If there is not ducted ventilation through the cabinet, the bungs (both of them), should remain in place. This will likely improve the temperature barrier properties of the unducted cabinet.  Unless, of course, the authority having jurisdiction requires otherwise.  Then you want those flame arrestors to remain in good condition.

If an existing cabinet is exhausted from the high bung rather than the low bung and you can accomplish it without undue difficulty or expense, I would correct the error.

Peter Zavon, CIH
Penfield, NY

PZAVON**At_Symbol_Here**Rochester.rr.com

Dear Listers,

Thanks in advance and pardon the cross-posting.

NFPA 30 states that IF flammable cabinets are ducted to the ventilation system that the supply be provided at the top and the exhaust be connected to the bottom. Presumably, this creates a downward directed cross draft that ensures removal of vapors with high vapor density from the bottom of the cabinet.

I have two questions:

1) if there is not a ducted supply does that supply bung stay open or closed?

2) if an existing cabinet is vented with the exhaust from the top should it be changed to vent from the bottom?

Many thanks,

Chris

Christopher E. Kohler, MS, LPG, CCHO

Laboratory Safety Manager, EHS

Laboratory Safety Instructor, ACS

Adjunct Faculty, SPEA

Environmental Health and Safety

1514 E Third Street

Bloomington, IN 47405

(812) 855-5454

cekohler**At_Symbol_Here**iu.edu