purged cabinet class II div 2 ambient temperature -20°F to 104°F

Hi colleagues and Ex specialists,
I'm an engineer and need to plan a purged cabinet for use I Class II Division 2 area.

The cabinet is pressurized with bebco system.
So my problem is the equipment in the cabinet, it can only start at a inside temperature of 32°F.
Because of the deep temperature I chose a cabinet heater from Hoffman with integrated adjustable thermostat.
Heater is not Ex, because I believe after cleaning and closing the cabinet I can use normal execution of a heater.
An additional mounted non Ex thermostat (Stego) e.g. adjusted to +41°F will switch power to the equipment on the backplane.

Hoffman told me maximum surface temperature of the heater is 140°C.
In my opinion this will work.
But in case of opening the door e.g. some dust will invade through the cooling slots of the heater.
Has this to be considered in Division 2?

I`m grateful for any comment.
.
Best regards
 
It is a big cabinet 78"x40"x23".
Need to install an overpressure with bebco (P+F) for class II prge system (1001).
I believe I cannot protect the inside equipment with another solution.
Best regards
Thomas:?
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
It is a big cabinet 78"x40"x23".
Need to install an overpressure with bebco (P+F) for class II prge system (1001).
I believe I cannot protect the inside equipment with another solution.
Best regards
Thomas:?
I think you should take a close look at what article 502 says about what components are allowed to be used in a CIID2 area.
 

rbalex

Moderator
Staff member
It is a big cabinet 78"x40"x23".
Need to install an overpressure with bebco (P+F) for class II prge system (1001).
I believe I cannot protect the inside equipment with another solution.
Best regards
Thomas:?
A word of caution: With respect to a 'Type "Ex p" (purged/pressurized)' protection technique, do not attempt to apply IEC/CENELEC/EN (etc.) Zone 22 concepts to NEC Class II, Division 2 - or even NEC Zone 22 (Article 506). [The NEC modifications to IEC Zones are a bizarre "force fit" into NEC Divisions.]

As petersonra suggested see Article 502. I also suggest you become very familiar with NEC Articles 500 and 506 and NFPA Standard 496.
 

ras

Member
Location
buford, ga 30518
What you can do is call P&F direct and speak with someone in their technical dept. for some free advice. Explain what you are trying to achieve they are very helpful and very knowledgeable.
 
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