In this guide, we cover the basics of static charges and electrostatic discharges (ESD), and how antistatic floors work to remove the static charges.
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Static electricity discharges, which can easily impair or destroy fragile electronic circuitry, are a common factor that electronic equipment must be protected against. This is exemplified by the fact that some electronic components can be damaged by an electrical discharge of around 300 volts. However, did you know that just one person walking across a floor can generate up to 3,000 volts?
As a result of this challenge, the electronics industry loses significant amounts of money each year due to damaged goods and broken equipment. To safeguard against this, facilities operating in this market sector should install anti-static flooring solutions as part of the overall ESD Management Scheme.
To ensure that a floor finish will meet the anti-static needs of a site, it is necessary to understand the location's operational activity, how the floor build-up works to eliminate this threat, and the role played by other factors such as testing and personnel clothing.
Simply put, movement between two surfaces can generate an electric charge, with at least one surface having a high resistance to electric current. The generated electric charge remains until it can be dissipated by an electric current or electrical discharge.
For example, when a person moves across a floor, they can build up a negative charge which increases the more the person moves around.
The process through which a person builds up an electric charge is known as triboelectric charging. This generated electric charge is known as a static charge.
If the stored static charge is significant enough, when a charged object nears a conductive or earthed object, the excess charge will flow between the two objects and neutralise. This phenomenon is an electrostatic discharge, which may produce a visible spark.
If the charged object is a person, the person would experience a mild static shock. However, if the electrostatic discharge passes through a piece of sensitive electronic equipment, it can cause irreversible damage.
While this phenomenon has obvious detrimental implications for the electronics industry, there are also a wide variety of locations where sensitive electronic equipment needs to be protected against electrostatic discharges. To name just a few, the healthcare industry utilises a large number of sensitive electronic life-saving equipment; the aviation industry must ensure that its machinery runs flawlessly in order to keep planes in the air; and any sensitive facility such as a data centre or a cleanroom.
In environments where flammable gases, solvents or dust are present, electrostatic discharges have the potential to be a dangerous ignition source! This eventuality is more common in the munitions and military industries, but it can be a concern in any R&D, production or healthcare environment where flammable elements are present.
The rate at which an electrical charge is dispersed is controlled by the material&#;s electrical resistance and is measured in ohms (Ω). The amount of electrical resistance relates directly to the material&#;s conductivity and ability to move charges out of the area. Essentially, the less resistance there is, the faster the charge can be removed.
For anti-static purposes, floors are ordered into different categories depending on how quickly electricity can move through them. Materials with the least resistance are defined as conductive, moving to dissipative floors that allow electricity to flow through at a controlled speed and floors at the most resistant end of the spectrum are called insulative.
A good way to think about this is to picture an electrical cable, with a highly conductive metal in the middle which the electricity can move through at a rapid pace, compared to the plastic wiring on the outside which is insulating and through which the electricity cannot move.
Anti-static floors ground the personnel as they move around the site, preventing damaging levels of static charge from accumulating. This is achieved by constructing a flooring build-up designed to safely transfer the charge from a person to a defined earthing point. In practice, there are several ways that this can be done. We will focus on one of the most popular and effective methods.
The process begins with a resin coating that incorporates specialist conductive materials within the floor. These materials take the charge from people walking across the floor&#;s surface when their feet come into contact with them and this starts a chain reaction that results in the charge being removed from the area.
Next, the charge hits a conductive primer that has been filled with carbon to ensure a very low level of resistance. Finally, the charge then hits a copper tape buried under the floor coating which is connected to a safe earthing point.
It is important to remember that this is an ideal scenario, and there may be more or fewer steps in practice. It is possible to make a floor that removes static charge without using copper tape, but it will not be as conductive as one that does.
Copper grids under the primer are an important part of the process, as installing this tape helps to make the flooring system much more conductive.
To recognise the role that the tape plays, it is important to understand its impact on surface resistance. Resistance to earth is measured from a fixed earth point on the floor. The distance from the point of measurement to the earth point has to be specified, if it is not then it should be assumed that it could be at any point on the floor.
