Fire damper in duct through wall yes or no

[hollandhvac]

My design contractor says, he does not need to put a fire damper in a duct that goes through a fire rated walL when the size of the duct is 160mm in diameter or smaller?
What is your opinion?

 

[tys90]

Well, depends on the code you are under but there could be a few different parts of the code he's referring to. I'm guessing you are under the IBC of some year so look in sections 712 and 716. There is a list of requirements you have to meet under 716.5.4 to not have a fire damper in a duct penetration. Section 712 also has some bits about pipe.

I also suggest you ask him exactly where he got that info from to double check.

 

[CountOlaf]

There is an exception in the International Mechanical Code (IMC) (607.5.3) where ducts penetrate fire partitions (other than group H occupancies) if the duct does not exceed 100 sq. in. (0.06 sq m.), which the 160 mm would qualify for. There are a few other requirements to meet this exception including a steel sleeve, min. duct thickness, must be above a ceiling, no terminations with a wall register, no openings communicating the corridor with adjacent spaces, etc.

Check out the applicable state code/IMC in your area to be sure.

 

[willard3]

A fire damper is placed in firewalls for a very good reason, to prevent the spread of fire. Put in the damper. You think the fire comes to a 100 sq in opening and doesn't go through?

We frequently forget that code requirements are minimum requirements. Try to do better than the minimum.

 

[DrRTU]

What is the rating of the wall (partition)? If the partition carries a 1hr rating, then you may be able to utilize the details found in NFPA 90A to demonstrate the need not to install a fire damper. This is unlimited penetration cross sectional area.

 

[mauricestoker]

It may also depend on the classification of occupancy, and whether the duct is for exhuast. If a wet lab and exhaust duct,or approved for treatment as such, you would have no fire dampers.

 

[berkshire]

If you are putting in a requirement for a fire damper in a fire wall, also put in a requirement for inspecting it.
Several times in my life I have retro-fitted ducts to find that over the years the fire damper has dissolved into a pile of rust that would not stop a fire on a bet.
However due to there being no code to inspect it. the fire damper has lain useless for years.
B.E.

 

[mauricestoker]

There is an inspection requirement; every four years, I believe.

 

[Zesti]

There used to be a rule like that over here in The Netherlands but now all ducts going through a fire rated wall require a fire damper.

(In some cases, if the duct was larger than 160mm, the dirty trick of splitting the main duct into smaller ones before passing the wall could be used...)

 

[hollandhvac]

Ok some additional information

The wall is 2 hours fire rated.

The duct is for fresh air supply to the rooms of an office building.

And thanks Zesti,but, designer is from France and the project is in north africa and we work as per American standards.