Static Electricity Professionals

Mission Critical Anti Static Flooring for Public Safety Emergency Communications Applications: Which Resistance Range is Correct – Static Dissipative or Conductive?

 Understanding Grounding Standards: Motorola R56 and ATIS-0600321-2010

Unnecessary confusion exists over which ohms resistance rating is correct for grounded static control flooring used in end user operational equipment environments. The root cause of this confusion is the misapplication of flooring requirements used in electronics manufacturing and explosives handling with the recommendations of compliance/standards organizations overseeing telecommunications and data center environments. The purpose of this post is to clear up this confusion by providing information and links to appropriate industry resources and standards organizations. (Please note: ESDA document ANSI/ESD S20.20-2007 is not referenced.  S20.20 is intended for program managers involved with the design and implementation of a static control process in ESD protected areas as part of a comprehensive program in electronics manufacturing environments.) This article focuses on non-factory, end user operational equipment concerns like networked offices, data centers and emergency dispatch call centers.

  During research for an article to be published by The Construction Specifier in their September issue, we examined FAA, telecommunications and computer industry grounding, lightning, electrical surge and safety standards. The research yielded information that lays to rest outdated assumptions about the proper electrical specifications of floors – particularly carpeting - installed in environments where static sensitive operational equipment is used. Many ESD flooring distributors incorrectly assumed that conductive flooring measuring between 2.5 X 10 E4 and 1.0 X 10 E6 was acceptable for end user environments. This static prevention strategy was borrowed from unrelated requirements involving the mandatory use of conductive flooring when handling explosives and flammable materials. This assumption and the applicability of explosives grade flooring for installation in end user environments – spaces often accessible to the public - is incorrect and poses unnecessary risks. Conductive flooring does not comply with the pertinent grounding standards for telecommunication equipment end user spaces. According to five different authorities/standards organizations, there is consensus in the recommended ohms resistance range for the type of flooring discussed here. The overlap or consensus opinion consists of a recommended ohms range above 1.0 X 10 E6 and below 1.0 X 10 E9 for end user spaces like server rooms, 911 call centers and data centers.

Specifically we looked at standards and recommendations from the following organizations:

 Link to IBM site recommendation and physical planning

IBM's Recommended range of flooring 1.5 X 10 E5 – 1.0 X 10 E10 ohms

A common document referenced by data center designers

 

Motorola R56: The Motorola guidelines have become the recognized standard in the industry and serve as the most complete and rigorous specification for the protection of communication system equipment installed at public safety and commercial wireless communication sites

Link to Motorola R56 See pages 468-470

Excerpt from Appendix C 3.3 of 2005 - 68P81089E50-B
9/1/05 — UP Version:

"Carpeting or floor tiles within an equipment room or dispatch center, including raised flooring, should have a resistance to ground measurement of between 106 and 109 ohms when measured using the test method of ANSI/ESD STM7.1-2001 or later"

 A new revision will be coming soon. This information was provided directly to Staticworx by the current working R56 committee.The excerpt from the new version is pasted into the bottom of this post

This standard should be cited when defining grounding parameters in public safety 911 communication centers

 

Alliance for Telecommunications Industry Solutions (ATIS) ATIS-0600321-2010

ATIS publishes standards for the information, entertainment and communications industries 

Electrical Protection for Network Operator-Type Equipment Positions

Link to ATIS-0600321-2010  Protection for Network Operator-Type Equipment Positions

Available for purchase: Digital Edition available from www.engineers.ihs.com

 Excerpt: Page 5, Section 4.2 Flooring

"Any carpeting or floor tiles should have a resistance to ground between 10 E6 and 10 E10 ohms when measured using the method of ESD-S7.1."

A telecommunications standard overseen by most telecommunications manufacturers

Applicable to numerous environments

 

Link to FAA STD 019e Lightning and Surge Protection, Grounding, Bonding and Shielding

Section 4.1.3.4.3.5 Static Dissipative ESD Floor Coverings

Recommended range of flooring 1.0 X 10 E6 – 1.0 X 10 E9 ohms

The 019e document supersedes a previous document (019d) where conductive flooring was considered acceptable.

