Question about HVAC Dampers

Dear Mohan.

Fire damper mostely used when you are crossing expension joint,entring from one zone to an other zone,crossing the wall,just after the AHU rooms.entring in any lab or espesial area,at present mostly using every out let or returen.Siddiqui

Whenever a duct penatrates a fire wall, the duct must contain a fire damper at that point. Your local fire code will spell out the exact reqirement.

There are several things to consider. Normally a fusable link damper is used but you have to consider the air pressure in the duct. Sometimes it might not close due to high velocity and such. A motorized damper will shut, if installed properly. Another good thing about a motorized damper is that end switches can be used and indicators to tell if it is closed or not. I have hunted all over the place trying to find why the air flow was low only to find a fusable damper closed that people forgot was in the system. Higher cost and maintenance are a consideration as well.

N5EBA,

Many thanks for your reply, so can we put sum up a given below?

1) To decide whether to put a fusible fire dampers or a motorozied FD depends on the pressure of flow in the respective ducts

2) If you think the presssure inside the duct is not enough to

close the flow (can we get this data for pressure from the MSDS of Fusible FD???) then motorized dampers has to be considered.

Please confirm

rgds

biju

I think you have a good feel for the problem now. The damper manufacturer can give you good guidance on when to use or not use a fusible link damper.