System effect factors for various duct elbows

From ASHRAE (1988), with permission

Notes:

Square elbow with inlet transition -- No turning vanes

A11-4a.gif (13045 bytes) R/H No
duct
2D
duct
5D
duct
0.50 2.50 1.60 0.80
0.75 2.00 1.20 0.66
1.00 1.20 0.66 0.33
2.00 0.80 0.47 0.26

Square elbow with inlet transition -- Three long turning vanes

A11-4b.gif (19339 bytes)

R/H No
duct
2D
duct
5D
duct
0.50 0.80 0.47 0.26
1.00 0.53 0.33 0.18
2.00 0.26 0.22 0.14

Square elbow with inlet transition -- Short turning vanes

A11-4c.gif (15405 bytes)

R/H No
duct
2D
duct
5D
duct
0.50 0.80 0.47 0.26
1.00 0.53 0.33 0.18
2.00 0.26 0.22 0.14