Explosion protection in pressure measurement technology

ATEX BackgroundKELLER AG für Druckmesstechnik provides some advice on pressure measurement technology for potentially explosive environments

Explosions can be violent and tend to leave behind a great deal of damage. With this in mind, the ultimate aim when building electronic devices for use in potentially explosive environments is to completely prevent explosions. KELLER AG für Druckmesstechnik has been producing products for use in explosive environments since 1988. These certified products ensure safe operation in the most diverse range of use cases. 

What causes explosions? 

An explosion is a sudden chemical reaction involving an inflammable substance in the form of gas, dust, vapour or mist combining with oxygen and releasing large amounts of energy. This leads to an explosive atmosphere if the mixture achieves a very specific concentration ratio. If the concentration is too high (rich mixture) or too low (lean mixture), then a steady combustion reaction will occur, but no explosion. The mixture will only behave explosively on ignition if it is between the upper and lower explosive limit. The environmental pressure and the proportion of oxygen in the air influence the limits of the explosive atmosphere. 

Intrinsically safe pressure measurement technology by KELLER In addition to type d (flameproof enclosure) and type ec (increased safety) ignition protection products, KELLER AG für Druckmesstechnik mainly produces pressure transmitters, level probes and digital gauges of the ignition protection type i (intrinsic safety). Products certified to be intrinsically safe limit the energy so that ignition of an explosive atmosphere cannot be triggered either by sparks or thermal effects. KELLER is an international company and as such is not only limited to the European market. For this reason, the manufacturer of pressure measurement technology offers a wide range of certifications which can be applied to customer-specific products worldwide. 

Explosion-proof products in use 

Products that are suitable for potentially explosive environments have a very wide field of use. KELLER AG has been producing explosion-proof pressure measurement technology since 1988. As a result of this invaluable experience, KELLER’s certified products are recognised across many sectors. 

Measuring and transmitting 

If the products are being used in difficult-to-reach places, the measured data cannot always be processed on site. In cases such as this, KELLER also offers remote transmission units which forward the measured values to a server or the cloud. The recorded and measured data is lastly retrieved and evaluated via a customer application or via KELLER’s own KOLIBRI Cloud portal. Remote transmission units, such as the Box ARC1-SB made by KELLER, are in and of themselves not explosion-proof. Modules used in potentially explosive environments must therefore, as a matter of necessity, be installed outside of the explosive atmosphere. Remote transmission units for certified explosion-proof products contain safety barriers that limit the electrical power delivered to the connected intrinsically safe product. Ignition is prevented from occurring by this barrier and the required explosion preotection is achieved. 

Explosion protection of the future 

KELLER is currently developing a new type of radio transmission unit which communicates over LoRaWAN or NB-IoT networks (Internet of Things) and can also be installed within potentially explosive environments. This development will make explosion protection even safer, while simplifying the installation of pressure measurement technology in hazardous areas.


Alain Charles Publishing, University House, 11-13 Lower Grosvenor Place, London, SW1W 0EX, UK
T: +44 20 7834 7676, F: +44 20 7973 0076, W: www.alaincharles.com

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