Trane Fan User Manual
FAN-DS-2
FAN-DS-2
August 2000
Model Q™ Fans
Sizes 16 through 60
Super Q II Fans
Sizes 16 through 44
Model Q Fans
Sizes 16 through 60
Super Q II Fans
Sizes 16 through 44
Q Fan
The Model Q™ fan is a quiet, airfoil, inline fan specifically designed for air
conditioning applications. This highly
refined axial flow fan is available in 13
sizes from 1,000 through 80,000 cfm.
Small and compact, the Q fan has
proven to be the ideal air moving
device for standalone applications and
also for custom air handling units. It
can be used for supply, return and
exhaust systems.
Available in arrangement 1 (for floor
mounting of larger units with heavier
motors) and arrangement 9 (horizontal
or vertical mounting), it can be selected
in class 1, 2 and 3. Arrangement 9
permits factory mounting of the motor
on top, bottom, or either side of the fan
— see below.
Features and Benefits
Benefits
The Q (Quiet) Fan
•
The Trane Model Q fan generates less
low frequency noise (more difficult to
attenuate) than any other type of fan in
the HVAC industry. Sound level
comparisons show common vaneaxial
fans produce up to 23 db higher sound
levels than the Model Q — significant
in industrial applications. Being quieter
than centrifugal fans allows for
installations closer to building
occupants.
Saves Mechanical Room Space
•
The compact quiet Q fan saves floor
space, which reduces system first cost.
Easy To Install
•
Rigging and installation is so much
quicker and easier that total installed
cost savings are typically five percent
or more.
Low Maintenance
•
Belt-driven with fixed blades, Model Q
fan has very few moving parts. This
design results in exceptionally low
maintenance requirements. No fan
teardowns need be scheduled. In fact,
Q fans installed 25 years ago are still
operating just as quietly as when they
were installed.
Flexible Installation
•
The Model Q arrangement 9 can be set
in any position, for horizontal
discharge, angled discharge and
vertical discharge either upblast or
downflow. The only limitations placed
on this arrangement are those dictated
by good fan installation practice.
Motor slide rails and drive guard are
•
standard, at no extra cost.
AMCA Licensed Ratings
The Trane Company certifies that the
Model Q fans shown herein are
licensed to bear the AMCA Seal. The
ratings shown are based on tests and
procedures performed in accordance
with AMCA Publication 211 and
comply with the requirements of the
AMCA Certified Ratings Program.
Discharge End View
Arrangement 9 Arrangement 1
©American Standard Inc. 2000
2
Contents
Q Fan Accessories
• Inlet flange — for simplified, rigid
connection of ductwork to inlet end of
fan
Inlet screen — safety accessory
•
mounted to fan inlet. Heavy, plated
steel wire
Note: inlet screen and inlet flange are
mutually exclusive.
Inlet vanes — mechanically modulate
•
fan capacity
Inlet bellmouth — used with unducted
•
or plenum applications. Improves air
flow and reduces noise.
Inlet silencer (long or short) — flex
•
connected to Q fan
Outlet flange — for simplified, rigid
•
connection of ductwork to outlet end of
fan
Outlet screen — safety accessory
•
mounted to fan outlet. Heavy, plated
steel wire
Note: outlet screen and outlet flange
are mutually exclusive.
Outlet duct diffuser (equalizer) —
•
makes fan outlet diameter equal to inlet
diameter
Outlet flow stabilization screen — small
•
mesh outlet screen. Helps offset effect
of poor outlet airflow conditions
Outlet silencer (short or long) — flex
•
connected to Q fan
Vertical mounting legs — used with
•
arrangement 9 for vertical discharge
floor and ceiling mounted
Isolators — to eliminate vibrations for
•
floor, ceiling and vertical installations
Special coatings — to protect against
•
alkyds, acids and corrosive
environments
Access door — available on sizes 49, 54
•
and 60 for easier service
Drain — recommended to drain off the
•
condensate where moisture-laden air is
exhausted
Copper grease lines — plastic lines are
•
standard
Double acoustic enhancement —
•
insulation and perforated sheet metal
to attenuate radiated sound
Fan insulation — self-adhesive foam,
•
applied on the outside of the fan shell
to protect against moisture
Variable frequency inverter balancing
•
and reinforcement (frequency inverter
by others). This option requires
constant pitch drives.
