BALANCING KITCHEN EXHAUST DUCTS

[rajisha2002]

HELLO ALL,
I have encountered an installation wherein kitchen exhaust steel ductwork connected to kitchen hoods at various floors in a hotel and then to a common extract fan needs to be balanced.The fresh air supply to the hoods connected by galvanised ductwork have balancing dampers but NFPA 96 disallows dampers in grease exhaust kitchen ducts,please explain how do we balance the system

Thanks

 

[SAK9]

Kitchen exhaut serving serving various floors so that fire can spread from one kitchen to another!!!and fire dampers are also not allowed on kitchen exhaust ducts!!!

I say pack your bags and run from this site...

 

[willard3]

If this is real kitchen exhaust covered by the codes, balancing of fans is the least of your problems.

 

[chialiang]

Hi all,
normally what we did for kitchen exhaust was introduce 95% of make up air from outside to the kitchen exhaust. Is it consider air balancing for you? Normally we do not allow fire damper at the kitchen exhaust duct.

 

[JMAviles]

Try in thi site:

http://www.greenheck.com/pdf/kitchen/EABBOctober2003.pdf

No tengo talentos especiales, pero sí soy profundamente curioso.

Albert Einstein - y Yo!!!

I have no special talent. I am only passionately curious.

Albert Einstein - And Me!!!

 

[texanman]

Here is one approach: you can design your connecting duct diameter in such a way to create a pressure drop that can act like a flow damper. This is called proportioanl balancing and is sometimes used in hydronic flow distribution systems. It will take some design and engineering calcs.
Basically, the farthest duct to hood will have the largest diameter, the the closest to the fan will have smaller diameter.
hope this helps.

 

[berkshire]

rajisha2002 (Mechanical)
In the past on installations like this, I have found curtain type fire dampers where the ducts pass through fire walls.

I have also found that after several years the blades of these fire dampers, are nothing but piles of rust in the bottom of the duct from the steam coming up the duct.
B.E.