Mechanical measuring instruments for use in explosive atmospheres can now be evaluated in accordance with a new standard: DIN EN ISO 80079-36/37 will replace EN 13463-1/5, with the transition period ending on 31 October 2019. For the first instruments, WIKA has classified the model 73 and model 74 gas-actuated thermometers in accordance with the new directive and has issued the corresponding declaration of conformity. What does this change mean for the user?

Firstly, and most importantly, the internationally valid ISO 80079 (date of application: 01 December 2016) has taken over the basic safety requirements of EN 13463. Both of the gas-actuated thermometers evaluated by WIKA therefore remain constructionally and functionally unchanged.

The most obvious difference is the marking of the instruments. The information on the dial and the product label correspond to the requirements of both ISO 80079 and those of the new ATEX directive, 2014/34/EU:

ATEX 2014/34/EU
ISO 80079-36/37
A B C D E 1 2 3 4 5 6
II 2 G Ex h IIC T6 … T1 Gb X
II 2 D Ex h IIIC T85°C … T450°C Db X

For the user, the note on the type of protection is of particular interest – the letter “h” certifies that the mechanical instrument has the basic suitability for use in explosive atmospheres. The previous conventional information on the ignition protection type “c” (protection through constructive safety) is no longer required. However, the criteria for the fulfilment of these and other types of protection are also included in the new standard, and WIKA has, as before, followed the requirements for ignition protection type “c” in the current conformity assessment.

The new marking is explained in detail in the following tables:

ATEX 2014/34/EU

 ID Marking Sign Meaning
 A CE marking Communautés Européennes / European communities
 B Specific marking for explosion protection  
 C Equipment group II Equipment intended for use in other places than underground parts of mines, and in those parts of surface installations of such mines, liable to be endangered by firedamp and/or combustible dust and also through an explosive atmosphere.
 D Instrument category 2 High safety (approved for zone 1 and 21)
 E Ex atmosphäre  G Suitable for areas in which explosive gas, vapour, mist and air mixtures are present.
D Suitable for areas in which explosive atmospheres caused by dust can form.

ISO 80079-36/37

 ID Marking Sign Meaning
 1 Ex marking  Ex Per ISO80079-36/37
 2  Type of protection h Non-electrical equipment for explosive atmospheres
 3  Suitable atmosphere IIC Gas (group IIC)
IIIC Combustible suspended solids, conductive dust and non-conductive dust
 4 Maximum surface temperature* T6 … T1 Temperature class
T85°C … T450°C Max. surface temperature
 5 EPL (new: Explosion Protection Level) Gb Protection from ignition sources that are effective or may become effective during normal operation and expected malfunction.
 6 Special application conditions (see instruction manual) X Ambient temperature with special range (here special operating conditions apply)
  * The actual maximum surface temperature depends not on the equipment itself, but mainly on the operating conditions.

Further information on the model 73 and model 74 gas-actuated thermometers and also the corresponding declaration of conformity can be found on the WIKA website.

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