Don't Get Stuck Referencing The Wrong ESD Flooring Test Methods
ANSI/ESD Test Methods Are Different than EU Standards
ANSI/ESD S7.1 versus EN 1081
Note: this information pertains to flooring concerns associated with ESD protected areas (EPAs) in electronics manufacturing and handling. This information is not pertinent to static control concerns in end user environments. If your interest focus is on antistatic flooring for data centers, server rooms, 911 call centers, School Labs, Networked offices, FAA flight towers, Communication rooms or telecommunication areas go to this page for technical articles.
A military electronics company trying to meet static control requirements in ANSI/ESD S20.20-2007 contacted us about a problem they were having with their new floor. The new floor was purchased under the assumption that it would meet all the requirements of Table 2 in the S20.20 document. The caller explained that the floor wasn’t meeting any of the requirements even though the manufacturer assured them nothing was wrong with the flooring. The electronics manufacturer described the floor as a static conductive linoleum sheet floor; it was made in Europe and new to the US market. After reviewing the client’s test data I agreed to meet with and help them find out why the floor wasn’t doing what it was supposed to do.
Immediately after I arrived, I was asked to measure the floor with my meter, a Prostat megohm meter. After several tests, we quickly concluded that our meter and theirs were arriving at consistent results; the floor was incapable of meeting any of the S20.20 requirements; it was far too resistive. The resistance to ground exceeded 1 billion ohms (1.0 X 10 E9.) The system resistance exceeded 3.5 X 10 E7. The building representative was extremely agitated because he knew it would be difficult to shut down the facility and replace the floor. They told me this floor was a value engineering substitution late in their project. They had been guaranteed this floor would do everything the originally specified floor was supposed to do.
Upon review of the floor manufacturer’s documents we discovered the real problem with the floor. The manufacturer’s specifications referenced a resistive properties test method called EN 1081. Unlike North American standard test method ANSI/ESD S7.1, the European method tests floors using a much higher applied voltage. EN1081 actually references an applied voltage of 500 volts. Higher applied voltages cause electrical resistance to drop. The greater the applied voltage, the lower ohms resistance you will see. Using ANSI/ESD methods, the floor measured extremely high at the specified applied voltage of 100 volts. Unfortunately for this end user, they were probably stuck with the floor without recourse because no one in their organization had picked up on the test methods referenced by the European manufacturer. It was clearly printed on their spec sheet.
There was one other forewarning that this floor may not have been the right option: Despite their reference to the static dissipative value < 1.0 X 10 E8 (EN 1081), the manufacturer’ brochure recommended the floor for “areas with sensitive equipment.” They made no reference on any of their promotional materials to electronics manufacturing, EPAs or ANSI/ESD S20.20. There was no mention of a lifetime static control warranty.
- Only accept materials that have been specified using ANSI/ESD Standard Test Methods: www.esda.org
- Always ask for test data from independent labs when qualifying any kind of static control flooring. Labs like Fowler Labs (www.sfowler.com) can perform the full battery of tests needed for qualifying floors to the requirements in ANSI/ESD S20.20.
- Insist on lifetime static control warranty.
- Always include in your contract a requirement for a post installation certification like our-GroundSafe Audit - demonstrating that the flooring meets Method One in ANSI/ESD S20.20 for Personnel grounding. Method One requires ANSI/ESD S97.1 System resistance testing. System resistance tests both the floor and the static control footwear in combination. An acceptable system resistance measures below 3.5 X 10 E7 ohms. This is the most important criterion. ANSI/ESD S20.20 confuses many engineers; without reading closely, it’s easy to conclude that the floor merely needs to measure below 1.0 X 10 E9 using test method s7.1-2005. This is a fallacy.
You might also take a look at this video for further understanding. Static dissipative versus conductive video