Vektor-MD Performance - Introduction, Selection Information

Vektor-MD Performance - Introduction, Selection Information
High Plume Dilution - Vektor
Laboratory Exhaust System
The Greenheck Vektor™ High Plume Dilution Blower (patented)
employs a unique discharge nozzle design that entrains additional
ambient air, diluting the exhaust effluent from the laboratory, which
reduces exhaust contaminant concentration. More important,
the addition of the ambient air increases the Vektor’s discharge
windband mass flow and velocity, resulting in greater nozzle
discharge momentum, displacing the diluted exhaust high above
the roof.
How Vektor Technology Works...
Laboratory exhaust is drawn into the Vektor fan (A). The exhaust is
discharged into the Vektor induction nozzle and ambient dilution air
is induced into the Vektor nozzle (B). The laboratory exhaust plus
induced dilution air is discharged at high velocity to atmosphere (C).
Greenheck Fan Corporation
certifies that the model
Vektor™-MD shown herein
is licensed to bear the
AMCA Seal. The AMCA
Certified Ratings Seal applies
to Induced Flow Fan Air
and Sound Performance
(AMCA Standard 260). The
ratings shown are based on tests and
procedures performed in accordance
with AMCA Publication 211 and 311 and
comply with the requirements of the AMCA
Certified Ratings Program.
C
B
Vektor™-MD Inline Mixed Flow
High Plume Dilution Blower
Model Vektor™-MD is listed
for electrical (UL/cUL 705). File no. E40001
A
Why use the Greenheck Vektor Lab Exhaust System?
The main objective of a laboratory exhaust system is to remove hazardous or noxious fumes from a laboratory,
dilute the fumes as much as possible and expel them from the lab building so that the fumes do not
contaminate the roof area or become re-entrained into the building make-up air system.
The Greenheck Vektor™ High Plume Dilution Blower is a self-contained laboratory exhaust system, which offers
the following benefits:
• Significant plume rise without unsightly exhaust
stacks that detract from buildings aesthetics
• Significant dilution of laboratory exhaust, reducing
levels of contaminant concentration
• Inline mixed flow configuration
• Reliable belt or direct drive systems
• Efficient and quiet blower technology
• Unique “vacuum shaft seal” ensuring that
hazardous or noxious fumes do not escape through
the shaft opening (patent pending)
• AMCA class C or B spark-resistant construction
• L10 200,000 hour minimum life fan shaft bearings
• Premium high-efficiency motor as standard
• Application to constant or variable volume
exhaust systems
• Efficient discharge nozzle design
• LabCoat™ a two-part corrosion-resistant baked
polyester resin powder coating with zinc-rich
epoxy primer
• Safe and easy maintenance
• Flow applications from 1,500 - 80,000 cfm and up to
8 in. ESP per fan
• Multiple fan assemblies on a factory provided
common plenum
• Meets ANSI Z9.5, UL 705, and ASHRAE lab
design guidelines
No one tests and certifies performance like Greenheck!
