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24
Selection Process
Selection Process
Drive Package
The following are the design requirements for 2FGN250HY1 unit:
Model:
2FGN250HY1
Supply Air Quantity
=
9000
CFM
External Static Pressure
=
350
Pa
Step 1: From the fan curve (at 9000 CFM),
Standard operating system;
Internal Static Pressure
=
250
Pa
Step 2: Therefore at 9000 CFM and 350 Pa external static pressure,
Total Static Pressure
=
250 + 350
Pa
=
600
Pa
Step 3:
From the blower curve, the design requirement calls for RPM about 880 RPM.
From the table:
Motor pulley
=
90
mm
Blower pulley
=
180
mm
Motor RPM
=
1440
In order to obtain 880 RPM, we calculate the new blower pulley as:
(while maintaining the motor pulley)
Db
=
90 x (1440/880)
= 147.27 mm
Let us take close approximation of 147 mm diameter pulley size
Recheck, with Db =
147 mm
Blower pulley
=
1440 x (90/147)
=
882 RPM
We thus need to change the blower pulley from 180 mm to 147 mm in order to obtain the higher operating
static pressure.
Step 4:
When the pulley is changed, the V-belt length must be rechecked. We have for horizontal air throw
configuration:
V-belt length, L
=
2C + 1.57 (Db + Dm)
=
(2x165) + 1.57(120+100) (2x640) + 1.57(147+90)
= 1652.09
We thus can use a belt with a length of
1650 mm
where,
C
=
distance between the centres of the two pulleys
Db
=
diameter of blower pulley
Dm
=
diameter of motor pulley
Step 5:
From the blower curve, we can also notice that the motor power input has maintained within the current
operating range of the standard unit’s motor.
Summary:
i) Fan motor kW
=
5.5
kW
ii) Blower pulley diameter
=
147
mm
iii) V-belt size
=
1650
mm
Note: Factory supplied rooftop is only with standard drive package.
All other changes are only given as example and need to be field supply.
Содержание H-Series
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Страница 72: ...68 Wiring Diagrams Wiring Diagrams Cooling Only FDN80HV1 RN80HY1 FDN100HV1 RCN100HY1...
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