Data Center Flooring

Generally speaking, the effectiveness of static control flooring properties is based on:

1. A floor’s ability to prevent static in the first place regardless of traffic, humidity or the type of footwear worn by people occupying the space. This ability is called preventing body voltage generation or BVG. This property is measured using test method ANSI/ESD S97.2. The test results should include measurements with and without static control footwear.

2. The intrinsic ability of the floor to be grounded. This is also called finding a traceable “Ground path.” This property is measured using test method ANSI/ESD S7.1-2005. Test results should be obtained on samples that have been preconditioned at humidity levels below 20%. A “highly recommended floor” will usually measure below 1.0 X 10E7 ohms using this test. In the case of anti-static carpet, the test should be performed on new and used carpet to determine if traffic and abuse will degrade the Groundable path.

The following materials have been evaluated for effectiveness in data centers. They appear in descending order of suitability:

Best: Conductive 2 layer ESD grade rubber tile and sheet flooring: Material cost approximately 5-6 dollars per square foot:
Disadvantage: Initial cost

Highly Recommended: Conductive carpet tile: Material cost approximately $3.75-$4.00 per square foot.
Major disadvantages: Allergy considerations, airborne contaminants become trapped in carpet – excess yarn fibers could become lodged in cooling fans.

Recommended but less effective than options 1 and 2: Conductive vinyl: Material cost approximately $3.25-$4.00 per square foot:
Disadvantage: Best when used in conjunction with antistatic footwear.

Marginally effective: Static Dissipative vinyl: Cost: same as conductive vinyl:  
Disadvantage: offers negligible static control performance versus traditional/standard vinyl flooring

Not Recommended: Computer grade floors such as low KV carpet, Dataguard carpet, SDT and High Pressure Laminates (HPL). The anti-static properties of these options quickly degrade after installation and it has been documented in numerous studies that all of these materials become less effective without the regularapplications of special anti static waxes, dissipative polishes and Statguard sprays. These materials are often specified as meeting the outdated IBM Burroughs test.

Although static control vinyl is a significant upgrade over traditional types of flooring, most studies have show that vinyl is less effective than rubber for static mitigation in environments where street shoes are typically worn.

1. Here is a link to a PDF article published by an Emergency 9-1-1 journal about flooring for 911 call centers. This may prove helpful since 911 application criteria for flooring are almost identical to those for data centers.
    
2. Here is a link to an article, originally published in the Data Center Journal about selecting flooring for Data Centers. This is a pdf of the same article.

• Only conductive floors can be grounded. Standard flooring installed with ground strips or conductive adhesive will not offer any static protection.
• Any effective conductive floor can be verified with an ohm meter to determine the electrical resistance of the material. If the material does not pass the ohm meter test than it cannot be grounded.
• Conductive floors should never require any antistatic sprays or waxes to enhance or maintain performance. The conductivity should be achieved by the actual permanent physical composition of the material.
• The floor should reduce static electricity regardless of relative humidity. Ask the supplier specifically about performance in very dry conditions.
• The floor must prevent static buildup in real world conditions without special conductive shoes or shoe straps. When in doubt, ask for independent test data verifying this property. It should be available. The data should come from an installed floor and not from a lab test of new flooring.
• Never assume that a shock-free environment means a static-free environment. A shock-free environment only means that static charges are below 3500 Volts.
• Do the homework up front. It is much more costly to remove an ineffective floor and replace it than it is to do it right the first time. Any mission-critical space is only as secure as its Achilles’ heel.
• Even if your present electronics are immune to static, if at some point in the future they will be upgraded or replaced with state-of- theart equipment, then static will be a problem. As with any potential security breach, it is always best to plan ahead.