Features and Benefits 2
Model Number Description 12
Application Considerations 13
Selection Procedure 21
Performance Data 22
Dimensional Data and Weights 48
Mechanical Specifications 54
Model Q Fan — Arrangement 9
3
This chart shows a typical NC level
comparison between common
vaneaxials, tubular centrifugals, airfoil
centrifugals and the Trane Model Q
compact fan. The shaded area
represents range of vaneaxials tested.
Trane Model Q fans require up to
85 percent less cubic space than airfoil
centrifugal fans and 40 percent less
than common vaneaxials of equivalent
installed sound level. Floor space
savings can be as much as 65 percent
when compared to the common
vaneaxial and airfoil centrifugal and
40 percent when compared to tubular
centrifugals.
™
Features and Benefits
Vaneaxial Fan
Airfoil Centrifugal Fan
Tubular Centrifugal Fan
Trane Model Q Compact Fan
4
Features
and Benefits
Super Q II Plus
More than twenty years after the
introduction of the Model Q
retains its reputation as one of the
quietest HVAC fans in the world. This
tradition of excellence continues with
the introduction of a new Q fan
acoustical enclosure and duct silencer
so effective and so compact that we
named it the Super Q II.
Super Q II Fan
Available with Model Q fans from 1,000
to 43,000 cfm, the Super Q II enclosure
inhibits radiated fan and motor noise
from entering the surrounding space. It
internally isolates the fan on high
deflection spring isolators so ductwork
can be connected directly to the
enclosure. It is uniquely designed to be
floor or ceiling mounted with ease.
™
, it still
Although the Model Q needs very little
maintenance, future maintenance
requirements were considered by
Super Q II designers. Every unit has the
bearing grease lines extended through
the casing and every unit has two full
size access panels that provide
complete access to all internal
components.
Variable Air Volume Compatible
The Super Q fan is modulated for VAV
with variable frequency drives (by
others), not with inlet vanes. Variable
speed inverter fan modulation offers
exceptional energy saving and
exceptionally quiet part load operation.
VAV variable speed Q fans are
structurally reinforced to handle the
uneven harmonic loadings associated
with variable speed fan operation. In
addition, the factory gives variable
speed Q fans a precise, 10-point
balance to further help assure troublefree operation. Only constant pitch
drives should be used with variable
frequency inverters.
Super Q II Accessories
Inlet screen — safety accessory
•
mounted to fan inlet. Heavy, plated
steel wire
Inlet bellmouth — used with unducted
•
or plenum applications. Improves air
flow and reduces noise.
Inlet silencer (long or short) — rigid
•
connection to Super Q fan
Outlet flow stabilization screen — small
•
mesh outlet screen. Helps offset effect
of poor outlet airflow conditions
Outlet silencer (short or long) — flex
•
connected to Q fan
Variable frequency inverter balancing
•
and reinforcement (frequency inverter
by others). This option requires
constant pitch drives.
Outlet screen — safety accessory
•
mounted to fan outlet. Heavy, plated
steel wire.
Super Q II
5
Features
and Benefits
Trane Plus Duct Silencer
The Plus option is a high performance
duct silencer. Designed specifically for
the Super Q II and Model Q
several unique features that reduce
airborne noise and turbulence to
exceptionally low levels. Briefly, the
Plus option develops maximum static
regain while simultaneously limiting
objectionable mid and high frequency
noise. The Plus option should be used
whenever quiet comfort is desired
and the duct system is acoustically
unable to provide it.
Trane’s Plus Silencer provides
significant noise attenuation, up to
32 db at 1,000 Hz, without a significant
increase in fan horsepower
requirements.