2
Vektor-MD Mixed Flow
Design Features
• Uses roof mounted inline blower to remove and dilute laboratory exhaust
• Ideal for applications:
– Where roof space is limited (minimal footprint)
– Demands high levels of exhaust at moderate to high static pressures
• Utilizes mixed flow impeller technology (U.S. Patent 7048499)
Benefits:
• Efficient operation for reduced energy consumption
• Lower overall sound levels - 5-20 dB less than inline centrifugal or axial
exhaust fans
Vektor Housing
Bypass Air
Damper
Mixed Flow
Wheel
Isolation
Damper
Construction:
• Heavy-gauge, welded steel
• Available with AMCA spark C or B construction
• LabCoat™ electrostatically powder coated with corrosion-resistant
Hi-Pro Polyester and zinc-rich epoxy primer – Dark Gray 041 (standard)
• Range of optional colors available
• Lifting lugs and guards manufactured with coated stainless or
galvaneal steel
Bypass Air
Lab Exhaust (Effluent)
Bypass Air Plenums:
• Single or multiple Vektor-MD inline exhaust blowers
• Modular in design to easily adapt to different configurations
• Can be added to a system on retrofits
• Available in single- or double-wall construction
• Designed to handle windloads up to 125 mph without guy wires
• Bypass air and isolation dampers
– Low-leakage airfoil blades
– LabCoat™ electrostatically powder coated with corrosion-resistant
Hi-Pro Polyester and zinc-rich epoxy primer Dark Gray 041 (standard)
– Sized specifically for each application
– Factory-mounted electric or pneumatic actuators available
Features
Belt Drive
Belt Drive
• AMCA arrangement 9
• Provides safe, easy inspection and maintenance of fan drive components
• Housing is bifurcated with motor, belts, and bearings located outside of
contaminated airstream
• Motor or drive replacement does not require removal of fan from the system
or exposure to contaminated interior
• Drive sized for 200% of the motor horsepower
• Minimum of two drive belts
• Ability to adjust fan RPM to compensate for system static pressure
variations (balancing) and future system performance requirements
Direct Drive
• AMCA arrangement 2
• Utilizes a unique design offering safe and easy motor
replacement
• Utilizes a single rigid self-aligning coupling, connecting
the motor shaft to the impeller shaft
• Motor bearings do not support the weight of fan
impellers: Longer motor life
Direct Drive
3
Laboratory Exhaust Systems
Model VektorTM-MD
Greenheck Fan Corporation
certifies that the model
Vektor™-MD shown herein
is licensed to bear the
AMCA Seal. The AMCA
Certified Ratings Seal applies
to Induced Flow Fan Air
and Sound Performance
(AMCA Standard 260). The
ratings shown are based on tests and
procedures performed in accordance
with AMCA Publication 211 and 311 and
comply with the requirements of the AMCA
Certified Ratings Program.
AMCA Induced Flow Licensed
The Air Movement and Control Association (AMCA) International, Inc. has introduced AMCA Standard 260,
“Laboratory Methods of Testing Induced Flow Fans for Rating.” Induced flow fans, also known as high plume
dilution blowers, are used to dilute hazardous laboratory exhaust and disperse the exhaust high into the
atmosphere, away from possible re-entrainment zones. Prior to AMCA Standard 260, high plume dilution blowers
fell outside the scope of AMCA performance certification. Now, AMCA Standard 260 can provide consulting and
facility engineers independent performance verification for critical laboratory exhaust applications that they insist
on for other fans and blowers used in general HVAC applications.
Greenheck's Vektor™-MD is licensed to bear the AMCA Induced Flow Fan Air and Sound Certified Ratings
Seal. Each fan size has been tested in our AMCA accredited air and sound laboratory and their performance as
cataloged is assured. The AMCA Induced Flow Fan seal encompasses the following AMCA test standards:
•ANSI/AMCA Standard 210, “Laboratory Methods of Testing Fans for Certified Aerodynamic
Performance Rating”
•AMCA Standard 260, “Laboratory Methods of Testing Induced Flow Fans for Rating”
•AMCA Standard 300, “Reverberant Room Method for Sound Testing of Fans”
Visit http://www.AMCA.org for more information regarding AMCA Standards and Publications.
4
Laboratory Exhaust System Terminology
Bypass Air - Ambient air that is drawn
through the bypass air plenum and mixed
with the lab exhaust to increase dilution and
plume rise. Bypass air is primarily utilized in
variable volume applications to maintain a
constant discharge volume.
Windband
Fan Housing
Dilution - The ratio of the total fan outlet
volume to the lab exhaust volume.
Motor Cover
Effective Plume Height - Sum of the
discharge plume rise, plus the added height
of the laboratory exhaust system above the
roof-deck level. (See diagram on page 6)
Entrained Air - Air that is drawn through the
windband and mixed with the lab exhaust to
increase the dilution and plume rise.
Mixed Flow
Wheel
Isolation Damper
Cover
Lab Exhaust - Air that is being exhausted
from the laboratory.
Nozzle - Located at the discharge of the fan
housing, the nozzle is used to accelerate the
exhaust air as it enters the windband.
Isolation Damper
Section
Isolation Damper
Bypass Damper
Bypass Air Plenum
Weatherhood
Roof Curb
Plume Rise - The height of the propelled lab
exhaust and dilution air above the discharge
of the windband.
Total Airflow - The sum of the lab exhaust,
bypass air, and entrained air.
