Pressurized Air System for Class 1 Div 2 Location

[hou628]

Is there an NFPA requirement for a purged air system in a Class 1 Div 2 panel? I am installing an outdoor panel in an areas normally without hazardous air and am considering using a Type Z system. I am receiving pressure to reduce costs and am reviewing all costs for savings.

 

[hou628]

Reviewing NEC 501 now...

 

[Strathead]

Is there an NFPA requirement for a purged air system in a Class 1 Div 2 panel? I am installing an outdoor panel in an areas normally without hazardous air and am considering using a Type Z system. I am receiving pressure to reduce costs and am reviewing all costs for savings.

If I understand the question correctly, positive pressure inside an enclosure to prevent the build up of gasses during normal operation is one of the methods of reducing the classification from Division 1 to division 2. The distinction between the two classifications for this purpose is that in Div 1 explosive gasses in the proper mixture with oxygen are present during normal operation (a paint booth) division 2 gasses are only present do to an abnormal condition (a relief valve pops off or the area is pressurized so a failure of the pressurization would be required).

 

[petersonra]

Is there an NFPA requirement for a purged air system in a Class 1 Div 2 panel? I am installing an outdoor panel in an areas normally without hazardous air and am considering using a Type Z system. I am receiving pressure to reduce costs and am reviewing all costs for savings.

There is no requirement to use pressurization at all. There are other protections means that can be used. A type X purge is just one of the ways you can prevent ignition of flammable gases that might become present.

 

[fifty60]

Is type X purge an accepted method for making a Class 1 Div 2 location unclassified? NEC says that purging make Class 1 Div 1 unclassified, but it does not clarify if the same is true for class 1 Div 2..

 

[rbalex]

It's fine; it's just a big waste of money. Any protection techniques acceptable in Division 1 are acceptable in Division 2. You need to read NFPA 496.