™
, it has
By carrying the concept of noise source
attenuation to its economic maximum,
Trane has created a fan system that can
move significant amounts of air
without creating objectionable low
frequency rumble. It provides proven
acoustical performance with less
design risk. In project after project, the
Trane Model Q fan has been the key to
creating NC 15 to NC 35 quiet
comfort jobs.
Beyond quiet, the Super Q II Plus
system is small and compact. In fact, it
is small and quiet enough that it can be
successfully installed in ceiling
plenums. Locating a Super Q II Plus in
the plenum helps reduce and even
eliminate the floor space needed for
the mechanical room.
The modular, component design
approach of the Super Q II air handling
system makes it exceptionally well
suited for renovation, retrofit and
replacement projects. The Super Q II air
handling system components (fan,
silencers, filter/coil module, etc.) fit
through most doors and elevators and
can be easily field-assembled into any
system configuration (blow-thru, drawthru, etc.).
Plus Silencer
6
Features
and Benefits
Low Sound Level, High Efficiency
Provided by Unique Aerodynamic
Features
[9] Airfoil Vanes (stationary)
[7] Hub Streamlining Insulation
[12] End Cone
[8] Exact Blade to Vane Spacing
[11] Precise Divergent Angle Diffuser
Discharge Cone
[10] Stabilizing Pitch
[4] Airfoil Blade Wheel.
[5] Aerodynamic Pitch
[6] Minimum Tip Clearance
[2] Aerodynamic Inlet Bell
Precision cast fan wheel and diffuser
for highly efficient aerodynamic
performance. [8]
Note: Call-out numbers shown above are referenced on page 8.
Precise divergent angle for maximum
static regain. [11]
[3] Aerodynamic Inlet Cone
[1] Thin Strut Patented
Bearing Support
Aerodynamic inlet provides smooth
airflow. [3]
7
Features
and Benefits
The low sound and high performance
of the Trane Model Q
by reducing noise-creating, energyconsuming turbulence within the fan.
Airflow research and development
techniques employed were similar to
those used in perfecting today’s high
performance axial flow jet engine
compressors. The resulting smooth air
path has made the Model Q the first
vaneaxial fan to provide quiet, efficient
operation, suitable for air conditioning
duty.
Aerodynamic Air Path
A component by component analysis
of the Model Q points to 12
aerodynamic features which are keys
to a smooth air path. Starting at the
inlet, the struts [1] of the patented
bearing support are precisely
positioned in relation to the fan blades.
Air passing over the struts strikes the
blades in a pattern that prevents blade
whine.
™
fan are achieved
The aerodynamically shaped inlet bell
[2] and inlet cone [3] provide uniform
axial flow parallel to the fan shaft. Air is
delivered equally to the leading edge of
the fan blades — no crowding toward
the fan tips.
Air separation is reduced by the
precision cast aluminum airfoil cross
section [4] of the fan blades. Blade pitch
[5], using a variable angle of attack in
the radial dimensions, is precisely
controlled to prevent energy loss.
Exceptionally close clearance
[6] between the blade tips and housing
reduces the eddy currents of fan tip
recirculation. The reinforcing ring
rigidizes the housing to maintain the tip
clearance. The interior of the fan wheel
is insulated to prevent hub
strengthening protrusions from
[7] windmilling in the airstream.
A precisely controlled space [8]
between the fan blades and diffuser
vanes is necessary to allow airflow
stabilization ahead of the vanes. The
vanes themselves are precision cast
aluminum and have an airfoil cross
section [9] and a precise radial pitch
[10]. This provides smooth, spiral-free
discharge.
The diffuser section design [11] is
critical. A precisely determined
diffusion angle produces the greatest
possible static regain within the
confines of the fan. An end cone
[12) covers the fan drive assembly,
thereby reducing the turbulence
generated by air passing over exposed
drives.
