hvac duct firestopping

[brians76]

can anyone point me at info on firestopping for hvac ducts? i have (1) 24x36" and (1) 30x48" opening, each in a 6" concrete wall...both ducts wil have f/s dampers, but i am looking for an appropriate firestopping detail.

thanks!
brian

 

[MintJulep]

a Google search for "intumescent putty" returns lots of hits.

 

[imok2]

Brian,
Smoke dampers should be classified and listed in accordance with UL Standard 555S for temperature, leakage, and operating velocity. The velocity rating of a smoke damper is the velocity at which the actuator will open and close the damper.
At locations requiring both smoke and fire dampers, combination dampers meeting the requirements of both UL Standard 555 and UL Standard 555S can be used. The combination fire/smoke dampers must close when they reach their UL Standard 555S temperature
rating to maintain the integrity of the firewall. Fire, ceiling, and smoke dampers should be installed in accordance
with the manufacturers’ instructions. NFPA Standard 90A gives general guidelines regarding locations requiring these dampers.
The supply and return/smoke dampers should be a minimum of Class II leakage at 250°F. The return air damper should be a minimum of Class I leakage at 250°F to prevent recirculation of smoke exhaust. The operating velocity of the dampers should be evaluated when the dampers are in smoke control mode. To minimize velocity
buildup, only zones adjacent to the fire need to be pressurized. floor, a pressurized stairwell must maintain a positive pressure difference across a closed stairwell door to prevent smoke infiltration. Anyway try this for more info

http://www.greenheck.com/products/dampers/smoke.html

 

[jherbert]

hi,

I would strongly suggestion that one contacts
the f/s damper manufacturer. They will have
approved installation detail, which should
comply with the relevant building and fire
codes per your jurisdiction requirements.

cheers,