The risk of explosion is present in many sectors where hazardous substances are handled on a daily basis. These include flammable liquids such as paints or solvents as well as their vapours - but also flammable dusts. Whether processing, transporting or storing, the right measures must be taken to protect employees and equipment.
Below you will find out what you need to know about the risks of explosion 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 is frightening for a lot of people, which often means they do not address the topic properly and try to pass the responsibility onto someone else. This can therefore me be very dangerous, but there are enough guidelines, guides and experts to guide people through this problem and ensure the right measures are put in place.
How is an explosion created?
An explosion occurs when there are three components present: oxygen, a flammable substance and an ignition source. If a spark occurs and hits a mixture of oxygen and combustible material (gases or dusts), 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 flammable substance is much too low. Alternatively, when the air is completely saturated with the combustible matter and no oxygen is present, there is no explosion. 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?
Both of 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 practise 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 harmonise national regulations within the EU. Caution is required as products with a potential source of ignition need to be marked and as a result, ATEX is deeply rooted in our processes, especially when developing new products. We use a number of 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 sources of ignition and limiting the effects of any explosion to a safe level and this is regulated by the ATEX company directive 1999/92 / EC. It is their responsibility to perform a risk assessment and put the right protective measures in place to protect workers from explosions.
What measures can be taken for explosion protection?
There are three steps that 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 becoming effective. If this cannot be achieved, the third step would be to control or limit the explosion to an safe level. An example here would be to install a pressure relief hatch. These pressure relief hatches are mounted on the roofs of room systems, where usually no one can be harmed.
What do you have to consider when purchasing products for hazardous areas?
Labelling is very important. 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 and that is not always the case. Only products that fall under the ATEX Directive are subject to labelling and this is among other things, when the products have a potential source of ignition. If the product does not have this ignition source, then it can bu used in an Ex zone and does not require labelling.
What do you need to know about classify ex zones?
The environment around the combustible substance is divided into three different zones, both spatially and in terms of time, taking into consideration 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 located 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. Inside the tank, above the surface of the liquid is the highest concentration explosive atmosphere. 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 concentration of the substance and also the likelihood of an explosive atmosphere being created gets smaller, so this 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 huge range of products for use in potentially explosive areas covers all 3 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 sources of ignition, we will equip your hazardous goods warehouses with pressure relief flaps that limit explosions to a safe level.
Our expert team will be happy to advise you on the right solution for you.
The specialist information on this page has been compiled carefully and to the best of our knowledge and belief. Nevertheless, DENIOS Ltd cannot assume any warranty or liability of any kind, whether in contract, tort or otherwise, for the topicality, completeness and correctness either towards the reader or towards third parties. The use of the information and content for your own or third party purposes is therefore at your own risk. In any case, please observe the locally and currently applicable legislation.