NFPA 90A and Smoke Dampers

[Pmatherne]

I am laying out a school that has a lot of smoke rated partitions. I am trying to use Figure A.5.3 as a go-by to figure out where to place the smoke dampers for the return air path and I am coming up with a large amount of dampers. Does anyone know of a resource I can use to back check myself
Mainly I am looking for information about the return air trunk duct that does cross through smoke rated partitions, sometimes it picks up return air from rooms and other times it passes just through the partition.

 

[tys90]

I don't mean to question you but are you certain these are smoke BARRIERS and not smoke partitions or a wall "capable of resisting the passage of smoke" (a term the IBC uses that is neither a smoke barrier or a smoke partition)? Smoke barriers encompass an entire smoke compartment. If you are crossing these boundaries frequently I suggest getting with the architect and figure something new out or split up your air handling units so they only serve the smoke compartment they are contained in.

If they are smoke partitions and not barriers, you do not need dampers for ducted systems under NFPA 90A and IBC 2009. Note that IBC will still require a smoke damper for transfer ducts.

As always, this is just for the local codes I am familiar with, consult your local authority and codes.