What to do when machinery safety & explosive atmospheres meet

However, there’s no room for complacency – explosions can still happen even with apparently benign processes including food ingredients such as flour and sugar – all technical equipment that is a potential ignition source can trigger an explosion under certain conditions which is why Euchner has launched an upgraded range of ATEX approved safety switches and interlocks for use on equipment within potentially hazardous manufacturing environments.

Conventional safety interlocks for monitoring or securing doors are generally not suitable within facilities where combustible materials, including gases, vapours, mist or dust could be present, while the common ATEX switch and locking solutions for these zones often fall short of the applicable machinery safety standards, including EN ISO 13849-1 and EN-ISO-14119.

ATEX equipment manufactured by Euchner is suitable for use in Zone 2 (gas) and Zone 22 (dust) environments with the recently developed Euchner CTP switch filling the gap between explosion protection and general machinery risk-reduction such as preventing personnel access to rotating equipment.

The ignitability of an explosive atmosphere depends on the material of course. Gases and vapours are classified into explosion groups IIA, IIB and IIC depending on the energy required for ignition. The ATEX CTP manufactured by Euchner belongs to explosion group IIC which includes extremely flammable gases such as Hydrogen and Acetylene. Dust materials are classified in a similar way, with explosion groups IIIA, IIIB and IIIC depending on the size and conductivity of the dust particles. All ATEX equipment manufactured by Euchner belongs to explosion group IIIC which even includes dust containing carbon.

In addition to its suitability for use in potentially explosive atmospheres, the ATEX CTP range also achieves Cat4/PLe in accordance with EN ISO 13849-1. An extra feature is the ability to ‘code’ the actuator to the switch thereby preventing possible manipulation or tampering of the safety circuit as highlighted within EN-ISO-14119. Because of the monitored guard-locking function, the CTP switch is suitable for applications with extended run-down times or even where an inert gas purge is required prior to operator or maintenance personnel access.

The robust housing makes the unit especially suited for harsh environments offering a high degree of ingress protection. Its compact design permits space-saving guard mounting with a locking force of up to 3900N. 

Hinged actuators make it possible to use the CTP locking solution on very small radii doors, while for applications where full body access is required Euchner also produces a variant with a manual escape-release system built in.

Joe Ardley, Euchner UK’s Technical Manager, said: “Protecting people from the dangers of work equipment can be especially difficult where potentially explosive gases and dusts are also present. The relevant parts of the EN 60079-XX standard must always be taken into account when selecting equipment and we are delighted to be able to offer a complete solution to ensure the safety of personnel from both potentially explosive and general machinery hazards.”

Euchner’s CTP ATEX series is just one of a comprehensive range of devices available from the company suitable for use within industries operating with potentially explosive atmospheres including defence, food, petrochemical, pharmaceutical, chemicals and waste-water.

http://www.euchner.co.uk