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In equal friction method for air duct sizing.what are the exact friction value?

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Question ajoutée par AZIZ FAYEZ
Date de publication: 2015/06/15
magdy abd al nour
par magdy abd al nour , HVAC Site manger , First United Co.

it isn't constant ....every building is different ....you the cfm form AHU and the air velocity to get the friction  

Hasan Riaz
par Hasan Riaz , Mechanical Engineer , Saudi Bin Ladin Group (Hamad International Airport)

Typical range of design equal friction loss rates used for Low Velocity systems are from0.08 to0.15" w./100 ft of duct.

For High Velocity systems, friction loss rate may be as high as0.6" w./100 ft.

Now the exact friction value is in this range is the compromise between optimized friction loss and economical duct sizing. So a nominal value can be used which varies case to case of projects.

Muhammad Yusuf Ali
par Muhammad Yusuf Ali , Sr.Mechanical Engineer , Saudi Electricity Company

You can use any value below0.1" WG for low velocity duct sizing calculation. for example0.075" wg/100 FT.

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