 

Requirements for the Design of ICT Rooms - Best Practice Document

European Requirement

Recommended range of flooring 1.0 X 10 E6 – 1.0 X 10 E7 ohms per a European resistive properties test method.

Section 3 – Subsection 9 General Requirements

 

As you review these organization’s recommended parameters keep in mind 3 factors:

1.   Research has shown that conductive flooring offers no advantage over static dissipative flooring in end user environments.  

2.   When evaluating the ohms ratings, keep in mind that the difference between each ascending exponent is a factor of 10.  For example 1.5 X 10 to the 4^th = 15,000 ohms --- 1.5 X 10 to the 5^th = 150,000 ohms

3. A floor measuring between 2.5 X 10 E4 and 1.0 x 10 E6 is defined as a conductive floor. A floor measuring between 1.0 X 10 E6 and 1.0 X 10 E9 is defined as a static dissipative floor.

 Addendum: As part of our research we contacted a member of the Motorola committee overseeing Motorola R56. The purpose of contact was to determine if Motorola might be expanding their electrical resistance range for acceptable static control carpet. The published range since 2005 has been 1.0 X 10 E6 to 1.0 X 10 E9 ohms. There is currently a new draft of R56 in the works. As with other grounding and electrical standards organizations like ATIS and FAA 019e, we were told that Motorola’s acceptable resistance range will remain in the static dissipative range from 1.0 X 10 E6 to 1.0 X 10 E9.

Below is an excerpt of the flooring section as it will appear in the new draft:

Motorola R56 Appendix C

PROTECTING AGAINST ELECTROSTATIC DISCHARGE (ESD) IN EQUIPMENT ROOMS AND DISPATCH CENTERS

C.3.3 FLOORING

Carpeting or floor tiles within an equipment room or dispatch center, including raised flooring, should have a resistance to ground measurement of between 106 and 109 ohms when measured using the test method of ANSI/ESD-S7.1-2005 or later. Existing flooring that does not meet this requirement should be treated with a topical solution such as an antistatic floor wax or spray solution. The effectiveness of antistatic solutions is temporary and varies with floor material and relative humidity. Flooring resistance should be monitored every two weeks minimum to verify conformance to the above requirements. See ATIS-0600321.2010, section 4.2 and ANSI/ESD-S7.1-2005 for more information.

When ESD protective flooring is used, the following should be observed:

• ESD protective flooring shall be installed per the manufacturer's recommendations.

• ESD protective flooring and floor coverings should be installed, grounded, and tested by trained installers.

• Personnel entering the equipment room or dispatch area should wear ESD dissipative footwear or dissipative foot straps. The footwear should provide dissipative resistance values of less than 3.5 ´ 107 ohms as measured according to the measuring requirements within ANSI/ESD STM97.1-2006 or later. The footwear should also provide dissipative resistance values of less than 1.0 ´ 109 ohms as measured according to the measuring requirements of ANSI/ESD STM97.1-2006 or later.

 When ESD protective flooring is not installed at a dispatch position or equipment room, an ESD protective floor mat should be installed at the work areas. When ESD protective floor mats are installed, the following should be observed:

• The floor mat should provide dissipative resistance values between 106 and 109 ohms when measured using the test method of ANSI/ESD-S7.1-2005 or later.

 

Next blog:

We will investigate the grounding parameters required by medical electronic manufacturers for end user clinical environments.

 

How to discuss and recommend the right static control flooring with a client

A guide for architects working within client environments and applications that require conductive flooring

I recently visited with an architect who asked me how to best discuss and guide a client interested in using static control carpet in their application and environment.

There are two main question areas to begin the client discussion and help determine the right static control flooring recommendation:

1. What is the electronic industry supplier environment? Are they actively handling static sensitive electronic parts and sub-assemblies (as opposed to using them)?
   
2. What is the end user environment? Is the organization reliant on electronic systems that may be affected by static discharge events?

