Ever since static electricity was recognised as a problem, efforts have been taken to control the risks. Centuries ago, the biggest issues caused by unwanted Electro Static Dischar¬ge (ESD) events was the ignition of gunpowder storage and other explosive or flammable material. As the electronics industry started to grow and electronics beca¬me smaller and more sensitive; ESD control became a relevant topic for many companies.
In most sensitive environments where critical processes take place, ESD (electrostatic discharge) – and particle control is required. These environments are also known as ‘controlled environments’ and most common in the electronic industry, defence, research and healthcare segments. Think of electronic production areas, laboratories, clean rooms, operating theatres and even large financial data storage facilities.
The flooring requirements can be very specific and ensure a safe environment for both people and equipment. Static discharges can be unpleasant for patients and employees and sensitive medical and electronic devices can be negatively affected by static charges.
Forbo’s under control portfolio
All collections from Forbo that offer a solution for the most demanding controlled environments, are bundled in one portfolio called the Under-Control portfolio, which, includes:
- Colorex Tiles (adhered and loose lay)
- Sphera Homogeneous sheet SD and EC
- Marmoleum Ohmex Sheet
Each collection has its own properties and benefits. The best solution is usually dependant on the specific customer requirements.
Correct installation is the key for controlled environments and should be taken seriously. Often a system solution is required and involves the use of special accessories like conductive adhesive, copper strips and even conductive primer. The system won’t work if not connected to an earthing point and tested by a licensed electrician.
How does ESD flooring work?
Electro Static Discharge. ESD events take place when the electrostatic charged material returns to its neutral/uncharged state. It can be a miniature spark, which, passes from one electrostatic charged surface to another surface. ESD flooring limits the electrostatic charging of materials or people. The floors ensure that when materials get charged, the charge is discharged and grounded from people through conductive shoes to the floor in a controlled and even way.
What is the difference between dissipative (SD) and electro conductive (EC) flooring?
The difference between SD and EC flooring is in the degree of electrical resistance (the ability to lead away electrostatic charges). An EC floor has a lower resistance than a SD floor, which means charges flow more easily through the surface of the floor to ground.
Conductive flooring is not by definition better than dissipative flooring, it depends on various circumstances what floor will offer the best solution.
Installation guidance SD and EC flooring
The installation of Sphera SD | EC rolls and Colorex Tiles should be carried out in accordance with AS 1884-2012 resilient flooring standard. Always conduct moisture and alkaline tests on all substrates and ensure moisture barriers were needed. Correct temperature for installation and acclimatising products on site is essential.
When installing vinyl conductive floors, low emission EC1 (plasticizer resistant, acrylic dispersion) adhesives are recommended, such as Forbo Eurocol ‘641 Eurostar Special EL’ (conductive adhesive) and Forbo Eurocol ‘640 Eurostar Special’ (non-conductive adhesive) and always in combination with a copper strip. Use a TKB S1 trowel for Forbo Eurocol 641 (conductive adhesive) and TKB A2 trowel for Forbo Eurocol 640 (nonconductive adhesive) to apply the adhesive. Marmoleum Ohmex should be installed with a conductive linoleum adhesive (615 Eurostar).
Check the trowel to ensure that the proper, specified trowel notch is used and maintained. The adhesive must be spread evenly over the entire floor area including edges.
There are two installation options for Sphera EC | SD sheet. We recommend using a conductive primer for all ESD installations.
SPhera Option A – Use of conductive and non-conductive adhesive.
A 100 mm wide band of conductive adhesive must be applied over the copper strip (see image below). The remaining areas can be installed with ‘normal’ low emission EC1 adhesive.
- Stick down the copper strip
- Spread the conductive adhesive on top of the copper strip
- Spread the normal adhesive & install floor
Sphera Option B – The entire floor is installed with conductive adhesive.
- Stick down the copper strip
- Spread the conductive adhesive
- Install the floor
Electrical grounding – installation and layout
Before starting the installation make a floor plan. Position of sheets and right position of the copper strips. Position of seams (with or without copper strip connection) copper strip(s) for electrical grounding must be installed first. Self-adhesive copper strips are recommended.
The electrical connection of the copper strips to the grounding point(s) must always be made by a qualified electrician.
Copper Strip layout for rooms smaller than 40 m²
Lay a strip of copper tape extending approximately one metre onto the subfloor allowing enough excess to extend up to the nearest grounding point. This layout is recommended for rooms where the shorter side of the room is less than 10m. Lay the copper tape to create a circuit as shown in Figure 1 below. Punch the strip intersection with a centre punch to ensure proper contact and test the conductivity of the copper strip circuit with an appropriate testing device prior to starting installation of the material. Avoid a seam at grounding point(s). If you weld and you need to trim the weld you may damage or cut the copper strip?
Layout for rooms larger than 40m²
This layout is recommended for rooms where the shorter side exceeds >20m.
Lay the copper tape to create two circuits on opposite side of the room as shown in Figure 2 below. Punch all strip intersections with a centre punch to ensure proper contact and test the conductivity of the copper strip circuit with an appropriate testing device prior to starting installation of the material. At all cross seams, a 1m length of copper tape should be fixed to the subfloor along the centre line of the sheet length equally spanning the cross seam as shown below.
Colorex Tile uses a similar procedure with conductive adhesive and without the cross-join copper tape. Colorex Plus EC loose lay system uses no adhesive and just copper strips.
Marmoleum Ohmex – Natural dissipative flooring
Ohmex requires a slightly different procedure. For floor areas less than 36m² a 15cm length of copper tape (10mm wide and approximately 0.1mm thick) should be adhered to the subfloor using 615 Eurostar lino EL conductive adhesive at a suitable point in the floor to be connected to earth. The strip should protrude sufficiently from the edge of the flooring installation to allow connection to the earth point. For areas over 36m2 a strip of copper tape should be adhered to the subfloor running the full length of the floor area spaced at 6m intervals. Further strips should then be laid at right angles to the first strips at the same 6m spacing forming a 6m x 6m square grid covering the entire floor area. One of the strips should protrude sufficiently from the edge of the flooring installation to allow connection to the earth point.
After conductive installations: Do NOT apply any wax or emulsion floor finishes in ESD protected area as these will adversely affect the conductive properties of the floor.
Electrical resistance testing after installation: Point-to-ground electrical resistance tests according to approved relevant standards should not be carried out earlier than 14 days after installation. First random control measurements can be made after 24 hours.
To find out more contact Forbo technical on firstname.lastname@example.org