Fire Dampers installation detail 3

[mechanical3010]

The question is about the minimum acceptable gauge thickness for sleeves used to house the fire damper which is then secured to the fire rated wall using angles bolted to the sleeve on all four sides.
For UL Listed Type B Fire Dampers, the minimum gauge thickness of the sleeve must be the same as the gauge of the duct to which it is attached. The gauge thickness of the duct is governed of course by SMACNA standards. The duct gauge for small sized ducts (14 inches) the gauge thickness for low pressure ducts (1/2 inch W.G. Static pressure) is gauge 26. Is it permissible to use the same gauge thickness of 26 for fire damper sleeves or is there a minimum gauge thickness for sleeve of type B fire dampers also, as gauge 18 is the absolute minimum for type C fire dampers? Likewise if the duct gauge is 22 can the sleeve be gauge 22 also or there is a minimum gauge.

 

[iken]

This may be like flogging a dead duck, but I thought I would do some more looking into this for my own benefit, and have come accorss the following.

HVCA have published a guide DW/145, which seams to hit a couple of items, and looks like this is not a push at more or any of their (or others) guides/standards. Yes this seems a bit over the top for fire dampers etc, until you sit back and say to yourself - these are a life safety item, and hence need to operate correctly.

The main item is that in general, all fire dampers MUST be installed as per manufactures recommendations (and details), as these will be what the fire dampers were tested to (and hence how they obtain their fire rating). If you are putting a fire damper in a sleeve, has this method been approved/tested etc?

Does the manufacture offer these dampers in a sleeve, if so what grade of sheetmetal.
Have these dampers been tested in a sleeve (will they operate in a sleeve)?

Just more food for thought.

 

[berkshire]

I am going to stick my toe in this water and see if I get flogged back out of it.
""Figure 6.2 of this UL555 allows the duct connection with flat drive slip. This is enigmatic, because the connection of duct to sleeve does not remain breakway if jointed by drive slips on two verticle sides. The breakaway connection is to enable the duct to detach from the sleeve without pulling down the damper assembly with it. Once the duct is fixed to the sleeve with drive slips, it does not appear to be break away anymore?""

Isn't UL555 an installation schedule for testing fire dampers as opposed to a normal installation schedule. And does it not specify drives fitted vertically with no S joints so the duct can slide straight down in the event of a failure.
Ok flog away.
B.E.