Specifying for electronic industry supplier environments handling static sensitive electronic parts and sub-assemblies

Electronic industry supplier environment organizations make, handle, test, store and repair electronic parts. A static event in these types of spaces would damage or destroy the part, assembly or final system. Grounding is achieved by wearing conductive heel straps or special shoes in conjunction with a grounded static control floor. In other words, personnel need to be grounded in any operation in this environment.

Generally, organizations handling and producing static sensitive parts designate certain areas as “ESD safe areas” or static free zones; an ESD safe area requires vigilant compliance with personnel grounding procedures as well as numerous other protocols for preventing the generation and accumulation of static electricity. The processes in these environments are usually governed by international standards like ANSI/ESD S20.20-2007.

Best flooring solutions for electronic industry supplier environments

Staticworx works with the architect to help narrow down which flooring to specify for the client for this type of application:

• EC ESD Rubber
• ESD Carpet Tile
  (not the same as low kV or computer grade carpet)
• ESD Vinyl Tile
  (Also called static conductive and static dissipative tile)
• Conductive Epoxy Coatings

For more information on conductive flooring solutions for electronic industry supplier environments, read the article, “Taking the Mystery Out of Selecting ESD Flooring” which is part of the Staticworx Knowledge Center.

Specifying for electronic industry end user environments: operations reliant upon electronic systems

The term “reliant upon electronic systems” means that the operation does not involve active handling, testing or assembly of electronic sub assemblies. These operations are electronic systems end user environments requiring sophisticated electronic equipment to accomplish their mission.

These spaces are often called Mission Critical Environments: examples include data centers, R & D labs, 9-1-1 call centers, hospital ERs, MRI suites, communication centers, flight towers, control rooms. These spaces utilize operational electronic systems which are manned by personnel who will not use special footwear. A static problem in these spaces would lead to an event that would impact either the equipment, operational mission or both. Examples of these types of problems include: data corruption, system lock-up, dropped phone call, unintended signals in a system.

In these applications, the static control floor must be fault tolerant. (See my recent blog entry on fault tolerant design.) The flooring must prevent the generation of static without the added benefit of special footwear; conversely the anti static floor must prevent static despite the use of static generating footwear.

Best flooring solutions for electronic industry end user environments

Most static control flooring will not inhibit static without the use of special footwear. That said, there are two flooring materials that perform very well despite this obvious deficiency and that Staticworx recommends for electronic industry user environment applications:

• EC ESD Rubber
  (with carbon chip conductors)
• ESD Carpet Tile
  (with conductive fibers wrapped around nylon tuftsand conductive backing.
  Not the same as low kV or computer grade carpet)

For more information on conductive flooring solutions for electronic industry end user environments, read these articles, part of the Staticworx Knowledge Center:

• Static Control in a 9-1-1 Call Center: City of Lowell Case History
• Static Control Flooring for Data Centers (featured in The Data Center Journal)

How to Ground SD Monolithic Seamless Epoxy Coating Floor

Client Question
We are considering applying Staticworx Groundworx ESD epoxy paint over two surfaces in our building. The areas are either sealed concrete or covered with regular VCT. Will the Groundworx floor meet ESD standards even though it will be installed on top of non-ESD flooring? - Keith, Texas

Answer
My company's Staticworx Groundworx Epoxy is produced using graphite particles. These particles create a conductive matrix within the liquid. When applied over any surface, insulative or otherwise, the Groundworx cures into a homogeneous ground plane in all directions. Continuity is achieved across all points of Groundworx regardless of the electrical properties of the surface underneath it.

However, the “Groundworx ground plane” still needs to be grounded once every 1000 square feet using our copper ground strips. The strips are 2 inches by 24 inches in length. They can be attached to the floor using glue or double-sided tape. Part of the strip touches the floor and the other end of the strip should attach to an electrical box, a piece of conduit, building steel or a metal stud that is in continuity with the AC or building ground. (See article: Best Way to Ground ESD or Static Dissipative Flooring) When applying the Groundworx, make sure you coat over the portion of the copper strip touching the floor. This is the only necessary step for grounding a Groundworx floor.

