The risk of explosion is present in many sectors where hazardous substances are handled daily. These include flammable liquids such as paints or solvents and their vapours - but also explosive dust. Whether processing, transporting, or storing, the proper measures must be taken to protect employees and equipment.
Below, you will find out what you need to know about the explosion risks and how to protect your facilities and employees against them.
What are the common errors made when it comes to protecting against explosions in the workplace? Which guidelines and operator obligations must be taken into account? And what do you have to pay attention to when classifying the ex-zones? Bastian Bröhenhorst is a DENIOS expert on explosion protection and answers these questions.
Mr. Bröhenhorst, where are the uncertainties with respect to explosion protection?
The moment an explosion occurs, the potential consequences are devastating and can lead to death. This isn't very comforting for many people, often meaning they do not address the topic adequately and try to pass the responsibility onto someone else. This can be very dangerous, but there are enough guidelines, guides, and experts to guide people through this problem and ensure the proper measures are implemented.
How is an explosion created?
An explosion occurs when three components are present: oxygen, a flammable substance, and an ignition source. If a spark occurs and hits a mixture of oxygen and combustible material (gases or dust), it will explode. The prerequisite for an explosion is a suitable concentration of the substance. If too much oxygen is present and very little of the flammable substance, it will not explode because the concentration of the volatile substance is much too low. Alternatively, there is no explosion when the air is completely saturated with combustible matter, and no oxygen is present. This is described with lower and upper explosion limits. The mixing ratio can, therefore, be used to prevent an explosion.
Which directives must be taken into account for explosion protection?
The European community explosion protection directives (ATEX equipment directive 94/9/EC and ATEX workplace directive 1999/92/EC) oblige all persons, from suppliers to company management, to use corresponding best practice methods and equipment to protect the workforce.
As a manufacturer of products for use in areas with an explosive atmosphere, we are obliged to safely develop and market these products accordingly, and this is regulated by the ATEX equipment directive 2014/34/EU, which came into force to harmonize national regulations within the EU. Caution is required as products with a potential ignition source must be marked. As a result, ATEX is deeply rooted in our processes, especially when developing new products. We use several tried and tested templates and checklists to ensure right from the start that our products are suitable for use in potentially explosive atmospheres.
For the customer, the operator is responsible for avoiding or limiting the formation of explosive atmospheres, avoiding effective ignition sources, and limiting the effects of an explosion to a safe level. This is regulated by the ATEX company directive 1999/92 / EC. They are responsible for performing a risk assessment and putting the proper protective measures in place to protect workers from explosions.
What measures can be taken for explosion protection?
Three steps should be followed. The first step is to try to prevent the formation of an explosive atmosphere by controlling the ratio between oxygen and fuel. But this first step is the hardest and cannot always be guaranteed, as most companies store hazardous materials because they need them. This automatically creates an explosive atmosphere. You can, however, still ensure that the mixing ratio is changed by installing technical ventilation systems in your room system.
The next step would be to prevent the ignition source from becoming effective. If this cannot be achieved, the third step would be to control or limit the explosion to a safe level. An example here would be to install a pressure relief hatch. These pressure relief hatches are mounted on room systems' roofs, where no one can be harmed.
What do you have to consider when purchasing products for hazardous areas?
Labelling is essential. Firstly, there are three ex-zones: Zone 0, Zone 1 and Zone 2 and some products are designed for use in different zones. In addition, users sometimes think that products may only be used in potentially explosive areas if they have a label, which is not always the case. Only products that fall under the ATEX Directive are subject to labelling, which is when the products have a potential ignition source. If the product does not have this ignition source, it can be used in an Ex zone and does not require labelling.
What do you need to know about classify ex zones?
The environment around the explosive substance is divided into three different zones, spatially and in terms of time, considering any outgassing. Zone 0 is located directly in the hazardous area where there is a potentially explosive atmosphere; Zone 1 is located in the area around it, and Zone 2 is in the area around that. In addition, there is the temporal aspect to consider. To clarify, consider the example of a tanker with a petrol mixture on board. The highest concentration of the explosive atmosphere is inside the tank, above the surface of the liquid. Here it’s Zone 0. When the tank is unloaded, the direct vicinity of the pumping nozzle, or hose connection, is Zone 1. In this zone, the likelihood of a dangerous explosive atmosphere being created is lower. As the distance from the pumping nozzle increases, the substance's concentration and the probability of an explosive atmosphere get smaller, which is classified as Zone 2. Depending on the zone, various safety precautions must be taken to prevent explosions.
Essential products for safety in hazardous areas
We have it covered when it comes to explosion protection. Our vast range of products for use in potentially explosive areas covers all three levels of explosion protection, from extraction tables for removing hazardous fumes to non-sparking products that avoid effective ignition sources. In addition, if your ATEX assessment does not prevent an explosive atmosphere or prevent the complete avoidance of ignition sources, we will equip your hazardous goods warehouses with pressure relief flaps that limit explosions to a safe level.
Our expert team will happily advise you on the right solution for you.