+31 314 373 333Since 1 July 2003, every organization in the European Union has had to comply with the ATEX 153 (99/92/EC) workplace directive, to create safe working conditions for employees. As part of that, the ATEX 114 (2014/34/EU) equipment directive applies in the European Union to any equipment (electrical and non-electrical and including protective systems) intended to be used in places where an explosion can occur. At Hosokawa Micron, we help our customers with both new and existing mixing, drying and agglomeration equipment to ensure their Hosokawa Micron equipment complies with the latest ATEX directives.
How does an explosion occur?
For a fire or explosion to occur, three elements must be present at the same time and place:
- Fuel (gas, vapour or dust)
- Oxidant (air)
- Ignition source
These elements are often depicted in the so-called 'fire triangle'. An explosion results when the fuel and oxidant are mixed in the right proportions and the mixture is confined. According to the European standard for the identification and assessment of hazardous situations leading to an explosion (EN1127-1), there are 13 different types of ignition possible. Static electricity is the most common trigger of explosions in manufacturing environments, and it is particularly dangerous because – unlike cables or wires – you can't see it beforehand. An electrostatic charge can build up when a fine powder is mechanically agitated, such as in a mixing process, or as it flows through pipes. If the pipes are made of metal, the energy will be discharged again fairly quickly. But plastic is an insulator, so synthetic pipes can result in highly charged combustible dust clouds forming in the mixing chamber, for example. These can then explode if a static discharge occurs. The consequences can be dramatic and even fatal. A study in the United Kingdom and the Netherlands has shown that, on average, a dust explosion occurs once a week, and 20% of the cases result in major injuries.
Unique product properties
The risk of explosion is higher than many people realize, even in the case of seemingly 'innocent' products. They tend to think of high-risk sectors, such as the chemical industry, or of explosions being triggered by faulty wiring or a fire. But various types of powders can form combustible dust clouds. The severity of an industrial explosion depends on a number of factors, such as the flammability and combustibility of the products being processed. Every product has its own unique properties. Sand doesn't burn easily, for example, whereas a product such as milk powder is highly flammable. As a general rule, all organic dusts and gases can form an explosive atmosphere together with an oxidizing agent (mostly in air), so in the case of our customers that includes starches and sugars as well as various chemicals, plastics and metals. The particle size of the product also plays a role; smaller particles pose a greater hazard because a relatively bigger surface area is exposed to the air. And in the case of milk powder, for example, the granules are encapsulated in a layer of fat which makes them very quick to burn.
Not just dust explosions
Dust explosions are not the only risk in powder handling systems. Mixing or heating certain types of products, such as a powder in combination with a liquid or solvent, can cause the formation of explosive gases, for example. In the confectionery industry, alcohol is sometimes mixed with flavourings to achieve better distribution. The alcohol is then evaporated out of the product, but the vapours can remain in the machine and pose an explosion risk. Alcohol is also widely used for cleaning purposes, of course, such as in the pharma industry. So at Hosokawa, we make companies aware that potentially hazardous situations can occur during the cleaning process as well, depending on how the detergents or solvents react with the actual products in the equipment.
Hazard zones
Under the ATEX workplace directive, customers themselves are responsible for ensuring they continue to comply with the regulations. They are required to classify production areas into 'zones' depending on the type of hazard (a gas/vapour/mist explosion or a powder/dust explosion) and the likelihood of an explosive atmosphere occurring. Whenever Hosokawa Micron supplies new equipment in the EU, the customer is obliged by law to specify whether the equipment is intended for use in a hazardous environment. If so, Hosokawa Micron supplies the parts and/or equipment according to the specified ATEX zone. Based on our specialist knowledge, we build Hosokawa Micron equipment to prevent the formation of an ignition source. We have identified the main inherent ignition sources for our equipment as being hot surfaces, mechanically induced sparks and static discharges. By addressing these possible ignition sources from the design phase, throughout production and during installation, we are able to ensure our equipment complies with the ATEX 114 directive.
Material flow
In the case of existing machinery, however, it is the customer's own responsibility to assess and deal with potential hazards – but there are many factors and possible solutions to consider, leaving many customers feeling out of their depth. There are numerous consultancy firms that offer ATEX advice, but they tend to look at the overall production environment rather than also at what actually goes on inside the machinery and how the materials flow from one piece of equipment to the next. We can analyse the Hosokawa Micron equipment currently in use to help the customer reduce the explosion risk to an acceptable level based on the specific situation and the customer's preferences. If the outcome reveals static electricity, for example, we will suggest solutions, such as to change the product intake or modify the equipment – without affecting operational efficiency and end-product quality, of course. Other solutions, depending on the type of product, could be to attach an earthing device, regulator or sensor inside the pipes, burst plates or to create an inert atmosphere in the mixing chamber.
Modular systems
The situation is even more complex in the case of modular systems that companies have assembled themselves, as well as older systems. The ATEX equipment directive applies at several different levels – not only to the machine itself but also to its components, plus to the overall production set-up. Things can get very complicated if a customer replaces an electromotor or even a switch in a batch mixing system, for example. If you replace an existing component with one that doesn't have the right ATEX certification, or if you connect two ATEX-compliant components together using a plastic pipe that isn't ATEX certified, there's no guarantee that your production system as a whole is still ATEX compliant. In line with our 'total solution' approach at Hosokawa, we combine our customers' understanding of the product properties with our own knowledge of the equipment to decide on the right safety measures for each specific set-up as a whole.
Employee safety is top priority
Besides this, the regulations are changing and evolving all the time. This means that the standards initially used to certify an existing machine could now be outdated, in which case it's the customer's responsibility to implement the necessary extra safety measures. At Hosokawa, our experts continuously monitor and interpret the changes so that we can advise our customers on which steps they need to take. We identify how their equipment can be modernized if necessary to minimize the explosion risk based on their particular products and process requirements. So as powder-processing specialists, we work closely with each customer to ensure that their Hosokawa Micron mixing, drying and agglomeration machinery – whether new or existing – meets the requirements of the ATEX 114 (2014/34/EU) directive. After all, employee safety is the top priority because everybody wants to go home safely at the end of each day.
