspended on a cable (Figure 27) .or the crane railsiW^ fixturesiih'fffcSfe^m'ounted'rlowerrtsca'ffoldsr-movAbler-pla'tforihs-r-bfafQrlpitFiiGf^ the usual possible, all cleaning equipment, tanks, and-'YepiScement lamps should be within easy reach of the imainttnanciV man to conserveltime and cost of cleaning and relamping. In the average' incu-.i'nlfli .. _ ___ "'AT'erBmT-aniF^Er-A-mrckpFundamentsls-o'f-lighting-Gost-anAlysig^S'fflEwnra ~ **" 260 <"19L5i2g)h' ting maintenance--cleaning, Bulletin LS-166, Lamp Division, General Electric Decem"bCe.r,E1.9E54g.eler and R. F. VandenBoom, Maintenance of industrial lighting, Illum.^Eng 46, 522 (1951). si! ^ figure 27. Mymjenance^of-nuo/e^fc^ a system 'to^of^amtenance.caggs impended\Ironi`cabl^s.^Cage, including maintenance . man .and cleaning ' ,aipmenti can easily be pulled'forward or back by the operator. B ' r:-'v" ' , . \- ol B* l-0-so VJ?'*** - ' 40| w*. w! MONTHS OF SERVICE 20 fiSWKj [^Figure 28. Light-output depreciation due to luminaire dirt only, in heavy industry. P and Pffi.vn pfesent porcelain enamel and synthetic enamel fixtures, respectively. Wattage of fluorescent' gjQjmps used is indicated by the numbers. v ,\ 1 ' ?l j' `"1