Contamination affecting ICT comes in two forms particulate matter (PM) and gaseous. These cause problems for many reasons. If PM blocks equipment cooling fans and heatsinks, they must work harder to keep equipment within operating temperature limits. This can increase a data centre’s power demand by 2% or more, as well as potentially shortening equipment lifetime and causing hardware failure due to overheating. Zinc whiskers and other PM can bridge between conductive tracks within electronics equipment, causing short circuits and hardware failures a growing occurrence as ICT equipment shrinks in physical size, correspondingly reducing track bridging distances. Fibres longer than 5 mm have been found inside data equipment. Oxidisation arising from gas interaction can cause permanent corrosion, leading to irreparable equipment damage and failure.
External sources include cars, electricity generation, sea salt, natural and artificial fibres, plant pollens and wind-blown dust. Internal examples are particles from air conditioning unit fanbelt wear, toner dust, packaging and construction materials, human hair and clothing, and zinc whiskers from electroplated steel floor plates. Contaminating gases occur naturally or result from industrial processes. They can either act alone or together with other gases or PM, forming compounds that oxidize metallic materials.
Contaminants enter the data centre through air conditioning units, open doors, on clothes and anything else brought into the room. Activities such as equipment maintenance or lifting floor or ceiling tiles can also release PM which can then reach ICT equipment through gravity, diffusion or electrostatic attraction.
Contamination prevention starts with the design of the data centre and surrounding areas. Relevant factors include using air handling unit filters, positive pressurization, limiting the number of room entrances, using Takmats to capture footwear and trolley wheel dirt, subfloor area sealing and using suitable materials and fabrics within the data area. A policy for controlling and limiting visitors into the data area is also important.
Decontamination cleaning success depends on the frequency as well as the nature of the cleaning activities. Ideally, these should start before the first item of ICT or even associated hardware such as cable trays or suspended floors are installed. This is because cleaning areas consigned to such installations becomes more difficult or impossible once they are in place. And, clearly sensitive ICT equipment once installed will benefit from starting life in a clean environment. For example a “Post Construction Clinical Clean” includes cleaning of the subfloor void, floor surface, equipment surfaces and the pedestal and stringer substructure to ensure that the data centre is ready following any building work. After the data centre’s operational life starts, any cleaning schedule should allow for maintenance activities, which increase contamination levels.
In any case planning an effective cleaning program, in which both the schedule and nature of the cleaning activities are optimised, requires specialist knowledge of how locally prevailing conditions contribute to contamination problems, and how to prevent this. Therefore, working with a specialist data centre cleaning company is essential. Using a general cleaning contractor or DIY may seem cheaper in the short term, but a critical lack of knowledge could cause serious downtime problems later.
A specialist cleaning contractor should work to ISO 14644, the globally accepted standard for contamination management in clean rooms including data centres. This Standard defines Cleanliness Classes from Class 9 to Class 1, specifying maximum allowable concentrations of particles from 0.1 to 5 ?m. The lower the Class number, the more stringent are the concentration limits. Specialists recommend Class 9 to Class 6 cleanliness for data centres. After cleaning, a particle counting meter can measure and prove the level of cleanliness achieved. This not only assures the data room operator of his security from contamination, but also provides hard proof and certification that the room is clean to a universally accepted standard; essential as ICT vendors increasingly use insufficient contamination protection as a reason to void equipment warranties.
Particle sampling provides valid proof of room cleanliness at the time of measurement, but it doesn’t allow for any settled PM, or of contaminant later introduced into the area. An onsite risk assessment can reveal contamination sources, allow for nearby installations that could impact contamination levels, and check air filtration procedures. Access policies for people and materials can also be reviewed. This information will contribute to a cleaning strategy cost-effectively matched to facility needs. Sustained protection of on-site equipment from contamination induced failures will be secured. The facility’s carbon footprint will also be reduced as unobstructed equipment cooling fans run more efficiently.
A specialist data centre cleaning contractor will always use permanent staff rather than subcontractors.