Learn more about Staticworx Groundworx Epoxy
Read this article on the Staticworx website, in the Knowledge Center Area

Are You Grounded? Evaluating Waxed, Solid Dissipative Vinyl Tile vs. Wax-Free, ESD, Conductive Vinyl Tile

Recently we decided to do some spot testing of various “conductive” flooring products in our office in Massachusetts as an exercise to further develop our library of resources available to those who struggle to understand ESD flooring and the underlying principles of static electricity. It is important to note that the day we tested it was very cold outside (and in our office) and that the low relative humidity is the main reason for choosing this particular day to conduct these tests. Static problems are more prevalent when the air is dry. It is well known that many static control products lose effectiveness when it is dry – just when you need them the most.

Hypothesis
The hypothesis that we are looking to test with these evaluations is that static is dissipated least effectively by humidity dependent products like SDT and more effectively by carbon loaded conductive ESD tile. Testing day's super-dry winter conditions eliminate any chance that relative humidity will enhance the discharge properties of any tiles. It is a known phenomenon in the industry that elevated relative humidity can increase the effectiveness of anti-static flooring, one very important reason floors should be tested at low relative humidity and without the aid of waxes or antistatic polishes.

Samples and Testing Methodology

Remembering that the ideal range for ESD flooring systems is 10⁵ to 10⁷, we decided to compare the results of the following flooring samples:

· SDT VINYL SAMPLE
Armstrong SDT Static Dissipative Tile (figure 1)
Samples that re provided by the manufacturer ‘s distributor

· Carbon loaded VINYL SAMPLE
Staticworx Foundation Series ESD Vinyl Tile (figure 2)
This sample was pulled from the Staticworx warehouse of samples

 

· EC RUBBER SAMPLE
Staticworx EC ESD Rubber (figure 3)
This sample was pulled from the Staticworx warehouse of samples

 

   (figure 1)  

   (figure 2)    

  (figure 3)

 

The size of the sample does not influence the effectiveness of the results of this test. These sizes appear as provided by the manufacturer. All samples are shown here, prior to testing, on a standard 8.5” x 11” piece of paper.

 

To conduct the test, we used:

·  Prostat, PRS-812 Resistance Meter (figure 4)

· Copper stripping that Staticworx supplies with all ESD flooring orders

· The three flooring samples listed above.

 

 

(figure 4)

 

Any easy way to determine if a flooring material can be grounded effectively is to measure its resistance with a megohm meter (see figure 4.) A good reading is usually below 1,000,000 ohms, that’s 10⁶ in ESD speak and on the meter it’s represented as “1.0 E 06”. An unacceptable reading is any reading above 3.5 E 07-0—it’s critical to understand that the meter’s highest measurement is 10 E 10 and lowest reading is 0 E 00. According to ANSI/ESD S20.20-2007 the system ground should always measure below 3.5 E 07.

 

Sample Testing

After connecting the meter to the two-weights/conductive cords, we placed each sample with its midline on the copper-grounding strip. Then, we connected the meter—one weight on the copper strip and one on the flooring sample. At this point, we turned on our meter and measured electrical resistance. Here are the results.

 

  (Figure 5)     

 

 (Figure 6)         

 

 (Figure 7)

 

In figure 5, the Armstrong SDT Vinyl Tile sample, reads 2.8 E 09, or 2.8 10⁹. In figure 6, the Staticworx Carbon loaded Vinyl Tile sample, reads 8.7 E 05, or 8.7 10⁵. In figure 7, the Staticworx EC Rubber sample, reads 9.8 E 05, or 9.8 10⁵.

 

Test Results

As hypothesized, the tests confirm that SDT is the least effective conductor of static; Carbon loaded ESD tile and EC rubber flooring conduct static most effectively - regardless of the dry conditions.

 

Conclusion: What does this mean?

The main purpose of static control flooring is to prevent discharges between people and static sensitive electronic assemblies. A good static control floor must safely ground static charges away from people regardless of environmental factors. A floor with poor or no conductivity, like Armstrong SDT, cannot effectively ground static charges because the resistance is too high. A high resistance (ohms rating) prevents charges from reaching ground. At low humidity, static charges will actually accumulate on a people as they walk on SDT. Carbon loaded flooring like Staticworx vinyl and EC rubber will perform equally well regardless of relative humidity.

