Table of Contents
Advertisement
FAN LAW EXAMPLES
Fan Law 1
The formula for Fan Law 1 (built into this calculator) is:
Fan laws use the temporary storage registers a, b, a-new, and b-new.
Fan Law 1 calculates using the entry of the three known variables
and Ç R to calculate the unknown fourth value.
Example 1:
A 1,250 CFM fan is running at 750 RPM, but it needs to supply
1,400 CFM. What is the RPM required?
KEYSTROKE
1. Enter current CFM into "a" old:
o o
1 2 5 0 Ç 4
2. Enter new CFM into "a-new":
1 4 0 0 Ç 7
3. Enter current RPM into "b" old:
7 5 0 Ç 5
4. Calculate new RPM or "b-new":
Ç R
Example 2:
You set up a fan with a VFD for 14,000 CFM running at 855 RPM.
You change the RPM to 1050. What is the new CFM?
KEYSTROKE
1. Enter current CFM into "a" old:
o o
1 4 0 0 0 Ç 4
2. Enter current RPM into "b" old:
8 5 5 Ç 5
3. Enter new RPM into "b-new":
1 0 5 0 Ç 8
4. Calculate new CFM or "a-new":
Ç R
where,
CFM = Feet
3
RPM = Revolutions per Minute
CFM
per Minute
A
STORED
A
n
STORED
B
STORED
RPM
FAN LAW1 840.
n
A
STORED
B
STORED
B
n
STORED
FAN LAW1 17192.98
n
U
'
G
SER
S
UIDE
DISPLAY
0.
1250.
1400.
750.
DISPLAY
0.
14000.
855.
1050.
— 75
Advertisement
Table of Contents