Total Airflow
Windband - Device used to direct the lab
exhaust as it leaves the housing of the
exhaust fan and entrain dilution air.
Variable Nozzle Technology (VNT) Greenheck Vektor-MD exhaust fans offer
multiple nozzles and windbands to optimize
the plume rise, efficiency, and sound levels
of the fan. Greater nozzle velocities result
in increased air entrainment and higher
plume rise.
Entrained Air
Entrained Air
Bypass Air
Exhaust Air
5
AMCA 260 Air Test Procedure
The following illustrations describe the procedure for determining the total laboratory exhaust fan discharge flow.
The total discharge flow is the sum of inlet airflow and entrained airflow. The key requirement to AMCA 260 is
the variable resistance box. This box allows the measurement of total discharge flow (Ps = 0 in. wg to simulate
discharging the fan to atmosphere) at all points along its fan curve.
Without the variable resistance box, the entrained airflow can only be measured at the free air point of its fan
curve. The entrained airflow obtained can be used to calculate an effective plume height. Therefore, AMCA 260
certification is necessary to ensure the laboratory exhaust fan specified is providing the plume rise and
entrainment submitted.
ANSI/AMCA 210 Figure 15 Test
Air Test Chamber
Entrained
Air
Inlet
Airflow
Flow Direction
Flow Direction
Flow
Total Total
Airflow
Entrained
Air
Total Airflow Measurement
Variable
Supply
System
Determines inlet airflow (cfm).
AMCA 260 Figure 1 Test
Air Test Chamber
Entrained
Air
Variable Resistance Box
Inlet
Airflow
Flow Direction
Total Flow
Entrained
Air
Flow Direction
Total Flow
Total
Airflow
Ps = 0 in. wg*
Total Airflow Measurement
*To simulate atmospheric conditions
Variable
Exhaust
System
Determines outlet airflow (cfm) at the same inlet
conditions measured in the Figure 15 test.
6
AMCA 260 Air Test Procedure cont’d
The entrainment ratio can be determined by dividing the outlet airflow from the AMCA 260 Figure 1 test, by the
inlet airflow from the AMCA 210 Figure 15 test.
VEKTORMD-30LVHP100
Effective Plume Height {ft} @ 10 mph Crosswind = (Outlet Volume) + 16
1020
16
rpm - Fan Inlet Airflow
rpm - Windband Outlet Airflow
Windband Outlet Area = 15.4 ft2
6
0
3
2
1
0
0
0
87
2
M
AX
RE
SIS
TAN
CE
CUR
VE
4
Static Pressure (in. wg)
6
4
Entrainment
Ratio
=
Entrainment
Ratio
=
Outlet Airflow
Inlet Airflow
or
(
Figure 1 test
Figure 15 test
)
70
8
0
10
5
11
Static Pressure (Pa x 100)
6
13
12
Outlet
Airflow
Operating
Point
14
10
0
10
20
Volume (CFM x 1000)
20
30
3
40
30
30,000 cfm
17,500 cfm
=
171 %
40
50
60
70
Volume (m /hr x 1000)
Note: When selecting a fan size please use the fan inlet airflow curve only (
)
AMCA 300 Sound Test Procedure
Greenheck is the first company in the laboratory exhaust fan industry to receive AMCA 260 certification and is
also leading the industry when it comes to sound testing. Greenheck tests the outlet sound of the fan with the
entire fan located inside the reverberant room according to AMCA 300 Figure 3 below.
Inlet Sound
Reverberant
Room
Airfl
Reverberant
Room
Microphone
Path
Microphone
Path
AMCA 300 Figure 2: Fan Inlet Testing
Figure 1: Fan Inlet(Installation
Sound
Figure
Testing
1: A:
Fan
Inlet
Testing
Type
Free
Inlet,Sound
Free Outlet)
Fan
Reference
Sound
Source
Reverberant
Fan
Room
Microphone
Path
ow
Airfl
Fan
Reference
Sound
Source
Reference
Sound
Source
ow
Airfl
Fan
ow
Reference
Sound
Source
Outlet Sound
Reverberan
Room
Microphone
Path
AMCA 300 Figure 3: Fan Outlet Testing
Figure 2: Type
FanA:Outlet
Sound
Figure
Testing
2: Fan
(Installation
Free Inlet,
Free Outlet)
Outlet Sound Testing
Installation Type A: Free Inlet,
Installation
Free Outlet
Type A: Free Inlet, Free Outlet
Installation Type A: Free Inlet,
Installation
Free Outlet
Type A: Free Inlet, Free Outlet
(Ratings do not include the(Ratings
effects do
of duct
not include
end correction)
the effects of duct end correction) (Ratings do not include the(Ratings
effects do
of duct
not include
end correction)
the effects of duct
All Vektor-MD high plume dilution blowers have been tested in our third party accredited sound laboratory and
their performance as cataloged is assured.
