LED light­ing in haz­ardous en­vi­ron­ments

DEMM Engineering & Manufacturing - - ELECTRICAL TECHNOLOGY -

LED Light­ing has been around for a while now, and in the Industrial and Com­mer­cial space the change has been dra­matic. The de­sire for longer life lamps fu­elled the orig­i­nal drive to LEDs, but there have been many more ad­van­tages that came as part of the pack­age.

In haz­ardous en­vi­ron­ments (flammable ar­eas) the move to LEDs has been slower and more mea­sured. There are so many boxes to be ticked be­fore a tech­nol­ogy can be used in a po­ten­tially flammable en­vi­ron­ment that man­u­fac­tur­ers can­not make a change like this lightly. The cost of the ap­proval process alone would bring tears to the av­er­age ac­coun­tant’s eye.

The main chal­lenge for man­u­fac­tur­ers has been deal­ing with the heat gen­er­ated by the elec­tron­ics driv­ing the lamps. Some man­u­fac­tur­ers rushed in and then dis­cov­ered the life­span was no bet­ter than be­fore. This was mainly due to elec­tronic fail­ures, of­ten at­trib­uted to the en­closed fit­tings not be­ing able to dis­si­pate a suit­able amount of the heat. Their chal­lenge was that a Haz­ardous Area fit­ting must have a de­signed in, max­i­mum sur­face tem­per­a­ture. The more LEDs the more power re­quired to drive them and the more heat gen­er­ated.

As each gas, vapour or dust has a tem­per­a­ture that it will au­to­mat­i­cally ig­nite, it is im­por­tant to keep that heat be­low those tem­per­a­tures, and there­fore keep the en­vi­ron­ment safe. High power LED tech­nol­ogy is still a work in progress and mul­ti­ple LEDs are needed to cre­ate enough light. This has meant some LED fit­tings are larger than the pre­vi­ous light source mod­els, as sur­face area is the only cost ef­fec­tive method to dis­si­pate the heat.

Some man­u­fac­tur­ers that have re­cently en­tered this chal­leng­ing field have opted for later tech­nolo­gies, with smarter elec­tron­ics, to max­imise the light out­put in a smaller and more ef­fi­cient fit­ting. If the plant has ex­ist­ing flu­o­res­cent fit­tings, re­plac­ing th­ese di­rectly with LEDs has ad­van­tages. A re­place­ment can be made within the same mount­ing foot­print and use the same brack­ets if the right model is cho­sen. If this LED fit­ting also meets all of the ex­plo­sion pro­tec­tion char­ac­ter­is­tics of the flu­o­res­cent it can be used in the same flammable at­mos­phere with­out any degra­da­tion in safety.

LEDs also al­low for in­no­va­tion from the light­ing man­u­fac­turer. Tubu­lar fit­tings of dif­fer­ent lengths for ap­pli­ca­tions where tra­di­tional fit­tings have not pre­vi­ously fit­ted are mak­ing the Haz­ardous area less of a chal­lenge to light than ever be­fore. LED work lights for con­fined spa­ces are a huge as­set. No more bump­ing the lamp and hav­ing the light go out just as you got to the work space. Ad­di­tional volt­ages for a larger range of ap­pli­ca­tions are now avail­able.

The other ad­van­tage of LEDs is en­ergy sav­ing. The lu­mens or lux (some have pref­er­ences) out­put per watt of en­ergy is sig­nif­i­cantly re­duced. In one case to achieve the typ­i­cal light out­put of a 2 x 58W flu­o­res­cent fit­ting only re­quires a fit­ting the length of a tra­di­tional 2 x 36W, and uses less en­ergy. This will see sig­nif­i­cantly less space re­quired for light­ing over time and def­i­nite re­duc­tions in en­ergy bills. The one down side can be the in­tense light from the fit­ting. Choos­ing a fit­ting with an op­ti­cally cor­rect dif­fuser with LEDs is im­por­tant to re­duce glare.

There is no doubt that LEDs are the flavour of the month in flammable en­vi­ron­ments. Be care­ful to check the “T” rat­ing. That’s the max­i­mum sur­face tem­per­a­ture that the fit­ting will at­tain un­der a nor­mal am­bi­ent tem­per­a­ture. Check for dif­fusers; are they avail­able? LEDs with­out dif­fusers could be a haz­ard in them­selves. Each LED is very bright. Check for en­ergy sav­ing and lux out­put. They should be sig­nif­i­cantly bet­ter than a stan­dard fit­ting.

The bonus: Ex­tremely long lamp life and peace of mind. Sup­plied by Mike Barker, Mar­ket Manager Con­trol & De­fence, Elec­tropar PLP

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