What are the best practices for data center cleaning?

Avoid contaminants in your data center facility. Create a data center vacuum and cleaning schedule to control what comes in the door.

What's the best way to prevent contamination on the data center floor? Using shoe covers? Wearing pairs of shoes...

only on the data center and anti-contamination mats? Which option is the best? Are there alternatives?

Special shoes and shoe covers are necessary only for true clean rooms. Since we should not be generating any significant contamination within our data center, extreme measures should not be necessary. If the floor slab has been sealed, your ceiling, insulation and/or ceiling slab are non-flaking, your floor is cleaned with a damp mop, the air conditioner filters are changed regularly and you invest in professional data center cleaning once a year, you should limit internally produced contamination rather well. 

The real key to keeping a data center clean: Control what comes in from outside.

Never unpack or uncrate equipment -- and certainly don't store cartons -- inside the data center. You should have a place outside, preferably with a negative pressure environment, where you can unpack and clean all hardware before it comes inside.

Create a "clean zone" outside your data center, such as a vestibule or corridor that is not regularly trafficked and is cleaned daily.

When mechanics or electricians work inside the data center, insist that they wear clean clothing or clean cover-ups. Anything needed from the outside should be brought from the warehouse, unpacked, and handed off at the door. Any server dirt or debris accumulates from work inside the data center and should be cleaned up immediately and preferably simultaneously. Use a commercial vacuum with a HEPA filter next to the work so that loose material can be sucked in immediately. If holes must be bored in the concrete, insist on the use of a hollow, self-cleaning dust removal bit, such as the TE-CD system by Hilti Corp.

Verify that there are no electro-galvanized metals in your air supply or return paths that could grow zinc whiskers: tiny metal particles that can form, break off and be carried into your equipment circuitry. Check raised floor panels and cable trays especially. Request written certification from manufacturers that products in your data center are tested and will not grow zinc whiskers in air plenum spaces.

Have a professional check your outside air supply. Code requires that a certain amount of fresh air be brought into a building, but the air should be well-filtered before it gets into your data center facility. Weather, seasons and activities such as nearby construction affect air quality. Take additional filtering steps to remove any gaseous pollutants present, particularly if they contain sulfur or hydrocarbon compounds that can become acids in the presence of humidity, corroding circuit board lands and connectors. This should not be a serious problem in the United States or most of Europe, but there are places in the world where it's a significant concern. Be wary if a manufacturing plant nearby deals with harsh chemicals.

The key to keeping airborne contaminants out of the data center is to avoid bringing them in. But since you can't stop everything without creating an impractical operating environment, do the next best thing -- employ a specialized data center cleaning service as part of your yearly maintenance plan.

For more detailed information and a better understanding of the problems with contaminants in data centers, go to the ASHRAE TC 9.9 Website and look up the book Particulate and Gaseous Contamination in Datacom Environments.  

About the author:
Robert McFarlane is a principal in charge of data center design at Shen Milsom and Wilke LLC, with more than 35 years of experience. An expert in data center power and cooling, he helped pioneer building cable design and is a corresponding member of ASHRAE TC9.9. McFarlane also teaches at Marist College's Institute for Data Center Professionals.

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