Precise Manufacturing Assures
Performance — Advanced
manufacturing techniques assure the
same performance characteristics for
each production Model Q fan.
Fin Struts — The fin struts of the
•
patented bearing support are precisely
positioned in relation to the fan blade.
Air passing over the struts strikes the
plate in a pattern that prevents the
irritating whine, from blade frequency,
which is characteristic of industrial
vaneaxials.
Inlet Bell and Cone — The
•
aerodynamically shaped inlet bell and
inlet cone provide uniform axial flow
into the fan parallel with the fan shaft.
Air is delivered equally to the leading
edge of the fan blades. This prevents
crowding toward the blade tip.
Wheel — The wheel consists of 8
•
precision cast blades with a twisted
radially projected shape and airfoil
cross section. This radial projection
utilizes a variable angle of attack in the
radial dimension and prevents radial
movement as the air particles move
through the wheel.
Tip Clearance — Close clearance
•
between the blade tips and housing
reduces eddy currents due to tip
recirculation. The reinforcing ring holds
the housing in its precise shape to
maintain proper clearance.
Vane Spacing — Precise space
•
between the fan blades and the diffuser
vanes is necessary to allow flow
stabilization ahead of the vanes. The 29
diffuser vanes also have an airfoil cross
section and a twisted, radially projected
shape. This provides smooth, spiralfree air discharge.
Precision Cast Aluminum Fan and
•
Diffuser — Being cast, blade and vane
shapes are permanently and precisely
fixed. They are not subject to
misalignment or distortion as are
welded, sheet metal forms.
Diffuser Section — The diffuser
•
section design is critical. A precisely
determined flare angle at the diffuser
end produces the greatest possible
static regain within the confines of the
fan. Thus, externally mounted diffuser
accessories, common for industrial
vaneaxials, are not necessary.
Hydraulically Expanded Flow-
•
Formed Housing — In this process,
the cylindrical housing is drawn to its
final form over an expansion die. The
metal, expanded beyond its elastic
limit, permanently retains the precision
form imparted by the die.
Ductile Weld Technique — This
•
technique is required for the fan
housing seam to guarantee success of
the expansion forming process. The arc
and “puddle” are submerged in
molten flux that shields the weld
material from oxidation. This prevents
brittleness and also anneals the weld.
The result is a flexible, ductile seam
capable of being drawn and formed —
another example of the advanced
technology used in the Trane Model
Q fan.
8
Features
and Benefits
Saving Valuable
Equipment Room Space
The Trane Model Q™ and Super Q II
fans can help you maximize your
building’s usable floor space by using
them in place of centrifugal fans. The
smaller the equipment room, the more
space left for tenants, merchandise, etc.
Figure F-1 Figure F-3
Return or Exhaust Applications
Figure F-1 shows a size 44, single
width, low pressure airfoil centrifugal
fan delivering 20,000 cfm of air.
Because of its size and weight, it is floor
mounted and connected to a return air
plenum. In contrast, a 44-inch Model Q
fan is used in Figure F-2 instead of a
centrifugal fan. Its smaller size and
lighter weight permits ceiling
suspension and approximately 75 sq ft
of floor space is freed up for other use.
Draw-Thru Supply Application
(Small Capacity)
The fan system in Figure F-3 is a
27-inch, single width, medium pressure
airfoil centrifugal fan rated at 9,000 cfm.
Even though it is a relatively small fan,
it is floor mounted beside the coil bank
plenum. Figure F-4 shows a 27-inch
Model Q substituted in place of the
centrifugal. The small size and weight,
plus the installation flexibility of the
Model Q, permits mounting in a
vertical position on top of the plenum.
The space savings is about 25 sq ft.
Figure F-2 Figure F-4
9
Features
and Benefits
Draw-Thru Supply Application
(Large Capacity)
A 60-inch, single-width, medium
pressure airfoil centrifugal fan is used
in the system illustrated in Figure F-5 to
supply 45,000 cfm of air. This capacity
can be easily achieved by installing a
pair of 40-inch Model Q™ fans in
parallel as shown in Figure F-6. The
resulting floor space savings is
approximately 85 sq ft!
