Pressurized enclosure in Cl1 div2-not req seal at the boundary

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99cris

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1. At a duct burner purged enclosure in a Power Plant the exit L fittings should be explosion proof.

I do not agree w/this statement, because as per NEC-2005
501.15B2(Exception 3): "Conduit systems from an enclosure or room that is unclassified as a result of pressurization into Cl1 Div2 location shall NOT require a seal at the boundary"

Also the enclosure is Type Z which is satisfying the requirements in NFPA-496 art 4.8.3 for
alarms and 4.8.1 for detection of low pressure etc.Am I right?

2. The enclosure is NEMA4 and the pressure system is UL...Does this combination make the hole system (Enclosure and system) complying with NEC-110.3 regarding use as intended? I cant imagine UL-ing the pressure system without an enclosure.
 
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99cris said:
1. At a duct burner purged enclosure in a Power Plant the exit L fittings should be explosion proof.

I do not agree w/this statement, because as per NEC-2005
501.15B2(Exception 3): "Conduit systems from an enclosure or room that is unclassified as a result of pressurization into Cl1 Div2 location shall NOT require a seal at the boundary"

Also the enclosure is Type Z which is satisfying the requirements in NFPA-496 art 4.8.3 for
alarms and 4.8.1 for detection of low pressure etc.Am I right?

2. The enclosure is NEMA4 and the pressure system is UL...Does this combination make the hole system (Enclosure and system) complying with NEC-110.3 regarding use as intended? I cant imagine UL-ing the pressure system without an enclosure.
Click to expand...

I don't know what a duct burner is but if it is utilizes either an open flame or suface teperatures at or above AIT classification of the area would nto be required.

The only time and XP seal would be required at a purged entry if the seal fitting is to contain the potential explosion traveling from the hazardous side. That is of course unlikely.

However you can see seals mistakenly applied on the purged enclosure because people fail to differentiate between XP seal and seal provided to conserve the pressurizing air or inert gas that used for the purging and inerting gas to facilitate the type Z purge.
 
Pressurized enclosure in Cl1 div2-not req seal at the boundary

Thanks for replaying....

What do you mean by "seal provided to conserve..." a dedicated UL listed seal or a COX sealing material at the boundary inside and outside of L connection?
 
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