Lighting Design + Application • October 2003 - Illuminating ...

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .DESIGN TRENDSAll clean room surfaces must successfully stand-up torigorous cleaning protocols, which is why stainless steelis specified for everything from test tanks to luminaire housings.There are a number of different clean room scenarios,most of which relate either to research or productionactivities. Within these two areas the primary types ofclean rooms are those that keep contaminants out (positivepressure environments) and those that keep organismsand chemicals in (negative pressure environments).The biopharmaceutical industry has developed a majorpresence (on the West Coast in particular) during the pastdecade, creating an increasing demand for clean rooms,while a large number of pharmaceutical companies on theEast Coast have become involved in research requiringfacilities with cleanliness and containment properties similarto those of the West Coast biopharmaceutical industry.But, whether a facility is concerned with keeping contaminantsout or chemicals or organisms in, the lighting challengesare similar.Lighting ChallengesDesigning and specifying appropriate and effective lightingin clean rooms can be highly problematic in four basicareas:• Lack of Available Ceiling Space. Clean room ceilingsare typically dense with mechanical systems andcomponents. So dense, in fact, that reflected ceiling planscan look like circuit board schematics. The most noticeableand numerous mechanical elements are the HighEfficiency Particulate Air (HEPA) filters that filter-out particulatematter. The quantity of these filters is dependenton the type of work being performed and the amount ofparticulate matter allowable within the space. BesidesHEPA filters, there are also sprinklers, ducts and the othermechanical systems necessary to satisfy life safetyrequirements and support the work function. The densityof ceiling-mounted mechanical hardware is often so greatthat there’s inadequate ceiling area available for appropriateluminaires or effective lighting layouts.• High-Impact Cleaning Protocols. An integral partof maintaining a clean environment is the regular washingof all room surfaces and equipment with high-strength solventsand detergents. In addition to the often abrasive, corrosiveor otherwise destructive properties of the cleaningsolutions themselves, protocols can result in considerableforce in the wet swabbing process to ensure compliancewith cleanliness standards. As a result, most materialsused in clean environments must be specified with unusuallyharsh cleaning processes in mind. There are also applicationswhere chemicals are either used in open conditions(such as in open mixing bowls), or where chemicalscan be accidentally released into the environment, exposingroom materials to their potentially damaging effects aswell.• Luminaires as Contaminant Barriers. As mentionedearlier, clean rooms must be sealed either to keepcontaminants out or to keep chemical or biological matterin. Accordingly, fixtures that penetrate ceilings must alsofunction as barriers, preventing leakage both through theirown components and via their ceiling interface. Thismeans that a fixture’s internal mechanical tolerances mustClean room ceilings can be so dense with filters and other mechanicalsystems that drawings often look more like circuit boardschematics than reflected ceiling plans.. . . . . . . . . . . . . . . . . . . . . . . www.iesna.org . . . . . . . . 63. . LD+A . . . November . . . . . 2003 . . . . . . . . . . . . . . . . . . . . .