7
Effective Plume Height
It is important that the exhaust plume height be great
enough to avoid re-entrainment of exhaust air and to
disperse the exhaust. The effective plume height should
be used when analyzing design issues. The effective
plume height (he ) is the physical height of the fan
system (hs ) plus the plume rise (hr ), found from the
equation below.
The effective plume height is calculated using the following equation*:
he = hr + hs
Quick Select Chart
Fan
Size
15
16
18
20
he= [3.0 x (V x d / U)] + hs
Note: Fan curves include effective plume height
equations that are specific to the fan size located
in the air data section of this catalog.
hs = fan height (dimensions section of this catalog)
hr = plume rise, ft (m)
22
24
27
30
V = windband exit velocity, ft/min (m/s)
d = windband diameter, ft (m)
33
U = wind speed, ft/min (m/s)**
* From ASHRAE Laboratory Design Guide, Equation 9-2
** P
lume rises shown on performance pages are calculated
with a 880 ft/min, [10 mph], (4.47 m/s) crosswind.
36
40
44
49
Laboratory Exhaust
cfm
3
Effective Plume Height he
m /h
ft.
m
5.2
Min
1,300
2,200
17
Max
5,500
9,300
34
10.4
Min
1,600
2,700
19
5.8
Max
7,000
11,900
39
11.9
Min
2,000
3,400
21
6.4
Max
8,500
14,400
42
12.8
Min
2,500
4,200
22
6.7
Max
10,500
17,800
47
14.3
Min
5,000
8,500
27
8.2
Max
14,000
23,800
50
15.2
Min
6,000
10,200
28
8.5
Max
17,500
29,700
52
15.9
Min
7,500
12,700
32
9.8
Max
20,000
34,000
55
16.8
Min
9,000
15,300
34
10.4
Max
25,000
42,500
62
18.9
Min
8,000
13,600
31
9.5
Max
30,000
51,000
61
18.6
Min
9,500
16,100
33
10.1
Max
35,000
59,500
65
19.8
Min
12,000
20,400
36
11.0
Max
44,000
74,800
73
22.3
Min
14,000
23,800
40
12.2
Max
54,000
91,700
75
22.9
Min
17,500
29,700
44
13.4
Max
66,000
112,100
83
25.3
Note: Plume rise ranges shown above are based on
3,000 fpm (15.25 m/s) minimum discharge velocity per
ANSI Z9.5 with a 10 mph (16.09 km/hr) crosswind per
ASHRAE Applications Handbook.
hr
hr
hs
he
he
hs
Note: When manually selecting a fan it is important to
remember that more than one fan is available to meet
the desired performance. Selection criteria such as
fan size, efficiency, speed, outlet velocity, horsepower,
sound, or construction material may also dictate
which fan is chosen.
Note:hGraphical
= h + hcomparison of Vektor-MD to low velocity, traditional stack.
e
s
r
Adjusting Plume Height
Adjusting the fan system to have additional throw or plume height is achieved by increasing the volume of air
through the discharge nozzle. Simply changing the drive pulleys will increase fan speed and volume capacity,
thus boosting flow momentum. The additional air through the fan comes from an increase in lab exhaust or an
increase of air through a bypass air damper. Utilizing a bypass air damper to increase both dilution and mass
flow of the exhaust air can optimize plume rise. Increased mass flow improves momentum and carries the diluted
exhaust higher.
The plume height can also be adjusted by changing nozzles. A higher velocity nozzle results in higher outlet
airflow, which in turn results in higher plume rise.
8
Air Density Correction Factors
Elevation (Feet Above Sea Level)
Air
Temp.
