Flexible tubing crossing Hazardous Area to safe area

[luisschwartz]

Hello,

I have an application where my diff Press transducers will be located in the safe area and tubing to be ran into a C1D2 area. Does my transmitters in the safe area need to be Ex protected (IS)?

If yes, can you share the explanation as to why and the code it falls under?

thanks in advance

 

[petersonra]

Are you bringing something flammable from the classified area to the unclassified area via the sense lines?

 

[rbalex]

“Flexible tubing” is simply not a recognized wiring method in Class I, Division 2. [See Section 501.10(B)(1)]

That said, peterdora’s question in Post #2 above is extremely relevant. [See Section 501.15(B)(2)]

 

[petersonra]

“Flexible tubing” is simply not a recognized wiring method in Class I, Division 2. [See Section 501.10(B)(1)]

I think the flexible tubing he mentioned is for the dp sense lines, not wiring.

 

[luisschwartz]

Are you bringing something flammable from the classified area to the unclassified area via the sense lines?

Yes, EtO (Ethylene Oxide) flammable at room temperature

 

[luisschwartz]

“Flexible tubing” is simply not a recognized wiring method in Class I, Division 2. [See Section 501.10(B)(1)]

That said, peterdora’s question in Post #2 above is extremely relevant. [See Section 501.15(B)(2)]

I'm referring to tubing (gas transport) sense line

 

[luisschwartz]

I think the flexible tubing he mentioned is for the dp sense lines, not wiring.

correct

 

[luisschwartz]

the hazardous area is classified as C1D2 and under vacuum @ -0.007 wc. The safe area is ambient pressure.
The DP is to be located on the safe area
Does my DP need to be Ex protected (IS)?
Would it be viable if the sense line (tubing) breaks the hazardous atmosphere gets transferred to the safe area (considering the hazardous area is under minimal vacuum)?
thanks everyone

 

[rbalex]

I think the flexible tubing he mentioned is for the dp sense lines, not wiring.

Thanks for the correction. I misread the post. The NEC doesn’t say anything with respect to the question. Your point was still well taken.

 

[luisschwartz]

anyone?

 

[rbalex]

As I mentioned, the NEC doesn’t speak to your issue. The two dominant Standards for classifying most locations, NFPA 497 and API RP 500, don’t either. NEC Articles 511 to 517 do give some classification directives but are application specific and shed no light on your question.

“Ex” is technically an IEC (Zone) reference similar to Article 504. They don’t speak to your issue either.

In theory, an Intrinsically Safe (IS) or Noninsendive (NI) installation still has “boundary” issues. Not so serious for Division 2 but still needs attention.

In my opinion, the boundary issue is still the major concern. If there is reason to believe hazardous materials could migrate to the unclassified location through the tubing, the installation should be compliant with ANSI/ISA RP 12.06.01 or ANSI UL121201.