This has a major impact on the need for a copper grid, since for materials that are not conductors then the measured resistance will increase when the distance between the measuring points is increased. Thus, the surface resistance will not change across a floor because the electrodes are a fixed distance apart, so the resistance to earth will increase as the electrode is moved further from the earth point.
To combat this, a conductive copper grid increases the size of the earth point and ensures that all parts of the floor are close to the earth point.
The grid must be continuous in order to function, and all grid bays must be connected and/or earthed in some way. In practice, this may cause some complications during the flooring project. One potential complication is that expansion joints might break the flow of the tape. To avoid this, the tape needs to be put down into the joint&#;s walls and run up the other side to ensure that it is not broken. Alternatively, multiple earthing points should be connected to ensure each bay is fully grounded.
Typically, the copper is applied in 3 m² grids to ensure that everyone moving across the floor is close enough to a line of tape. Any areas of the floor that do not have copper tape nearby risk being much less conductive than the rest of the floor. However, due to the size or shape of the room, it may not always be practical to install these grids.
In these cases, it can be useful to install the copper in a &#;crows&#; feet&#; formation &#; the tape spreads out from an earthing point in a number of straight, equally spaced-out lines.
An earthing point is simply an electrical connection that allows any charge that has been transferred to the floor to safely escape to earth. Without an earth, the floor cannot be considered anti-static because any charge that enters it will simply accumulate in the floor.
In practice, the typical method of creating a reliable grounding point is to connect to the facility&#;s existing earthing system.
One earthing point per 200 m² should be sufficient in most cases, but the exact requirements should be specified by an electrical engineer to ensure that the resistance or resistance to earth measurements are appropriate for the task at hand.
It is critical that personnel on site wear appropriate clothing to increase the likelihood that any charge built up within a person will be safely grounded.
In some facilities, employees wear wrist straps that are directly connected to grounding points in order to remove charges as quickly as possible. However, while effective, this is not always a practical approach because the straps can be very restrictive for the person wearing them.
To get the most out of an anti-static floor finish, anyone walking across its surface should be wearing special electro-static dissipative shoes. Without these specialised shoes, the static charge cannot be reliably grounded.
Depending on the nature of the facility&#;s operations, the antistatic flooring may also need to meet anti-slip requirements to safeguard against slip hazards. Specialised antistatic floor coatings with a textured profile would create safe, anti-slip surfaces for these specific work environments, protecting the users&#; wellbeing and safety.
Flowcrete's Flowcoat ESD (Antislip): Antislip antistatic epoxy flooring
The term &#;anti-static flooring&#; is frequently used as a generalisation for both electro-static dissipative (ESD) and electro-static conductive (ESC) floors. As previously stated, the proper definition is dependent on the conductivity of the floor, with conductive being any floor that has a resistance less than 1.0 × 106 ohms (1 million ohms), and dissipative being any floor that has a resistance between 1.0 × 106 and 1.0 × 109 ohms.
This is demonstrated by the fact that many resin flooring coatings can be either conductive or dissipative depending on how they are applied.
To put it simply, the greater the risk of danger from a spark or electrical discharge (shock), the more conductive the floor needs to be.
This categorisation into static conductive and static dissipative is especially useful for electronics areas where there is a risk of mains shock from hand tools.
There are numerous methods for measuring electrical resistance, and each method can produce different results for the same material, so it is critical to understand the specifics of the test method. The main distinction is the type of test, which can test for surface resistance or earth resistance.
The standard BS EN -5-1 includes a method for determining the resistance of a floor, which has become a popular choice in many countries. The standard details point-to-point conductivity testing using a meter to gauge the amount of resistance between two fixed points on the floor. The outcome of this test will determine whether the floor can be categorised as conductive, dissipative or insulative.
When testing the floor, it is best to move the contact points around to ensure that a footprint sized space has been checked, as this is the contact size that needs to be covered to ensure that any charge held by a person is transferred into the floor.
