ATEX class T3

[Charbel]

dear,

there will instruments to be installed for fuel system in KSA where the maximum outdoor ambient temperature reaches 85C without sunshade.

The instruments are specified as class T3 where the maximum surface temperature can be up to 200 degree C.

Supplier is giving instruments satisfiying 85C as class T6.... my question, is this acceptable? i mean the supplied instruments are specified as working for the maximum outdoor temperature which is 85 degree C.

shall i accept them or stick to the requirement of class T3 (max=200 degree C).
I want to understand is the specified maximum temperture from Atex as T3, does it mean that the instruments will be still functional even an explosion has occured making the temperature reach 200 degree C?

thanks for your clarifications.

 

[Manglemender]

The "T" rating is not a working temperature rating but a maximum temperature that the device will reach on its own. N.B. This is normally a rated for an ambient temperature of 20C. The working temperature range is not necesarily the same as the "T" rating.

You may find this chart helpful: http://www.siracertification.com/UserDocs/DSEAR%20technical%20datasheets/CSA%20Sira%20wallchart%202013.pdf

Nick

 

[Charbel]

Dear Nick,

thank you for your reply.

refering to the below:

"The "T" rating is not a working temperature rating but a maximum temperature that the device will reach on its own"

how does what you say reflect for example on a GWR level transmitter.
Maximum surface temperature that can be reached will be 200C due to the ignition of the gas? i mean the material made by the GWR level should be changed to whithstand this temperature?

What i need to know if it is acceptable to use any instrument (GWR, non-contact radar, pressure transmitter) if the instrument is rated for maximum ambient temperature of 85 degree C and Class T6 instead of the requirement of maximum ambient temperature of 85 degree C and Class T3.

thank you!

 

[Manglemender]

Sorry for any confusion. Flamable gases are given a temperature class rating based on their auto-ignition temperature. Equipment for use in the presence of flamable gases is also given a temperature class rating based on the maximum surface temperature that the device will reach.

For example: Kerosene has a T3 rating and so devices used in the presence of kerosene must be certified T3 or better (T4, T5, T6).

This link may explain it better: http://www.atex.info/a/hazArea/tempClass.php

The consequences of getting this wrong can be catastrophic. I would reccommend consulting an expert if you are unfamilliar with ATEX requirements.

Nick

 

[Charbel]

Dear Nick,

thank you, it is clear now.