Stack on commercial roof question...

[Wheelbaron]

OK here is a dumb question. I feel silly asking this but I got to know.

What is the purpose of the exhaust stacks on some commercial buildings that are rectangular and half way up it makes a expansion and the reduces back to the original size? Is this for a damper of some sort? Shape kind of like this:


l l
l l
/ \
\ /
l l
l l

[Wheelbaron]

No body? do I need a picture?

[Lash]

no-loss stacks

Normally they are venting for some type of exhaust fan of off an industrial oven, kitchen hood, or boiler equipment.

Do they look similar to these?

http://www.remediationequipment.com/10,000%20CFM%20catalytic%20Products%20unit.JPG

http://www.langdonsheetmetal.com/mediac/400_0/media/DIR_14401/16$20Gauge$20Aluminized$20No$20Loss$20Oven$20Stack .jpg

http://www.remediationequipment.com/Thermaloxidizer16000.JPG

[keepyoucool2003]

I've seen them also, one of those things I never wondered. I'll ask around and see if someone knows what I'm talking about.

[keepyoucool2003]

I think he's takling about something diffrent... picture a stack say 14x14 vertical off a roof about 3 feet high, then that 14"x14" transitions into 24x24 for 1' then back to 14"x14" for another 2' of so. I'm trying to remember where I've seen this before, I don't have an answer since I forgot to ask.


no-loss stacks

Normally they are venting for some type of exhaust fan of off an industrial oven, kitchen hood, or boiler equipment.

Do they look similar to these?

http://www.remediationequipment.com/10,000%20CFM%20catalytic%20Products%20unit.JPG

http://www.langdonsheetmetal.com/mediac/400_0/media/DIR_14401/16$20Gauge$20Aluminized$20No$20Loss$20Oven$20Stack .jpg

http://www.remediationequipment.com/Thermaloxidizer16000.JPG

[Lash]

I bumping an old thread because it just poped into my head today....lol.

Those stacks look like this inside: <<<<>>>>
They have a bunch of splitters in there. It's typically used in paintbooth set-ups. The splitters will and increased duct size slow down velocity and knock down any larger paint particles to keep them from blowing out of the stack and all over the building including everything around it.