17
Selection Process
Selection Process
Drive Package
The following are the design requirements for UATN60C unit:
Model:
UATN60C
Supply Air Quantity
=
2000
CFM
External Static Pressure
=
180
Pa
Step 1: From the fan curve (at 2000 CFM),
Standard operating system;
Internal Static Pressure
=
115
Pa
Step 2: Therefore at 2000 CFM and 180 Pa external static pressure,
Total Static Pressure
=
180 + 115
Pa
=
295
Pa
Step 3: From the blower curve, the design requirement calls for RPM about 1200 RPM.
From the table:
Motor pulley
=
100
mm
Blower pulley
=
140
mm
Motor RPM
=
1430
In order to obtain 1200 RPM, we calculate the new blower pulley as:
(while maintaining the motor pulley)
Db
=
100 x (1430/1200)
= 119.17 mm
Let us take close approximation of 120 mm diameter pulley size
Recheck, with Db =
120 mm
Blower pulley
=
1430 x (100/120)
=
1192 RPM
We thus need to change the blower pulley from 140 mm to 120 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)
= 675.4
We thus can use a belt with a length of
680 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
=
0.75
kW
ii) Blower pulley diameter
=
120
mm
iii) V-belt size
=
680
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.
Summary of Contents for UATN60CGXY1
Page 2: ......
Page 4: ...Table of Contents ii...
Page 48: ...44 Wiring Diagrams Wiring Diagrams Model UATN60 90C...
Page 49: ...45 Wiring Diagrams Model UATN120 150 180C...
Page 50: ...46 Wiring Diagrams Model UATN210 240 300C...
Page 55: ......