 

Read more about how Staticworx ESD, Conductive Solid Vinyl Tile (wax-free) compares to Armstrong Static Dissipative Vinyl Tile (requires wax) on the Staticworx website >

Polyurethane is an insulator and a static generator

QUESTION:We are considering installing ESD tile in our facility. We have heard that tiles with polyurethane coatings (PU) might be easier to keep clean. Is this true? Can you recommend a floor that requires low maintenance?
Josh, Androgon Networks

 

ANSWER:
Polyurethane (PU) coatings are used by luxury vinyl tile (LVT) manufacturers. A coating of PU helps reduce the use of waxes and sealers on flooring installed in retail spaces, hospital corridors, shopping malls etc. Unfortunately PU is a non-conductive coating so defeats the purpose of the conductivity of the tile. That’s why they shouldn’t be used on floors that are intended for low static generating applications. This coating would insulate access to the conductive, carbon matrix sealing it inside the PU, keeping the tile from eliminating static effectively.  (See the Staticworx illustration on how conductive tile works > )

 

 

The PU coating would increase the electrical resistance of the tile leaving the floor unable to meet ANSI/ESD S20.20-2007 ESD standards. PU is an extreme static antagonist making it a major static generator; a floor coated with PU would allow for the accumulation of high static charges on people when they walk on the floor with any shoes.

 

If you think maintenance will be a major problem in your facility, you should at least consider a precision milled ESD tile with high vinyl content. These tiles are commonly called solid vinyl tile (SVT.)  The surface of SVT can be buffed and returned to its original appearance regardless of age, traffic or soiling. The properties run all the way through the thickness of an SVT tile so you never need to worry about abrasion affecting performance. The precision milling ensures a tight gap-free installation. Tight seams prevent that ugly dark line that often appears in between VCT tiles.

 

You may also want to explore EC rubber flooring. Unlike vinyl, rubber doesn’t have any pores that could trap dirt in the first place. And, conductive rubber is the only floor that will reduce static on people wearing standard street shoes. All other resilient ESD flooring requires the use of static protective footwear. EC Rubber is the most fault-tolerant ESD flooring available.

Did you know that most static control flooring can’t eliminate static on people if they are wearing standard footwear?

That’s a big deal; workers in data centers, call centers and control rooms don’t wear special shoes. Therefore, a properly specified static free floor needs to perform regardless of the type of footwear worn.

A recent study at MIT Lincoln Laboratories revealed that EC rubber inhibits static 10 times more effectively than other static control flooring options−regardless of footwear. The study determined that subjects wearing standard “street shoes” will not generate more than 0.1 kv (< 100 volts) volts when walking on properly maintained EC rubber flooring. The same subjects accumulated fewer than 10 volts when wearing special footwear. (See tribo-electric charging image to understand this concept.)

EC rubber is extremely versatile
It can be installed on bare concrete or over access flooring panels in data center and control room applications. It meets or exceeds all the ANSI/ESD standards for electronic handling requirements. It even addresses DoD Manual 4145.26-M for explosives handling.  It can even be installed using a dry adhesive system so that the space can be shut down for as little time as possible.

 

Contact Staticworx at 617-923-2000 to review options available in tiles or sheets.

VCT (wax-required) tile vs. ESD (no-wax) tile: lifetime cost vs. which has greater anti static qualities

QUESTION
Our management is considering installing a standard VCT and using static dissipative wax vs. installating a no-wax, non-porous ESD tile like Ameriworx or Foundation series tile. I am trying to evaluate the cost differences between the 2 options as it's my opinion that the wax requires much more maintenance and poses a greater risk to the products we test. Can you advise me whether this is an accurate opinion?
-Dale

ANSWER
The short answer is, yes, The maintenance cost associated with ESD wax quickly accummulates negating any money saved on the original VCT. Conversely, Staticworx Vinyl Tiles (Ameriworx and Foundation) are both economical and low-maintenance.

