“Dissipative floors should also be installed in hospital corridors”
Electrostatics inspector Tobias Buob tested the new coating agent Wetrok Mepol Ohm to determine its conductive and dissipative capacity. His verdict: The product delivers. We interviewed him to discuss what dissipative floors are, why the application of a coating is recommended and which flooring materials are inherently dissipative.
Mr Buob, you are the owner of STATECH SYSTEMS AG, a certified inspection body for electrostatics. What does your work involve?
A lot of my friends still don’t understand exactly what I do for work (laughs). I’ll attempt to explain it: International standards prescribe special floor coverings for certain types of rooms. Specifically, floors that prevent electrostatic discharge. For example, this would be the case in operating theatres (to protect people), in production facilities for electronic components (to protect against damage to the equipment) or at a chemical manufacturer (to protect against the risk of explosions). The floor coverings installed in these rooms must be conductive/dissipative – in our technical jargon, we call this ESD flooring. Similar dissipative requirements also apply for other protective elements such as shoes, tables or chairs. In other words: The materials must be able to safely divert electrical charges into the floor. Our job is to assess such floors or other protective elements at external companies and to review whether they actually fulfil their dissipative function. If they do, we issue a certificate.
And if they don’t?
In that case, the floors need to be recoated or replaced – and then inspected again.
What exactly does electrostatic charge mean?
An electrostatic charge is generated by the separation (friction) of different materials. For example, the friction of shoe soles against the floor can generate an electrostatic charge in that person which is then discharged as a small electric shock. Example: You walk on a floor wearing shoes with plastic soles. The charge is unable to dissipate into the floor, so it accumulates. Afterwards, you touch a door handle (electrically conductive material), and zap – that’s when the discharge happens. The result: It “shocks” you or you get “zapped”.
You and your team are experts in conductive and dissipative materials – do you also sell ESD products yourself?
We do, actually. We first started selling ESD protective materials around 30 years ago. And still today we develop, inspect and sell dissipative/conductive protective shoes, chairs, packaging materials, table mats or floor coverings – simply everything you could need in an office or adjacent areas. But around the 2000s, more and more people started asking us to provide our inspection services to third parties as well. So we established another mainstay in 2006 with our certified inspection body for electrostatics. At the same time, it is very important for us to preserve our independence and credibility: We act either as a vendor OR as an inspector – never both at once.
What is the difference between an anti-static floor, a dissipative floor and a conductive floor?
Let’s start with the lowest safety level: Anti-static floor coverings weaken the static charge of objects. This type of floor prevents the phenomena of “hair standing on end” or painful discharge sparks – they are often found in offices. Most of the time, the users of the room have no idea that they have an anti-static floor covering beneath their feet. These are frequently textile floor coverings for which the choice of material is the decisive factor. You can see this in the following example: When you pull off a cotton jumper, there is usually a minimal amount of crackling – but when you take off a polyester jumper, the crackling (= electrostatic charge) is much stronger.
At the second level we have dissipative floors. These counteract electrostatic discharge and ensure a slow, gentle discharge. Dissipative floors can often be found in server rooms or production halls for electronic components. A person can only accumulate a very small charge on these floors, and this is then discharged directly back into the floor. If a person touches a device, it is not possible for a dangerous electrostatic discharge to occur because there are no high charges present. We carry out about 95% of our measurements on dissipative floors.
The highest level of safety for highly sensitive rooms is provided by conductive floor coverings. These floors immediately reduce voltages to a minimum. As a result, they are used to protect people in operating theatres or environments where there is a risk of explosion (e.g. chemicals lab). In operating theatres there is an increased risk of ignition due to the oxygen-enriched atmosphere. An electrostatic spark can easily cause a fire here. With conductive floors, electric charges are immediately and fully diverted into the floor.
Why aren’t dissipative floor coverings required everywhere?
Conventional floors are absolutely sufficient for most types of room usage. For example in private households: If you wear a synthetic jumper and you get “zapped” when you touch your cat afterwards, this is not dangerous. Furthermore, ESD floors are not the cheapest option and they are primarily functional objects – the visual design possibilities are limited.