°F
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
10000
11000
12000
13000
14000
15000
-20
0.83
0.86
0.89
0.93
0.96
1.00
1.03
1.07
1.11
1.15
1.19
1.24
1.28
1.33
1.38
1.43
-10
0.85
0.88
0.91
0.95
0.98
1.02
1.06
1.09
1.14
1.18
1.22
1.27
1.31
1.36
1.41
1.46
0
0.87
0.90
0.93
0.97
1.00
1.04
1.08
1.12
1.16
1.20
1.25
1.29
1.34
1.39
1.44
1.50
10
0.89
0.92
0.95
0.99
1.03
1.06
1.10
1.14
1.19
1.23
1.28
1.32
1.37
1.42
1.47
1.53
32
0.93
0.96
1.00
1.04
1.07
1.11
1.15
1.20
1.24
1.29
1.33
1.38
1.44
1.49
1.54
1.60
50
0.96
1.00
1.03
1.07
1.11
1.15
1.20
1.24
1.29
1.33
1.38
1.44
1.49
1.54
1.60
1.66
70
1.00
1.04
1.08
1.12
1.16
1.20
1.24
1.29
1.34
1.39
1.44
1.49
1.55
1.60
1.66
1.72
100
1.06
1.10
1.14
1.18
1.22
1.27
1.31
1.36
1.41
1.47
1.52
1.58
1.63
1.69
1.76
1.82
125
1.10
1.14
1.19
1.23
1.28
1.32
1.37
1.42
1.48
1.53
1.59
1.65
1.71
1.77
1.84
1.90
150
1.15
1.19
1.24
1.28
1.33
1.38
1.43
1.48
1.54
1.60
1.66
1.72
1.78
1.85
1.91
1.98
175
1.20
1.24
1.29
1.34
1.39
1.44
1.49
1.55
1.60
1.66
1.72
1.79
1.85
1.92
1.99
2.07
200
1.25
1.29
1.34
1.39
1.44
1.49
1.55
1.61
1.67
1.73
1.79
1.86
1.93
2.00
2.07
2.15
Density Correction Factor Equation
DCF = ((T + 460)/530) x 1.037(E / 1000)
DCF = Density Correction Factor
T = Temperature (degrees F)
E = Elevation above sea level (feet)
Air Density (lb/ft3) = 0.075 / DCF
Effects of Air Density
When selecting a fan to operate at a non-standard air density using standard air density tables and curves,
corrections must be made to static pressure and brake horsepower.
At higher than standard elevations and temperatures, air density will be lower than standard. Therefore, static
pressure must be determined at standard density that will equate to the specified static pressure at the operating
density. Since standard air density is greater than operating air density in this instance, one would expect the
corrected static pressure to be greater than the operating static pressure.
The following example shows how to select a Vektor-MD Size 30, 85% Wheel Width, Low Velocity (LV)
Nozzle for 17,000 cfm, 4 in. wg, 1000 ft. elevation, and 125°F temperature.
1.Since the volume exhausted by the system is not affected by density, cfm remains 17,000.
2.Select the correction factor from the chart for 1000 ft. elevation and 125°F. Correction factor is 1.14.
3.Multiply specified static pressure (4 in. wg) by the correction factor (1.14) to determine standard air
density equivalent static pressure. {4 in. wg x 1.14 = 4.56 in. wg}
4.Using the performance curves, enter 17,000 cfm and 4.56 in. wg of static pressure.
5.At the intersection of 17,000 cfm and 4.56 in. wg static pressure, the fan rpm is approximately 1450 rpm
and Bhp is 20.
6.Since the horsepower selected refers to standard air density, this must be corrected to reflect actual
Bhp at the lighter operating air. Remember, horsepower is less at a lower air density. Divide the Bhp
required (20) by the correction factor (1.14) selected previously to determine the Bhp at the new
operating conditions.
20/1.14 = 17.5 Bhp. This would require a minimum motor size of 20 hp.
9
Vektor-MD Selection: AMCA 260
Inlet Airflow 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-MD requires the 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 height.
3)Determine fan rpm
1)Determine the laboratory exhaust requirements
•
Determine the lab exhaust volume per fan.
•
Determine the external static pressure at the
system inlet.
•
Locate the fan operating point (the intersection
of the required airflow and static pressure) on
the inlet airflow in Figure 1.