Figure F-5 Figure F-7
Blow-Thru Supply Application
Figure F-7 shows a typical medium
pressure, built-up, blow-thru system.
The fan, enclosed in a plenum, is a 33inch, double width, airfoil centrifugal
that delivers 30,000 cfm of air. The
bulkiness of the plenum is dictated by
the necessary clearances around the
fan. To save floor space, a 44-inch
Model Q replaces the centrifugal in
Figure F-8. The suspended mounting of
the Model Q frees about 70 sq ft for
installation of pumps and other
equipment.
Figure F-6 Figure F-8
10
Features
and Benefits
Reduce Installed Cost
By Up To 20 Percent
The Trane Model Q™ fan, with all its
precision and quality, is still a cost
effective fan. When all necessary
system components are considered, it
provides substantial installation cost
savings. In addition, its small size and
variable mounting positions allow
more freedom to the designer and
installer.
First Cost Comparisons
True first cost is the total cost of an
operable installation. With the Trane
Model Q, this consists of only the fan,
drive and isolation. By comparison, the
airfoil centrifugal typically requires
these three components, plus an
integral base. In addition, cost of
isolation for the airfoil is greater
because it is typically twice as heavy as
the Model Q.
The common vaneaxial also requires
more components in most
applications. Besides the fan, drive and
isolation, an inlet bell and diffuser are
frequently necessary to meet cataloged
performance. A sound attenuator is
also required to reduce noise to a level
equivalent to a Model Q fan without
attenuation.
Lower Installation Costs
The Trane Model Q fan has fewer
components to install and the
advantage of lighter weight. With only
half the weight of airfoil and tubular
centrifugals, it requires less manpower
for rigging and setting the fan in place.
The result is reduced labor, with
corresponding dollar savings on the
typical job.
Lighter weight also reduces inertia pad
requirements. With the Model Q, a pad
has to be considered only on large
Table F-1 — Total Installed Cost Comparison
Item Required Centrifugal Model Q Centrifugal Vaneaxial
First Cost Requirement
Fan X X X X
Belt Guard X X X
Integral Base X
Inlet Bell X
Attenuation X
Spring Isolators X X X X
Installation Cost Requirements
Rigging X X X X
Install Attenuation X
Mount Motor (Etc.) X X
Install Isolation X X X X
Average Total Installed Cost X –5 +5 +15
Comparison is based on equal size fans of similar capacities. The airfoil centrifugal fan is used as base (100%) for
comparative purposes. Figures are based on estimates by experienced installing contractors.
Standard Trane Tubular
Class III fans. Airfoil and tubular
centrifugals, because of greater weight,
often require pads for Class I and II to
minimize the effect imposed by normal
vibration.
Combined Saving Significant
A comparison of average total installed
cost is shown in Table F-1. Average cost
figures were developed based on
estimates by experienced installing
contractors. In all cases, the Trane
Model Q represents a significant
savings.
Arrangement 9 Trane Model Q fan
requires purchase of motor, motor
rails, belt guard and isolation in
addition to the basic fan.
11
Arrangement 3 airfoil centrifugal fan
requires purchase of motor, belt
guard, motor slide rail, isolation and
subbase in addition to basic fan.