NFJ Product Page
In addition, it is advisable to check after each stage of the flooring project. This is because there may be failures beneath the floor coating that will go undetected if the test is only performed at the end. Ideally, tests should be performed after each stage, especially after the copper grid has been applied, and then again after the primer has been laid down.
Antistatic floors are specifically designed for use in cleanrooms and manufacturing environments where sensitive electronics, components, gases, solvents or even explosives are handled. Check out Flowcrete's antistatic flooring case studies around the Asia Pacific region, where Flowcrete antistatic flooring systems are used to meet the specific resistance requirements of the facility.
Here are a few selected case studies from around the region:
Further recommendations and advice are available from our network of regional technical and sales representatives.
This guide has been produced to provide an overview of when anti-static flooring is required and how it works.
View this guide in PDF format
Selecting the right industrial flooring for your production facility can be challenging, especially where identifying the most appropriate finish is concerned. That&#;s because there are several finishes, colours and materials to choose from, not to mention specific performance requirements to consider. A finish that meets the UK&#;s rigorous hygiene requirements for healthcare, for example, may not also be the natural fit for delicate manufacturing processes.
One of those factors to consider, relevant to a wide range of industries, is whether flooring needs to incorporate an anti-static finish. Our guide will help you establish whether you need anti-static, what types are available, what benefits to expect, and what options to consider&#;
Anti-static flooring in a nutshell
Some industrial environments are prone to generating electrostatic discharge (or ESD), a pulse of static electricity that is passed from a person or surface to another object. Although this static electricity conduction is not always apparent, in some cases it can be sufficient to generate a spark or tiny blue bolt of electricity.
At the harmless end of the scale, an electrostatic shock manifests itself as a mildly uncomfortable or surprising shock. In the presence of flammable chemicals, materials or gases, however, an electrostatic spark can be highly dangerous and potentially even catastrophic. In those cases, installing anti-static flooring is an essential step in creating a safe environment for workers and visitors, since (as the name suggests) anti-static industrial floors insulate the environment against this electrostatic charge.
Where Anti-Static flooring is essential
According to UK Health and Safety regulations, anti-static flooring is mandatory in certain industries as the most basic safety precaution. Chemical manufacturers and processors, as well as any businesses that use flammable chemicals or materials in their operations, need to create static-free work environments to avoid igniting chemicals, fumes or even microscopic flammable particles.
Since electrostatic discharge can render sensitive electronic components useless, organisations that produce or assemble semiconductors or electronic goods need anti-static floors to mitigate the risk of electromagnetic charge accumulation.
Additionally, any operations that rely on uninterrupted or guaranteed use of specialised electronic items, such as hospitals or air-traffic control rooms, should take precautions to avoid static. Other examples of UK industries that require anti-static flooring include munitions or pyrotechnics manufacturers, military operations, micromechanics, optical lenses, photographic film, lasers, biotechnology, pharmaceuticals, surgical implant manufacturing, medical environments and even some food and beverage production environments.
Anti-static floors work by taking the static electricity that builds up naturally in any environment and transferring it through the floor to ground. By grounding the charge, anti-static flooring prevents the ESD from building up and discharging into the environment, where it could be destructive to goods or dangerous to people.
Paradoxically, almost any movement creates static electricity, no matter the environment or activity. Office workers will have experienced the build-up of static from walking across the carpet, while those operating vehicles, heavy equipment or machinery over a warehouse floor will be aware of the static charge these generate.
The majority of electrostatic discharges are below 3,500 volts and totally undetectable to people, so we&#;re not even aware of most of the potentially dangerous ESD happening all around us. Anti-static flooring, however, is capable of capturing all those charges and grounding them before they cause reactions.
Choosing an Anti-Static Floor
Anti-static flooring covers many uses, and as a result, there are many factors to consider when choosing which type of anti-static floor to install.
The first step is to understand the risks and requirements for your specific use case, including how electrostatic energy is generated in your location, the estimated strength of your average ESD and the potential consequences of electrostatic discharges in your facility.
Next, it&#;s important to understand the subtle but important differences in static control terminology to help you decide which type of anti-static flooring is right for you.
