Fan Curves
Click here to load reader
Transcript of Fan Curves
![Page 1: Fan Curves](https://reader038.fdocuments.us/reader038/viewer/2022100523/547ab8b2b479599a098b4a89/html5/thumbnails/1.jpg)
How to Read a Fan Curve
![Page 2: Fan Curves](https://reader038.fdocuments.us/reader038/viewer/2022100523/547ab8b2b479599a098b4a89/html5/thumbnails/2.jpg)
Fan Curves
Three main components• CFM
• Static Pressure
• Brake Horsepower
![Page 3: Fan Curves](https://reader038.fdocuments.us/reader038/viewer/2022100523/547ab8b2b479599a098b4a89/html5/thumbnails/3.jpg)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0 2 4 6 8 10 12 14 16 18
CFM x 100
Pre
ssur
e
Fan Curve (Pressure to CFM relationship)
![Page 4: Fan Curves](https://reader038.fdocuments.us/reader038/viewer/2022100523/547ab8b2b479599a098b4a89/html5/thumbnails/4.jpg)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0 2 4 6 8 10 12 14 16 18
CFM x 100
0
0.05
0.1
0.15
0.2
0.25
0.3
Bra
ke H
orse
Pow
er
Brake Horsepower Curve (CFM to BHP relationship)
![Page 5: Fan Curves](https://reader038.fdocuments.us/reader038/viewer/2022100523/547ab8b2b479599a098b4a89/html5/thumbnails/5.jpg)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0 2 4 6 8 10 12 14 16 18
CFM x 100
Pre
ssur
e
0
0.05
0.1
0.15
0.2
0.25
0.3
Bra
ke H
orse
Pow
er
Typical Fan Performance Curve
![Page 6: Fan Curves](https://reader038.fdocuments.us/reader038/viewer/2022100523/547ab8b2b479599a098b4a89/html5/thumbnails/6.jpg)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0 2 4 6 8 10 12 14 16 18 20
CFM x 100
Pre
ssur
eConstant Horsepower Curve
![Page 7: Fan Curves](https://reader038.fdocuments.us/reader038/viewer/2022100523/547ab8b2b479599a098b4a89/html5/thumbnails/7.jpg)
Typical System Resistance Curve
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0 2 4 6 8 10 12 14 16 18
CFM x 100
Pre
ssur
e
System Resistance Curve
Sum of all system components:• Ductwork• Elbows• Transitions• Filters• Coils• Dampers• Louvers• Building pressure
Ps = k * CFM2
Pressure Increases with the Square of CFM!
![Page 8: Fan Curves](https://reader038.fdocuments.us/reader038/viewer/2022100523/547ab8b2b479599a098b4a89/html5/thumbnails/8.jpg)
Varying System Resistance Curve
0
0.2
0.4
0.6
0.8
1
1.2
1.4
0 2 4 6 8 10 12 14 16 18
CFM x 100
Sta
tic P
ress
ure
Going from curve A to curve B is an example of a system that a damper closes or filters get dirty.
Curve B
Curve A
Increasing Resistance to flow
![Page 9: Fan Curves](https://reader038.fdocuments.us/reader038/viewer/2022100523/547ab8b2b479599a098b4a89/html5/thumbnails/9.jpg)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0 2 4 6 8 10 12 14 16 18
CFM x 100
Pre
ssur
e
0
0.05
0.1
0.15
0.2
0.25
0.3
Bra
ke H
orse
Pow
er
Operating PointFan Performance Curve
Brake Horsepower Curve
System Resistance Curve
Operating Point
![Page 10: Fan Curves](https://reader038.fdocuments.us/reader038/viewer/2022100523/547ab8b2b479599a098b4a89/html5/thumbnails/10.jpg)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0 2 4 6 8 10 12 14 16 18
CFM x 100
Pre
ssur
e
0
0.05
0.1
0.15
0.2
0.25
0.3
Bra
ke H
orse
Pow
er
Fan Performance Curve
Brake Horsepower Curve
System Resistance Curve
Operating Point
Reading BHp Curve
![Page 11: Fan Curves](https://reader038.fdocuments.us/reader038/viewer/2022100523/547ab8b2b479599a098b4a89/html5/thumbnails/11.jpg)
0
0.5
1
1.5
2
2.5
3
3.5
0 5 10 15 20 25 30 35 40 45
CFM x 100
Pre
ssur
e
700 RPM
350 RPM
Operating Pointat 700 RPM
Operating Pointat 350 RPM
Varying Operating Points
![Page 12: Fan Curves](https://reader038.fdocuments.us/reader038/viewer/2022100523/547ab8b2b479599a098b4a89/html5/thumbnails/12.jpg)
Large change in Ps
Small change in CFM
Small change in Ps
Large change in CFM
CFM
Ps
Selecting Point of Operation
![Page 13: Fan Curves](https://reader038.fdocuments.us/reader038/viewer/2022100523/547ab8b2b479599a098b4a89/html5/thumbnails/13.jpg)
Ps
Operating Point
Optimum Range
Unstable
CFM
Selecting Point of Operation