CUSTOMER SUPPORT
고객지원
자료실
FAN LAWS
-
- 작성일
- 2022-03-23
-
- 조회수
- 2298
FAN LAWS
The following fan laws apply for the range of air performance where induction motor dirven blowers operate, that is, under 2.5m of water static pressure or vacuum (where it may be assumed that air is incompressible). The fan laws may also be used if the pressure of both fan conditions is over 2.5m of water but the pressure change is less than 30%.
Effect of a speed change
For example, a blower is operating at 3500rpm and delivering 800 CMM. If the speed is reduced to 3000rpm, What is the new volume?
V2= V1 X (RPM2/RPM1) = 800 X (3000/3500) = 800 X 0.857 = 686 CMM
PRESSURE CHANGES AS THE SQUARE OF THE SPEED RATIO
For example, a blower is operating at a speed of 3500 rpm and delivering air at 200mbar. If the speed is reduced to 3000rpm, What is the new Pressure?
P2 = P1 X (RPM2/RPM1)2 = 200 X (3000/3500)2 = 200 X 0.735 = 147mbar
AIR DENSITY VARIES IN INVERSE PROPORTION TO ABSOLUTE TEMPERATURE
For example, a blower is to handle 150℃ air at 200mbar. What pressure (Standard air) blower is required?
P2 = P1 X (AT1/AT2) = 200 X (273+150)/(273+20) = 200X 0.692 = 288mbar
HORSEPOWER CHANGES AS THE CUBE OF THE SPEED RATIO
For example, a blower is operating at a speed of 3500rpm and requiring 5 horsepower. If the speed is reduced to 3000rpm, What is the new horsepower?
HP2 = HP1 X (RPM2/RPM1)3 = 5 X (3000/3500)3 = 5 X 0.63 = 3.15 HP
The following fan laws apply for the range of air performance where induction motor dirven blowers operate, that is, under 2.5m of water static pressure or vacuum (where it may be assumed that air is incompressible). The fan laws may also be used if the pressure of both fan conditions is over 2.5m of water but the pressure change is less than 30%.
Effect of a speed change
- CMM is proportional to speed (The volume change in direct ratio to the speed)
CMM2=CMM1 X (RPM2/RPM1) - SP is proportional to speed2 (The Pressure change as the square of the speed ratio)
SP2=SP1 X (RPM2/RPM1)2 - HP is proportional to Speed3 (The HP change as the cube of the speed ratio)
SP2=SP1 X (RPM2/RPM1)3
- CMM is constant
CMM2=CMM1 - SP is proportional to density
SP2=SP1 X (d2/d1) - HP is proportional to density
HP2=HP1 X (d2/d1)
For example, a blower is operating at 3500rpm and delivering 800 CMM. If the speed is reduced to 3000rpm, What is the new volume?
V2= V1 X (RPM2/RPM1) = 800 X (3000/3500) = 800 X 0.857 = 686 CMM
PRESSURE CHANGES AS THE SQUARE OF THE SPEED RATIO
For example, a blower is operating at a speed of 3500 rpm and delivering air at 200mbar. If the speed is reduced to 3000rpm, What is the new Pressure?
P2 = P1 X (RPM2/RPM1)2 = 200 X (3000/3500)2 = 200 X 0.735 = 147mbar
AIR DENSITY VARIES IN INVERSE PROPORTION TO ABSOLUTE TEMPERATURE
For example, a blower is to handle 150℃ air at 200mbar. What pressure (Standard air) blower is required?
P2 = P1 X (AT1/AT2) = 200 X (273+150)/(273+20) = 200X 0.692 = 288mbar
HORSEPOWER CHANGES AS THE CUBE OF THE SPEED RATIO
For example, a blower is operating at a speed of 3500rpm and requiring 5 horsepower. If the speed is reduced to 3000rpm, What is the new horsepower?
HP2 = HP1 X (RPM2/RPM1)3 = 5 X (3000/3500)3 = 5 X 0.63 = 3.15 HP