Vektor-CD Performance Catalog - Greenheck

Vektor-CD Selection: Fan Curves
Every laboratory or fume exhaust application has a unique set of criteria that must be evaluated in order to
determine the most effective exhaust system. The selection of a Vektor-CD requires the total lab exhaust volume
(effluent) per fan along with a determination of the external static pressure. Other considerations when making
fan selections include: sound requirements, electrical limitations, size constraints, and the effective plume rise.
1) Determine the laboratory exhaust requirements
• Determine the total lab exhaust volume
(effluent) per fan.
• Determine the external static pressure entering
the fan system.
Bypass Air Plenums - Estimated Pressure Drop
• Variable volume lab exhaust systems and
systems adding dilution air require a bypass air
plenum and damper.
• Greenheck’s computer aided product selection
software (CAPS), automatically adds external
system static pressure to account for the
bypass air plenum and isolation damper.
2) Select the appropriate Vektor-CD
A Select Vektor-CD fans with a minimum
nozzle velocity of 3,000 feet per minute
(ANSI Z9.5 and ASHRAE lab design
guidelines), which is represented by the
green vertical line in Figure 1.
• All Vektor-CD curves indicate the
minimum cfm necessary to meet this
minimum velocity.
3) Determine fan rpm
• Locate the fan operating point (the intersection
of the required airflow and static pressure) on
the performance curve in Figure 1.
In this example, the operating point is
B
17,000 cfm at 4 in. wg.
The belt drive fan rpm can be estimated by
comparing the operating point to any of the
solid fan rpm curves and in this example, the
operating point falls on the red 1734 rpm curve.
Direct drive fan selections must use the 50 or
C
60 cycle rpm curves (yellow or blue curves).
• Determine the brake horsepower by comparing
the operating point to the dashed brake
horsepower curves.
In this example, the brake horsepower is above
20, but slightly less than 30 hp. A minimum of a
30 hp motor is recommended for this selection.
4) LV, MV and HV Nozzles
D Each fan size is available with Low Velocity
(LV), Medium Velocity (MV), or High
Velocity (HV) nozzles.
• Multiple nozzles (VNT) allow for the optimization
of brake horsepower, plume rise and
acoustic performance.
Note: For most applications, the LV or MV nozzles are
recommended in order to limit the operating brake
horsepower. HV nozzles are available for applications
that require the highest plume rise.
16
VEKTORCD-30HV
Figure 1: Vektor-CD Size 30 High Velocity
A
60% WOV
50 Cycle RPM
60 Cycle RPM
C
35
14
70% WOV
Static Pressure (Pa x 100)
30
25
20
15
10
5
0
Static Pressure (in. wg)
RPM
HP
WOV
Density 0.075
12
10
8
6
4
2
720
870
950
MAX RESISTANCE CURVE
2 hp
1170
5 hp
1450
7½ hp
10 hp
1734
1900
15 hp
2050
25 hp
20 hp
0
0 4 8 12 16 20 24 28 32
Volume (cfm x 1000)
80% WOV
90% WOV
0 10 20 30 40 50
Volume (m 3 /hr x 1000)
2182
30 hp
40 hp
50 hp
60 hp
B
100% Wheel Width
Windband
Outlet Area
Class II Fan
Max rpm
Class III Fan
Max rpm
Performance
Data
= 8.3 ft 2 Nozzle Velocity
{ft/min}
= 1734
= 2182
Effective Plume @ 10 mph Crosswind
Height {ft}
(3 * Windband Outlet Volume * 0.392)
880
+ 11.50
% WOV
3000 fpm: Inlet
Airflow Rate
D
LV MV HV
Fan cfm Fan cfm Fan cfm
4.35 ft 2 3.48 ft 2 2.61 ft 2
cfm x 100
rpm x 14.3
cfm x 100
rpm x 13.6
cfm x 100
rpm x 12.2
13050 cfm 10440 cfm 7830 cfm
10