FD vs FSD
FD vs FSD
(OP)
I've been taught to use a rule of thumb of calling for fire dampers in ductwork penetrating walls with a 1-hr fire rating; and calling for combination fire-smoke dampers in ductwork penetrating walls with a 2-hr fire rating.
The problem is that I have no idea where this rule of thumb came from. Has anyone else encountered this? Or better yet, know where this comes from?
The problem is that I have no idea where this rule of thumb came from. Has anyone else encountered this? Or better yet, know where this comes from?





RE: FD vs FSD
Here, International Mechancial Code IMC 2009 Section 607 rules. NFPA 90A-19 Figure A.5.3 is a nice pictoral, but doesnt include all updated building code requirements.
knowledge is power
RE: FD vs FSD
There is no code or standard where it is simply laid out saying a 1hr wall requires FD and a 2hr wall requires FSD. Am I wrong in believing that the rule of thumb is flawed? And yet, it seems to be very popular.
RE: FD vs FSD
As for the other 20%...in some cases, if it is a one hour partition, but the duct is just running through the space and does not have an opening to the space, then you dont need a fire damper.
Now you need a combination smoke fire damper any time you come out of a shaft. There ia an exception that allows a stainless steel subduct to exempt the fire damper, and if the unit runs 24/7, then you can exempt the smoke damper.
Codes are not written to be quick rules of thumbs, because then how would they fill in the 6" binders they come in? They are written to be difficult to read, so the Authority Having Jurisdiction can interpret it how he sees fit on that day. (I've been burnt in the past)
knowledge is power
RE: FD vs FSD
RE: FD vs FSD
RE: FD vs FSD
Also needed in RA at each floor at RA shaft.