Model Number Description
Valid SelectProd. able
Cat. Item Description
CYCLE QSE E-cycle 16-44 arr 9 cl 1&2
w/o mtr mtd
QSE1 E-cycle 16-44 arr 9 cl1&2
w/mtr mtd
QSQ Q-cycle 16-44 arr 9 cl 1,2&3
MTO Std cycle 16-44 arr 1&9
cl 1,2&3 & SQ2
MTO1 Std cycle 16-44 arr 1&9
w/unit coating
MTO2 Std cycle 49-60 arr 9 cl 1&2
MTO3 Std cycle 49-60 arr 9
w/unit coating
MODEL QFNA Q (Quiet) fan
TYPE SQ2 Super Q2 fan
QFAN Q fan
SIZE 16 Fan size 16” (400 mm)
19 Fan size 19” (475 mm)
21 Fan size 21” (525 mm)
24 Fan size 24” (600 mm)
27 Fan size 27” (675 mm)
30 Fan size 30” (750 mm)
33 Fan size 33” (825 mm)
36 Fan size 36” (900 mm)
40 Fan size 40” (1000 mm)
44 Fan size 44” (1100 mm)
49 Fan size 49” (1225 mm)
54 Fan size 54” (1350 mm)
60 Fan size 60” (1500 mm)
ARRG 9 Arrangement 9 fan
1 Arrangement 1 fan
CLASS 1 Class 1 fan
2 Class 2 fan
3 Class 3 fan
UORT UP Upblast discharge
DOWN Downblast discharge
H Horizontal discharge
MTRS TT Trane supplied motor &
Trane mounted
FT Field supplied motor &
Trane mounted
TF Trane supplied motor &
field mounted
FF Field supplied motor &
field •mounted
TRES WB Thrust restraints WB
(direct ship)
NONE No thrust restraints
DUCT YES Duct canvas
WBAL FACT Q fan inverter factory
balancing
FIELD Inverter ready balanced by
customer
Valid SelectProd. able
Cat. Item Description
MTHP 1 Motor hp 1 (.7 kW)
1.5 Motor hp 1.5 (1 kW)
2 Motor hp 2 (1.5 kW)
3 Motor hp 3 (2 kW)
5 Motor hp 5 (4 kW)
7.5 Motor hp 7.5 (5.5 kW)
10 Motor hp 10 (7 kW)
15 Motor hp 15 (11 kW)
20 Motor hp 20 (15 kW)
25 Motor hp 25 (18 kW)
30 Motor hp 30 (22 kW)
40 Motor hp 40 (30 kW)
50 Motor hp 50 (37 kW)
60 Motor hp 60 (44 kW)
75 Motor hp 75 (56 kW)
MTYP HEOP18ODP High eff mtr 1800 rpm
1S/1W
ODP12 ODP High eff mtr 1800/
1200 rpm 2S/2W
ODP91 ODP High eff mtr 1800/
900 rpm 2S/1W
ODP92 ODP High eff mtr 1800/
900 rpm 2S/2W
PHOP18ODP Prem Hi E+3 mtr
1800 rpm 1S/1W
HETE18 TEFC High eff mtr 1800 rpm
1S/1W
PHTE18 TEFC Prem Hi E+3 mtr
1800 rpm 1S/1W
VOLT 200 200 Volt 60 hertz 3 ph motor
208 208 Volt 60 hertz 3 ph motor
230 230 Volt 60 hertz 3 ph motor
460 460 Volt 60 hertz 3 ph motor
575 575 Volt 60 hertz 3 ph motor
MOLO R Motor location right hand
drive
L Motor location left hand
drive
T Motor location top drive
B Motor location bottom drive
GRSL N Nylon grease lines
C Copper grease lines
DTYP C1.2 Constant pitch drive with
1.2 DSFT
C1.4 Constant pitch drive with
1.4 DSFT
C1.5 Constant pitch drive with
1.5 DSFT
V1.2 Variable pitch drive with
1.2 DSFT
V1.4 Variable pitch drive with
1.4 DSFT
V1.5 Variable pitch drive with
1.5 DSFT
Valid SelectProd. able
Cat. Item Description
INSL F Fan insulation
FA Fan and accessories
insulation
ENHA DBLE Double acoustic
enhancement
COAT BPI Baked phenolic (heresite)
inside
BPIO Baked phenolic (heresite)
in/outside
EI Epoxy inside
EIO Epoxy inside/outside
EPI Epoxy phenolic
(2 components) inside
EPIO Epoxy phenolic (2
components) inside/outside
EPADI Epoxy phenolic (air dry
heresite) inside
EPADIO Epoxy phenolic (air dry
heresite) inside/outside
PEI Polyester (sanitile) inside
PEIO Polyester (sanitile) inside/
outside
IOPT IB Inlet bell
IF Inlet flange
ISC Inlet screen
IBSC Inlet bell with inlet screen
SH Inlet silencer short
L Inlet silencer long
IV Inlet vanes
NONE No inlet options
OOPT OFLG Outlet flange
OSCN Outlet screen
ODEQ Outlet duct equalizer
ODOF Outlet duct equalizer w/
outlet flange
SH Outlet silencer short
L Outlet silencer long
NONE No outlet options