In this example, the operating point is
17,500 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 1360 rpm curve.
Direct drive fan selections must use the 50 or
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
15, but slightly less than 20 hp. A minimum of a
20 hp motor is recommended for this selection.
B
Bypass Air Plenums - Estimated Pressure Drop
• Variable volume lab exhaust systems require a
bypass air plenum and damper.
• Greenheck’s Computer Aided Product
Selection (CAPS) software, automatically adds
external system static pressure to account for
the bypass air plenum and isolation damper.
C
2)Select the appropriate Vektor-MD
A
•
Select Vektor-MD 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.
4)LV, MV and HV Nozzles
All Vektor-MD curves indicate the
minimum cfm necessary to meet this
minimum velocity.
Each fan size is available with Low
Velocity (LV), Medium Velocity (MV) or High
Velocity (HV) nozzles.
•
Multiple nozzles 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.
Figure 1: Vektor-MD Size 30 Low Velocity 100% Wheel Width
6
Nozzle Velocity (fpm) = Inlet Volume / 5.45
%WOV = (CFM x 100) / (RPM x 17.6)
IS
TA
NC
EC
UR
VE
75
ES
X
MA
R
4
5
8
10
12
16
Volume (CFM x 1000)
15
20
3
25
30
Volume (m /hr x 1000)
10
60
Static Pressure (in. wg)
13
70
0
50
0
0
HP
0
1
5
12
2
HP
10
Static Pressure (Pa x 100)
3
HP
0
0
7.
5
87
2
10
95
4
A
4
11
6
HP
8
B
HP
10
RPM
HP
3
Density 0.075 lb/ft
15
5
12
50 cycle RPM
C
60 cycle RPM
Nozzle Velocity: 3000 fpm
20
14
20
35
24
40
Vektor-MD Selection: AMCA 260
Outlet Airflow Curves
igure 2 below illustrates the new AMCA 260 fan curves. Each fan has two performance curves associated with
F
each rpm: the red curve is the flow through the fan and the blue curve directly to the right is the windband exit
volume. These curves have been connected with shading.
1)Determining windband exit volume
•
E Draw a horizontal line to the right from to
E
Find the operating point .
the blue windband
exit curve F .
•
F , so the windband exit volume is 30,000 cfm.
The windband exit volume is determined by 2)Determining windband velocity, dilution ratio and effective plume height
ach Vektor-MD size and nozzle combination has a unique set of equations to determine the nozzle velocity,
E
dilution ratio, and effective plume height. Since the operating point is 17,500 cfm at 4 in. wg, calculations are as
follows for a Vektor-MD Size 30-LV.
Windband Exit Volume = 30,000 cfm
Nozzle Velocity = 17,500 cfm/5.45 ft2 = 3211 ft/min
Dilution Ratio = Windband Exit Volume/Fan Inlet Airflow = 30,000 cfm/17,500 cfm = 171%
(
(
Effective Plume Height =
Outlet Volume
1020
30,000
1020
)
)
+ 16
+ 16 = 45 ft
ote: Effective Plume Height includes the fan height of 16 ft. as indicated in the dimensions section of
N
this catalog.
Determining Inlet and Outlet Sound
Along with the fan rpm, it is necessary to know the fan percent wide open volume (%WOV). The %WOV can be
calculated using the equation posted adjacent to each fan curve.
%WOV (Vektor-MD-30-LV) = (cfm x 100) / (rpm x 17.6). For this example, the %WOV is 73%.
The sound power and sound pressure can be determined through linear interpolation between sound data
provided at 1170 rpm and 1360 rpm.
