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narkom
05-01-2014, 03:08 PM
Hi!
There is a CENTRIFUGAL UPBLAST BELT DRIVE FAN
11057

The fan technical data are below
11058

As one can see, the fan brake horse power (power consumption) is 0.50. The question is which the motor shaft power should be? Taking into consideration the belt drive losses.

Segei
05-01-2014, 04:39 PM
This is electrical motor number not the fan.

B G Scott
07-01-2014, 08:08 AM
With constant impeller size
break horse power absorbed varies as (speed of rotation)3

With constant speed of rotation
break horse power absorbed varies as (impeller size)5

For a full explanation of the fan laws Google "Woods Guide to fan engineering"

narkom
07-01-2014, 08:37 AM
OK!
That is the performance data
11059
At 2000 CFM and 075" static pressure the BHP is 0,43HP.
Will 0,50HP motor shaft power be enough?

B G Scott
07-01-2014, 09:13 AM
OK!
That is the performance data
11059
At 2000 CFM and 075" static pressure the BHP is 0,43HP.
Will 0,50HP motor shaft power be enough?

To fully evaluate the BHP absorbed by the fan you will need additional information, which should be available from the manufacturer.
You would need either "fan total efficiency" or "fan static efficiency" then you can use the formula

BHP absorbed = CFM x fan static pressure (iwg) divided by 6350 x fan static efficiency
or
BHP absorbed = CFM x fan total pressure(iwg) divided by 6350 x fan total efficiency

Frikkie
19-01-2014, 10:06 AM
Hi!
.......Taking into consideration the belt drive losses.
Are you sure that fan has belts?

None of the RPM and CFM figures in the table are the same as the numbers on the fan.
If the fan is 1/2 HP then if it's a standard sized motor it will be .37kW which is nominally a half horse power. I can't believe they don't give a maximum motor run current on the info plate.

Some ranges of fans use non-standard motor sizes that are precisely matched to the shaft power requirement of the blade set, these are specially manufactured and should be replaced with the exact same motor from the fan supplier.