You may want to add a technical argument in addition to your concerns about maintenance. I assume you will be trying to meet ANSI/ESD standards. The recommendations for flooring in ANSI/ESD S20/20-2007 require a system resistance below 35 meg-ohms. System resistance is the aggregate resistance of the person, footwear, flooring and connection to ground. If ESD wax were used as the primary ESD flooring surface, it would mean that the wax would need to measure well below 35 meg-ohms (< 3.5 X 10E6 ) at all times. Manufacturers of ESD wax always specify the wax will measure as high as 1billion ohms – almost 2 orders of magnitude over the recommended limits for ANSI/ESD S202.0 system resistance.

These articles might prove useful in presenting your case:

• ESD Compliance
• Taking the Mystery Out of ESD Floors
• ANSI/ESD S20.20 Standards (login to ESD Association website to download, free)

Bubbles in Flooring: Scenarios and Causes

Staticworx staff recently fielded a call from an installer who was encountering bubbles in a flooring installation. Here's an outline of problems and causes that might help others. Check out Staticworx.com's articles section for additional ESD flooring relevant articles or contact us at info@staticworx.com or by phone at 617-923-2000 with questions regarding how to deal with bubbles in an installation.

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Bubbles in Flooring: Scenarios and Causes

Scenario #1: No Adhesive Bond to Concrete

Findings

The bubble has been cut open to reveal that the adhesive did not bond to the concrete. Adhesive is on the back of the flooring but there is little to none on the surface of the concrete.

Cause(s)

Contamination of the concrete or moisture may be the cause of the bubble.

1.   Check for signs that the following might have been used and not fully removed from the substrate:

·        bond breaker

·        sealer

·        curing agents

·        oil

·        paint

·        old adhesive

·        oil/wax based sweeping compounds.

2.   Adhesive will not stick to a contaminated surface. Determine whether  moisture is the reason for the bubble. If so, there may be a little more adhesive on the concrete and the bubble may take a little longer to develop.

Scenario #2: Adhesive Stuck to Substrate, Not Flooring

Findings

There is adhesive on the concrete and none on the flooring.

Cause(s)

There could be three (3) possibilities:

1.   Improper rolling.

2.   The adhesive was too dry, therefore no adhesive transfer to the flooring.

3.   The back of the flooring was contaminated (dust or similar).

Scenario #3: Smoothing Compound Stuck to Flooring, Not Subfloor

Findings

The smoothing compound has released from the subfloor and is mainly bonded to the back of the flooring, including adhesive.

Cause(s)

This is a sign of moisture, contaminants or a non-porous subfloor skimmed with smoothing compound and/or Statbond Acrylic Adhesive used “semi-wet”.

Scenario #4:  Adhesive Independent of Flooring or Subfloor

Findings

You find adhesive on both surfaces (subfloor and flooring installed), with adhesive squashed in the center.

Cause(s)

This means that early traffic on the floor produced a bubble. Rolling carts, hand trucks, etc. will squash the adhesive creating a very weak bond.

Scenario #5: Bubbles Appear Days After Installation

Findings

Bubbles appeared a few days after installation, not right away.

Cause(s)

Bubbles due to high Moisture Vapor Emission Rate (MVER), in general will show up at a later time after the installation is completed. You will find underneath that the adhesive is getting “chewy”, a very dark surface on the concrete or in some cases standing water.

What types of precautions are required to prevent static on people in mission critical environments?

This common question usually involves concerns about the need for special footwear in addition to a special static control flooring.

 

Test results from MIT Lincoln Laboratories demonstrate that a static conductive rubber (not static dissipative) can significantly inhibit the accumulation of static electricity on people, regardless of footwear.

 

 

This data solidifies the concept of installing an EC rubber floor in mission critical spaces like data centers, Server rooms, 9-1-1 Dispatch Call Centers, Command centers, Flight control Areas, Telecom Closets or any space where it is likely that people wearing standard footwear might contact sensitive electronic equipment.

Confused? Read my recent article about the difference between static dissipative and static conductive.