ISOL SLF Free standing spring floor
isolators
C Housed spring floor isolators
ND Dbl deflection neoprene
floor isolators
RSL Spring rail floor isolators
MSL Steel base w/spring floor isol
KSL Concrete inertia base w/spring
floor isolators
HD Dbl deflection neoprene
ceiling isolators
HS Spring ceiling isolators
DNHS Spring & neoprene ceiling isol
WR Neoprene wall isolators
ADOR MS Access door motor side
OS Access door opp. motor side
9R Access door 90° right of motor
9L Access door 90° left of motor
DRAN YES Drain
MTGL IL Inlet mounting legs
OL Outlet mounting legs
12
Application Considerations
This section assists the system
designer in application and control of
Trane Q and Super Q II fans.
Satisfactory distribution of conditioned
air requires a properly chosen fan and
a well designed duct system.
Abbreviations
sp ...... static pressure (in. of water)
vp ...... velocity pressure (in. of water)
tp....... total pressure (in. of water)
ov ...... outlet velocity (ft per minute)
rpm ... fan speed (revolutions per min.)
bhp ... brake horsepower
p ........ air density (lbs/ft3)
db...... decibel (sound power or sound
pressure level)
cps .... cycles per second
cfm.... cubic feet of air per min. at any
density
scfm .. cubic feet per min. of standard air
clean, dry air with a density of
0.075 lbs/ft3 at 70 F and a barometer
reading of 29.92- inches Hg)
The System
An air system may consist of a fan,
ductwork, air control dampers, cooling
coils, heating coils, filters, diffusers,
noise attenuation, turning vanes, etc.
The fan is the component in the system
which provides energy to the airstream
to overcome the resistance to flow of
the other components.
System Component Losses
Every system has a combined
resistance to flow which is usually
different from every other system and
is dependent upon the individual
components in the system. The
determination of the “pressure loss” or
“resistance to flow,” for the individual
components can be obtained from the
component manufacturers. The
determination of pressure losses for
ductwork and branch piping design is
well documented in standard
handbooks such as the ASHRAE
Handbook of Fundamentals.
System Curve
At a fixed volume flow rate (cfm)
through a given air system, a
corresponding pressure loss, or
resistance to this flow, will exist. If the
flow rate is changed, the resulting
pressure loss, or resistance to flow, will
also change. The relationship
governing this change for most
systems is:
PRESSUREc/PRESSURE = (CFMc/CFM)
2
The characteristic curve of a typical
“fixed system” plots as a parabola in
accordance with the above
relationship. Typical plots of the
resistance to flow versus volume flow
rate are shown with normalized duct
system curves, Figure A-1.
Figure A-1 — Normalized Duct System Curves
For a fixed system, an increase or
decrease in system resistance results
from an increase or decrease in the
volume flow rate along the given
system curve only.
Refer to Duct System A, Figure A-1.
Assume a system design point at
100 percent volume and 100 percent
resistance. If the volume flow rate is
increased to 120 percent of design
volume, the system resistance will
increase to 144 percent of the design
resistance in accordance with the
system equation. A further increase in
volume results in a corresponding
increase in system pressure. A
decrease in volume flow to 50 percent
results in a 75 percent reduction in
design resistance.
