Dreaded and dreaded in ATEX zones,static electricity requires special attention. The phenomenon is unavoidable and can present a danger on industrial sites, both to the durability of equipment and to the health and safety of personnel. So how do you protect yourself against electrostatic hazards in potentially explosive atmospheres?
How is an electrostatic discharge generated?
An electrostatic discharge (ESD) is generated whenever two bodies or materials with different static charges are brought into contact and then separated. This phenomenon is known as triboelectricity.
Inevitably, one of the two materials gains electrons and the other loses them, creating an electrical potential difference.Static electricity occurs when positive and negative charges combine.
These energy transfers are permanent and mostly imperceptible. In everyday life, they manifest themselves as a harmless micro-spark when putting on a sweater or rubbing a plastic comb against dry hair.
NB: insulating materials can carry electrostatic charges, which is why it’s also important to use ATEX equipment.
What is electrostatic risk?
Electrostatic discharges only become dangerous if the static charge is allowed to build up for too long.
On an industrial site, ESD can damage electronic equipment. Electrostatic charge can accumulate on insulated metal equipment, insulating materials or non-conductive powders and liquids.
Staff may also be at risk from wearing insoles or an insulating floor.
In ATEX zones, where flammable gases, liquids and powders are frequently used, the electrostatic risk is particularly present.
If an electrostatic discharge occurs in an explosive atmosphere, ignition and/or explosion can occur.
The consequences ofstatic electricity and electrostatic hazards on materials and personnel must be understood.
How to prevent electrostatic hazards in explosive atmospheres?
Assessing electrostatic risk
A priori, the industrial risk assessment for an industrial or SEVESO site should enable us to estimate the risk of electrostatic discharge. This involves an audit – to be carried out by a certified body :
- Identify flammable atmospheres for each zone and assess the energy required to ignite them.
- Estimate the sensitivity of a flammable or explosive atmosphere to ignition. The sensitivity of an area to ignition is measured in EMI (minimum ignition energy).
- Quantify the energy of discharges that may occur, and estimate their different energy levels in different areas and situations.
- Compare the energy that can be released in the event of a discharge with the energy required to cause an explosion or ignition, depending on the zone.
- Study the ability of equipment and materials to retain or accumulate static electricity.
Mastering electrostatic phenomena
Once the electrostatic risk assessment has been completed, it is generally necessary to take additional protective measures in ATEX zones:
- Remove insulation products not required for industrial activities.
- Avoid electrostatic charging by using efficient earthing systems or equipotential bonding.
- Opt for anti-DES PPE: shoes, gloves, wristbands.
Do you want to minimize the impact of electrostatic hazards in ATEX zones?
ADF Systèmes makes it a point of honor to help you choose the products and solutions best suited to your industrial safety and risk management needs. To learn more about ESD risks, download our grounding guide.
