Fire/smoke damper required?

[ajerold]

We have an exhaust duct penetrating a fire partition wall equipped with a combination fire/smoke damper. The problem is that the equipment we are exhausting generates smoke which triggers the smoke damper everytime it's on. We can't reroute the duct to miss the fire wall so we are pretty much set with the location. Does anyone know if there any exceptions to code regarding this? The project is located in California.

Thanks in advance

 

[Drazen]

Fire walls need fire dampers with no exception, while the fact that smoke damper is needed should mean that the same wall is defined as smoke bareer.

That is part you can check in building documents as fire wall is not necessarily smoke bareer.

Smoke bareer also does not have to have full fire rating, so you can possibly move damper elsewhere if it is intended to protect some specific space from smoke intrusion.

 

[cdxx139]

If it is a dedicated system, depending on your code, smoke damper should not be required since you are not open to any other floor(no chance for smoke migration).

If you ganged hoods on multiple floors, then...

Local code here, allows subducts w 24/7 exhaust as an alternative to a smoke damper.

You may still be able to add them. It will add pressure drop to the current system, but if the motor is over sized, it should be able to compensate.

To remove the fire damper requirement you could have used firewrap.

knowledge is power

 

[kashain]

You may fire rated the duct without providing fire smaoke damper.

 

[marcoh]

Or delete the fire/smoke damper and fire spray the duct

 

[317069]

In my knowledge, the NFPA 96 says:
9.1.1 Dampers shall not be installed in exhaust ducts or exhaust duct systems.

 

[mauricestoker]

I think the answer might be in part related to what equipment you are exhausting and how the rest of the facility's smoke protection is designed. Is this wet lab, an emergency generator, a commercial kitchen? Depending on what the equipment is (and perhaps the design basis for fire/smoke protection-NFPA 45, NFPA 90A, NFPA 92A/B, etc.) a damper may or may not be allowed by national code.

 

[tys90]

317069, that applies to commercial kitchens. In fact, in commercial kitchens you can't put dampers in exhaust duct OR pass the duct through a fire wall.

It really depends on the application as others have said.

 

[stookeyfpe]

It would be helpful to know the applicable code since the IMC is in a number of cases more restrictive than NFPA 96. Since NFPA 96 was mentioned by someone, dampers are prohibited in Type I hood mechanical exhaust systems by the IMC.

 

[317069]

is there a different between fire wall and fire barrier?

 

[ChrisConley]

Usually the number of hours: 1, 2 hours = fire barrier(or fire separation) 4 hours or more = fire wall.

 

[317069]

Some definitions from NFPA96
3.3.20 Duct(or duct system): "A continuous passageway for the transmission of air and vapors that, in addition to the containment component themselves, might include duct fittings, dampers plenums, and/or other items or air handling equipment."

note: we could consider that the definition above apply to exhasut duct system regardless what is the application.

3.3.26 Fire wall: a wall separating buildings or subdividing a building to prevent the spread of the fire and having a fire resistance rating and structural stability.

there is no a definition for fire barrier

7.1.1 says: Ducts shall not pass through fire walls
7.7.1.2 says: in all buildings where vertical fire barriers are penetrated, the duct shall be enclosed in a continuous enclosure extending from the first penetrated fire barrier....etc"

it is little confuse
if we back to the question, he says that they have a duct is penetrating a fire wall equipped with fire/smoke dampers.
how they have built this project from the first, they know they have a smoke damper and sure they know what equipment to be exhausted they have.

 

[houseman20]

There are many systems that are prohibited from having fire dampers or smoke dampers. clothes dryer exhaust, kitchen exhaust, hazardous exhaust, stair pressurization, smoke control system, etc. Generally, you would enclose these systems in a 2hr rated wrap.

 

[cry22]

It is IBC (UBC for CA) that applies, not NFPA or IMC
Smoke dampers are not required when part of a smoke control system (in life safety systems), I'd say this is your application, except for your case, it is "process" requirement, not life safety requirement.
You need to look at an "engineered control system", eliminate the smoke dampers which hinder your process, install a motorized damper that would be triggered by say activation of fire suppresion system, space heat detector or something like that.

Fire wall or fire barrier is irrelevent, you can penetrate with a duct if part of an "engineered control system" (exception in IBC).

What you cannot penetrate is a rated wall that is used as a building separation wall between two buildings.