VEKTORMD-30LVHP100
Figure 2: Vektor-MD
Size 30 Low Velocity 100% Wheel Width
Effective Plume Height {ft} @ 10 mph Crosswind = (Outlet Volume) + 16
1020
16
rpm - Fan Inlet Airflow
rpm - Windband Outlet Airflow
Windband Outlet Area = 15.4 ft2
6
14
0
3
2
1
0
0
0
0
87
2
4
M
AX
RE
SIS
TAN
CE
CUR
VE
4
F
70
6
E
11
8
5
Static Pressure (in. wg)
10
60
Static Pressure (Pa x 100)
13
12
10
10
20
Volume (CFM x 1000)
20
30
3
40
30
40
50
60
70
Volume (m /hr x 1000)
Note: When selecting a fan size please use the fan inlet airflow curve only (
)
11
Vektor-MD Selection: Reading Fan Curves
There are several variables in selecting an appropriate Vektor-MD system including % wheel width and nozzle
size. These factors will affect the required brake horsepower, fan RPM, and entrained air. As a general rule, the
low velocity nozzle will require less brake horsepower than the high velocity nozzle, but entrained air and plume
rise will be slightly less. Higher pressures can be achieved by using reduced % wheel widths. Belt drive units
are available in 100%, 85%, and 70% wheel width. Direct drive units are available from 100% - 50% wheel width
in increments of 5% (i.e. 95%, 90%).
Step 1: Identify necessary laboratory effluent (CFM), plume rise (ft), and % dilution. Enter the Vektor-MD quick
select chart located on page 8 and identify unit sizes that can accommodate application specifications. Also
determine if belt or direct drive is desired. For direct drive units, only the blue RPM curves are available for
60 cycle power and gold curves for 50 cycle power. Belt drive units are capable of operation at any RPM within
the max fan class RPM (the last RPM curve).
Step 2: Using the guidelines above, locate fan size that generally suits specifications. Calculate necessary
system pressure including isolation damper, bypass air plenum, and system drop. (See below) Enter the fan
curve with the desired performance specifications: airflow (CFM), pressure (in. wg), and nozzle outlet velocity
(fpm). This yields horsepower (HP) and RPM at the fan operation point. If the given point has a close proximity
to a horsepower curve, the next larger motor horsepower should be selected.
Pressure Drop
Variable volume lab exhaust systems and systems that require additional bypass air, require a bypass air damper
and plenum. When calculating necessary pressure, 0.2 in. wg must be added to the external system static
pressure to account for the bypass air plenum. Add 0.15 in. wg if the system includes an isolation damper.
Vektor-MD Size 30
6
75
IS
TA
NC
EC
UR
VE
60
A
Step 2
ES
Static Pressure (in. wg)
13
• Considering the desired performance criteria, a
Vektor-MD size 30 Belt drive with 100% wheel
width and low velocity nozzle (LV) is selected to
optimize unit size and required horsepower.
70
0
HP
50
0
0
5
0
1
HP
12
2
HP
10
Static Pressure (Pa x 100)
3
• From the quick select chart, applicable unit sizes
range from Vektor-MD size 24 to Vektor-MD
size 44.
0
0
7.
5
87
2
10
95
4
4
11
6
HP
8
HP
10
• Lab system A requires 17,500 cfm exhaust, 56 ft.
plume rise, with an external static pressure of
4 in. wg.
RPM
HP
3
Density 0.075 lb/ft
15
5
50 cycle RPM
60 cycle RPM
Nozzle Velocity: 3000 fpm
20
14
12
Example A:
Nozzle Velocity (fpm) = Inlet Volume / 5.45
%WOV = (CFM x 100) / (RPM x 17.6)
X
MA
R
4
5
8
10
12
16
Volume (CFM x 1000)
15
20
3
25
30
20
35
24
40
Volume (m /hr x 1000)
NOTE: All plots represent fan operation at standard air (70°C at sea level).
ANSI Z9.5 specification requires a 3,000 fpm minimum nozzle outlet velocity.
• Locating this point on the curve (A), a 20 HP motor
is needed to operate at 1360 RPM and provides
3,211 fpm nozzle velocity.
• Using the %WOV equation provided with the
Vektor-MD size 30, 100% wheel width, LV nozzle
air data chart, the %WOV can be calculated:
%WOV = (17,500 x 100) / (1360 x 17.6) = 73 % WOV
Vektor-MD Model Guide
Vektor-MD- 15-9-85-LV-HVW
Vektor MD - Mixed Flow,
High Plume Dilution
Fan Size — Sizes 15 - 49
Fan Arrangement
9 = Belt Drive
2 = Direct Drive
Windband Type
HVW =High Velocity Windband
HPW = High Plume Windband
Nozzle Type
LV = Low Velocity
MV = Medium Velocity
HV = High Velocity
Wheel Width
50 - 100% in increments of 5%
12
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