Does that mean you can recognise an ESD floor? If so, based on what characteristics?
Yes, usually if you take a closer look you can determine whether it is an ESD floor. A special substance always has to be mixed in when manufacturing a floor to make it dissipative. With linoleum and PVC floors, you can see black dots consisting of carbon or graphite, with epoxy resin floors you can tell they are dissipative from the small, linear conductive fibres, and polyurethane coatings are generally grey in colour because the conductive pigment used is grey. The only exception is concrete: This material is inherently dissipative.
Are there room types without ESD floors where you believe dissipative floors would be preferable or useful?
Absolutely! In hospitals, it has been specified that ESD floors are required for operating theatres. But in my view, dissipative floors are also urgently needed for corridors and patient rooms. Some care staff will be truly afraid of moving a patient’s bed (= causing friction) because the bed frame could accumulate high charges that can cause extremely painful discharges. This would be easy to prevent using ESD floors.
Is it necessary to apply a coating on dissipative floors?
In principle, dissipative floors also work without a coating. But a coating helps to protect the floor and provides various advantages. So I would absolutely recommend the application of a functional coating.
What are the specific advantages of applying a coating?
The coating protects the floor against discolouration, prevents persistent dirt residues and simplifies cleaning. In short: The protective coating makes the floor more resistant – this is an important factor, because these floors are often cleaned incorrectly for years. And the most persuasive argument for a good coating: It enhances the floor’s dissipative characteristics on the long term. Plus there’s another aspect we tend to forget: ESD floors are sometimes a bit slippery – here as well, a coating can help to ensure improved tread safety.
What characteristics does a coating agent have to provide?
It absolutely must not have an insulating effect! Certain coating agents form an insulating layers after multiple applications – particularly in places with less foot traffic, under tables for example. This is very dangerous, as it will cause the floor to lose its dissipative capacity. Accordingly, the product should be as long-lasting (a single application) and easy to use as possible.
You recently tested Wetrok Mepol Ohm, a new coating agent for dissipative/conductive floor coverings. What is the procedure for this kind of test?
In the first step, we carried out basic cleaning on six linoleum floor discs (sections of dissipative floors) and then pre-conditioned them for 48 hours at a room temperature of 23 degrees and 12% relative humidity (ESD standard). After that, the “Before” values of the discs were measured under the specified environmental conditions. These extreme test conditions are important in order to determine whether the product also works in winter. In the next step, we coated the discs with Mepol Ohm. Here we applied a different number of layers to each disc. Afterwards, we left the discs to dry for another 48 hours. Then it was time for testing and determining the “After” value: To do this, we measured how the dissipation values had changed. In order to obtain an absolutely reliable result, we measure this in four ways: with a point-to-point measurement (to obtain this, we place two electrodes on the floor and measure the resistance between them), an earth resistance measurement (here we measure the resistance of an electrode “against” the earth potential), a system resistance measurement (to obtain this, we integrate a person standing on the floor into the measurement) and a walking test (here we measure the body voltage of a person walking on the floor). The last two tests are the most important because they answer the following question: How quickly is a person able to discharge into the floor and how much charge can a person accumulate when walking? The result must not exceed specific limit values.
What is your verdict or the test results for Mepol Ohm?
The product completely convinced us! Particularly for the last two types of measurement, the resistance (ohms) was lower than the “Before” value (uncoated floor). This demonstrates that the electrostatic charge accumulated by a person on a floor coated with Mepol Ohm is dramatically reduced when compared with an uncoated floor – an outstanding result!
How would you rank these results compared to competing products that you have tested?
Reducing the electrostatic charge accumulation by two thirds is a very impressive result. Normally, the companies we test are happy if their coating agent has no effect or does not significantly impair the conductivity of the floor. The opposite is true with Mepol Ohm. This product actually improves conductivity!
For whom would you recommend Mepol Ohm?
Any companies that are thinking about purchasing new dissipative or conductive floors. I would also recommend it for all establishments with older ESD floors that would like to mitigate damages by applying a coating.
Would you like to learn more about Wetrok Mepol Ohm?