The resistance or impedance of anti-static flooring is expressed in ohms (Ω), a unit of measurement named after German physicist Georg Ohm, creator of Ohm&#;s Law, which governs electrical currents through conductors. Anti-static flooring options include conductive and dissipative systems, which offer different ranges of electrical resistance; in general, conductive flooring offers a resistance of up to 1 mega Ω, and static dissipative flooring provides resistance between 1 mega Ω and 100 mega Ω.
In simple terms, higher resistance equals lower conductivity of energy; however, that doesn&#;t mean that lower resistance is necessarily the better option for anti-static floors. In fact, in most &#;mission-critical&#; environments like emergency call centres or air traffic control towers, grounding standards recommend static dissipative flooring over conductive flooring options. Ultimately, the specific needs of your facility will govern which choice is right for you.
Tips on choosing an anti-static solution
Even the most elaborate, well-considered anti-static flooring solution will fall short of expectations without professional expertise during installation. A reputable provider can make a huge difference in the effectiveness and longevity of your floor. In this respect, beware of price as a deciding factor and choose a provider or contractor based on their experience, reputation and reliability.
Where industrial flooring is concerned, the Total Cost of Ownership is the most reliable benchmark, whether the flooring is anti-static, concrete, resin or carpet. This cost reflects not just the installation, but also the maintenance and repair (as well as the warranties that cover them). Do a thorough check of the company providing the solution, including their history and reputation; no reputable provider will bristle at you doing your due diligence.
The importance of maintenance
Your industrial flooring provider should be able to give you a transparent forecast of maintenance and repair costs for your anti-static flooring. Bear in mind that epoxy anti-static floors cannot be overlaid as this will insulate the floor from the earthing points so the epoxy must be first removed back to the substrate, with new copper strips installed for re-earthing and grounding. The new epoxy coating is then installed with an additional 7 days before the epoxy fully cures.
Vinyl flooring will have a shorter life expectancy and a lower abrasion resistance resulting in the need for maintenance and ultimately replacement in a far shorter period. By contrast, PMMA flooring can be reverse-cured, which makes spot repairs easy to do. Get to know the needs of the floor types you&#;re considering and factor the expected costs of maintenance and repairs into your budget to get a true picture of how much a solution will cost.
Start with the sub-floor
No anti-static flooring solution performs independently of the sub-floor conditions, so it is essential to assess the quality of the site before installation. Contaminated concrete or moisture problems can lead to ineffective and even problematic flooring. Most issues can be solved ahead of installation&#;provided you are aware of them. Flooring manufacturers and certified contractors will be able to arrange for your sub-floors to be tested ahead of installation to help ensure the success of your anti-static floors.
Advanced anti-static flooring from Trazcon
Today&#;s leading anti-static flooring solutions have applied innovation through simplicity. Trazcon anti-static dissipative flooring offers an electrical resistance of ×106Ω < RE < 1×108Ω, making it an ideal solution for a wide range of anti-static flooring needs. Whereas traditional anti-static flooring was made up of a primer, copper strips, independent wiring and an epoxy coating that took seven days to fully cure (harden), Trazcon anti-static contains an anti-static filler powder in the seal coat and boasts an industry-leading one-hour cure time. As a result, the floor is ready for use just one hour after installation, yet any subsequent repairs can be made without digging up large sections of the floor or cutting channels for regrounding. As Trazcon anti-static is a dissipative floor the need for copper strips or earthing points is eliminated.
Floortech is the specialist UK provider of the PMMA anti-static flooring solution, which is highly recommended for laboratories, production areas, material testing zones, service workshops, automotive facilities, and electronic component areas. Our Trazcon® Anti-Static system is suitable for use in AtEx zones, offering protection for the storage of flammable liquids, gases, vapours and mist, as well as combustible dust.
For specifics about PMMA anti-static flooring, download the technical data sheet available from Floortech or contact our team of experts.
Contact us to discuss your requirements of anti static floor coating. Our experienced sales team can help you identify the options that best suit your needs.