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15 Cards in this Set
- Front
- Back
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What is the relation between RPM and CFM? |
(RPM(2)/RPM(1)) = ((CFM(2)/CFM(1)) ———— If RPM = 2 Then CFM = 2 |
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What is the relation between RPM and Static Pressure? |
(RPM(2)/RPM(1))^2 = (SP(2)/SP(1)) |
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What is the relation between RPM and hp? |
(RPM(2)/RPM(1))^3 = (hp(2)/hp(1)) |
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Equation for fan efficiency? |
(Air hp) / (Break hp) Output / Input |
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What is the equation that discribes the relationship between driver and driven pulley? |
RPM(driver) x Diameter (driver) = RPM(driven) x Diameter (driven) |
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What are the 2 types of classifications of fans?
What type of pressure do each classification does each fan produce? |
(1)Centrifugal produces static pressure (1.1)Air moves perpendicular to shaft. (2)Axial fans produce velocity pressure (2.1)Air moves parallel it shaft
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Forward curved fans? Overloading or non-overloading? High or low static applications? Other properties? |
Overloading Low static Low speed / quiet operation
Note: if 2 forward curved fans are in parallel then the max percent of free delivery. |
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Backward Inclined fans? Overloading or non-overloading? High or low static applications? Other properties? |
Backward incline 82% eff Backward curved 86% eff Airfoil 90% eff Non-Overloading Higher static pressure than forward curve Double RPM than forward |
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Propeller curved fans? High or low static applications? |
VERY LOW STATIC PRESSURE |
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Airfoil fans? High or low static applications? Other properties? |
Most suitable for VAV applications. |
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FANS SUMMARY PAGE |
Back (Definition) |
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What is the relation between CFM and static pressure |
IF RPM=CFM RPM^2=Static Pressure Therefore CFM^2 = Static Pressure
(CFM(2)/CFM(1))^2 = ((SP(2)/SP(1)) |
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What are the 2 ways centrifugal fans produce pressure? |
Two was in which centrifugal fans produce pressure: • Centrifugal force that is generated when the air is rotated between the blades • Kinetic energy created by the velocity of the air when it leaves the fan impeller blade |
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How is axial different from centrifugal fans in terms of airflow and shaft direction? |
Air flows parallel to the shaft for axial. Air flows perpendicular to the shaft for an centrifugal fan. |
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What is better about forward inclined vs backward? |
Forward is slower so cheaper to produce, less noise |
