FLOORING
Understanding the risks from electrostatic discharge
There are a range of different environments within a hospital that require shielding from electrostatic discharges (ESD) for the protection of patients, staff, and equipment. Here, Garry Bateman, head of Technical Sales and Support at Forbo Flooring Systems, discusses how static discharge can be controlled with the specification of ESD flooring, while still maintaining the highest standards of hygiene.
In hospital areas such as operating theatres, intensive care units, and imaging diagnostic facilities, the flooring presents its own unique set of challenges. Not only does the choice of floorcovering need to comply with strict hygiene standards to prevent the spread of hospital- acquired infections, but the generation of electrostatic charges can pose a serious risk to sensitive electronic equipment and devices.
What is ESD and what are the risks? The cause of ESD is the presence of static electricity, which can be generated in a number of ways. It is the build-up of charge (electrical potential difference) between two surfaces, caused by the exchange of electrons from one to the other. This is most commonly caused by the contact and separation of two surfaces in an effect known as tribo- electric charging. Different materials will generate static electricity at different rates, but one of the most common sources is the friction of people walking across a floor. This is referred to as Body Voltage Generation (BVG). Electrostatic discharge is triggered when two surfaces with a potential difference come near each other, and there is a sudden flow of electrons
ESD flooring may be required for hospital operating theatres and other areas where sensitive scanning and imaging equipment is located.
from one to the other to return to their neutral or uncharged state. The discharge is measured in Volts, and can vary significantly in size – from small discharges that are generally imperceptible to people, to large discharges that can be painful to experience and result in a visible spark. For example, at 3000 Volts most people will feel the static discharge, while at 5000 Volts a visible spark will appear, and at 10,000 Volts the snap of the spark from the static discharge can be heard.
A discharge below 2000 Volts will not be felt by a person, but it is still there, and is potentially damaging to electrical equipment. In fact, just 100 Volts is enough to damage some electronic components, and for the most highly sensitive elements, just 20 Volts may cause harm.
As SD and EC flooring products have different resistance characteristics, the choice of product depends on the level of electro-sensitivity of the equipment and environment.
Equipment damage risk Hospital environments contain many pieces of equipment that can potentially be damaged by ESD. The damage caused is broadly categorised either as a catastrophic failure or latent defect. In a catastrophic failure it is usually an electrical path in a component that has been irrevocably damaged and must be replaced. A latent defect may not result in an immediate failure, but can cause a degradation in function, and these defects can build up to cause more serious issues. Static has always been an issue in hospital environments. In the past it was flammable anaesthetic gases that posed the risk, but with these being phased out, the potential damage to electronic equipment is the main risk. However, hospitals should not rule out the risk of ignition of other flammable materials. For example, many skincare products used to treat eczema and psoriasis are paraffin- or petroleum-based. These have been
October 2020 Health Estate Journal 65
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