Explosive atmospheres are a significant risk to people and property in a variety of industries such as petro-chemical, food processing, recycling and mining
In order to maintain a high level of safety and explosion protection, global regulations, standards and legislation have been developed through the International Electrical Committee (IEC) . For the European Union, these IEC Explosion (Ex) regulations have been compiled into the ATEX Directive.
A potentially explosive atmosphere (also called a hazardous zone) exists where combustible gasses, dust, mist and vapors are at risk of forming an explosion due to the combined presence of oxygen and an ignition source. Ignition sources could be any of a large number of triggers such as:
In order to protect installations from a potential explosion it is important to analyze and classify different hazardous zones. As such, the most appropriate equipment can be selected to ultimately prevent or contain an explosion. A hazardous zone is defined by three criteria:
ATEX (explosion protection) certification is a process that ensures that equipment and protective systems designed for use in potentially explosive atmospheres meet the required regulations, standards and directives. Manufacturers in the European Union, have to certify that their products will not cause an explosion during routine operation in potentially explosive atmospheres. It covers essential health and safety measures for:
Note that ATEX standards may also apply to safety, controlling or regulating devices that are required to avoid explosions, even if these devices are placed outside of the potentially explosive atmosphere. It is for this reason that we at Kamet have ensured we can supply various ATEX certified or ATEX ready components and sensors (e.g. cable, sensors, connection heads and instrument housings).
The ATEX directive recognises two types of ATEX atmospheres:
The following table summarizes the zones. :
|Flammable Material||Present Continuously||Present Intermittently||Present Abnormally|
|Gas/vapor/mist||Zone 0||Zone 1||Zone 2|
|Combustible Dust/Fibers||Zone 20||Zone 21||Zone 22|
|Suitable Explosion Protection Type*||Ex ia||Ex d, Ex e or Ex m||Ex m or Ex n|
*It is always possible to use a higher rated Protection Type than necessary for a particular Zone.
In order to ensure the potential for an explosion is removed or significantly reduced, a variety of approaches can be used. These include:
ATEX codes indicate the type of protection method for which equipment has been certified. This code consists of an Ex (explosion) followed by a letter. Here is a brief overview of some of the most common letters:
Explosion protection is a vast subject matter, well beyond the scope of this article. We include it here in our knowledge base because Kamet’s temperature sensing components have an important role to play in measuring and transmitting accurate temperature readings in potentially explosive environments. They are used both in the application’s equipment and atmosphere to make sure maximum and minimum temperatures are not being exceeded at any point.
At Kamet we can help you with choosing the correct components to ensure your process is ATEX compliant. The Kamet team is happy to answer any questions you might have in this regard. You can contact us here.
More about selecting temperature sensors for potentially explosive (Ex) atmospheres, can be found here.