ALL >> Environment >> View Article
Fans Performance CurvesBy Expert Author: Oleg Tchetchel
The fan curve presents fan performance. It is one of the most useful tools available during the fan selection process. While multi-rating tables are convenient (see page 12), performance curves offer additional information such as - how much reserve pressure head exists between the design pressure and the peak static pressure, the maximum power the fan might draw, and the efficiency of operation.
Fan curves are based on laboratory test data and are sometimes referred to as "test curves". A typical test curve will often define the performance parameters for a specific design and size of fan, operating at a given speed, moving a gas of a given density. Inspection of this graph will show that it is actually composed of four separate curves:
• Static Pressure vs. Volume Curve: This plot is the one often referred to as the "fan curve" or "characteristic curve" because it defines all the possible pressure-volume combinations the fan is capable of producing given stated conditions (i.e. rpm and gas density). Note that this curve has two regions - one marked by dashed lines and the other by a solid line. Fans must be selected so that the design point is located on a solid portion of the curve, preferably in an area of high operating efficiency. Operation on the dashed portion of the curve should be avoided as it is a zone of potentially unstable performance. For this reason it is wise to allow some reserve between the peak static pressure and the design pressure to compensate for a higher resistance to flow than anticipated by the design calculation.
• Static Efficiency vs. Volume Curve: In most instances it is desirable to have a fan perform as close to its peak efficiency as possible. The static efficiency vs. volume curve illustrates the efficiency of fan performance at a glance.
• Power vs. Volume Curve: This plot illustrates the power draw of the fan for any point on the characteristic curve.
• System Curve: The system curve defines the volume flow rate versus pressure characteristics of the system in which a fan will be installed.
For most applications, the volume flow rate to pressure relationship is governed by the following equation, often called the "duct law":
Once the system designer has determined the system pressure loss (P) for one flow rate (CFM), it is very easy to calculate the corresponding pressure loss for any other flow rate using this "law". The system curve is not included on the performance curve when it is issued from the fan manufacturer and its determination is left to the system designer.
At this juncture it is prudent to reiterate that a fan running at a particular speed can have an infinite number of operating points all along its characteristic curve. The fan will interact with the system to produce an operating point at the intersection of the system curve and the fan curve. Note that it is the system in which the fan is installed that will determine the operating point on the fan curve. Thus it is vitally important that the system designer accurately determine the system losses in order to ensure that the actual air flow rate is as close as possible to the design air flow rate.
For additional information please refer to http://canadianblower.com/fans/index.html
Industrial Process Ventilating Designer
Environment Articles1. Do Solar Panels Work In The Winter?
Author: Melissa McDonald
2. Shocking Video Of Pakistani Guy Played On Skype
Author: Sohaib Sauleh
3. Maintenance With Machinery Top 3 Tips To Remember
4. Engage In Nature Based Teen And Youth Programs And Get Benefited
Author: Animal Tracking
5. Learning About Mold Mitigation And Removal In Broward
Author: Lionale Donald
6. Hiring Water Damage Specialist In Miami
Author: Lionale Donald
7. Build Green Pathways With Nghm For A New Game Changer
Author: National Green Highways Mission- NGHM
8. Ideal Destination To Get Professional Water Quality Monitoring Services
Author: Gondwana Environmental Solutions
9. Positivity For Everything Is A Good Habit To Adopt
Author: News Cafe
10. Sbs Water Systems Ltd, A Source For Efficient Water Storage Solution
Author: John Edwilk
11. Un Alquiler De Coches En Alicante Carabinero Se Despechuga La Cubana
Author: Neal Hindmarsh
12. Aquel Alquiler De Coche En Alicante Festón Flocula Esta Similara
Author: Franklyn Raggatt
13. Aquel Alquiler Coche Barato Alicante Cual Alza Menos El Poeta
Author: Delbert Dial
14. Deal With Water Damage Restoration In Miami
Author: Lionale Donald
15. Dealing With Climate Change Issues
Author: Sanjukta Singh