13
Application
Considerations
Performance Data Determination
The fan performance section of this
catalog contains a fan performance
table and fan curve for each fan size.
The performance data contained in this
catalog was calculated from tests
conducted in accordance with AMCA
Standard 210 Laboratory Methods of
Testing Fans for Rating.
The AMCA test procedure uses an
open inlet and 10 wheel diameters of
straight discharge ductwork to assure
maximum static regain. The fan is
direct driven by a dynamometer.
The fan performance tables in this
catalog are based upon standard air:
0.075 lbs/ft
29.92-inches Hg).
Fan Performance Curves
A fan performance curve is a graphical
presentation of the performance of a
fan. Usually it covers the entire range
from free delivery (wide open cfm, no
obstruction to flow) to no delivery
(blocked tight, an airtight system with
no air flowing).
The point of intersection of the system
curve and the fan performance curve
determines the point of operation and
actual flow volume. If the system
resistance has been accurately
determined and the fan properly
selected, their performance curves will
intersect at the design flow rate. Refer
to Figure A-2. The normalized Duct
System A from Figure A-1 has been
plotted with a normalized fan
performance curve.
Temperature and Altitude Corrections
The fan performance values in the
tables and curves of this catalog are
based on standard air (.075 lbs/ft
the airflow requirement for a particular
job is stated in terms of nonstandard
air, a density correction needs to be
made before selecting the fan. It is
important to also note that most air
friction charts for ducts, filters, coils,
etc. are also based on standard air and
corrections must be made to determine
proper losses at other conditions.
Figure A-3 illustrates the ratio of air
densities to standard air at various
temperatures and elevations. A Q fan is
designed for operation between -20 F
and 150 F only.
3
(70 F, barometric pressure
3
). If
Figure A-2 — Point of Operation — Interaction of the System Curve
and the Fan Performance Curve
Figure A-3 — Air Density Corrections
14
Application
Considerations
The following is the procedure to use
when selecting a fan for elevations and
temperatures other than standard:
1
Determine the air density from
Figure A-3.
2
Divide static pressure at the nonstandard condition by the air density
ratio.
3
Use the actual cfm and corrected static
pressure to determine rpm and bhp
from the fan performance tables.
4
The rpm is correct as selected.
5
The bhp must be multiplied by the air
density ratio determined in step one to
get the actual operating bhp.
Option and Installation Kt Corrections
System effect losses due to less than
ideal inlet or outlet configuration can be
expressed in terms of velocity pressure
by the following expression:
Inlet SP Loss =
( Inlet Velocity
Kti
4005
2
)
Where Kti =
Inlet Option Kt + Inlet Installation Kt
Outlet SP Loss =
Outlet Velocity
Kto
(
4005
2
)
Where Kto = Outlet Option Kt + Outlet
Installation Kt
Kt is the loss factor for the inlet or
discharge condition being considered.
It is necessary to add all of the static
pressure loss determined from the
above equation to the component
static pressure to determine the point
of duty static pressure for selection of
the fan.
Fan Option Kt Corrections
The fan static pressure should be
adjusted for fan options. Option
pressure drops are documented as Kt
losses and are handled the same way
as installation Kt effects (losses). Use
Table A-1, Q Fan/Super Q II Fan Kt
corrections, to determine the Kt values.
Add these values to any installation Kt
values. Use the result to select the fan.
Table A-1 — Q Fan/Super Q II Fan Installation Kt Corrections
Unducted (Plenum) Inlet*
Draw-Thru Type Design 0.0
Ducted Inlet
Turn > 3 Dia Upstream -1.0
Turn 2 Dia Upstream +.8
Turn 1 Dia Upstream +1.3
Turn < 1 Dia Upstream
Unducted Outlet
Blow-Thru Type Design +.8
Ducted Outlet
Turn > 2 Dia Downstream 0.0
Turn 1 Dia Downstream +1.3
Turn < 1 Dia Downstream
Not Recommended
Not Recommended
Figure A-4 — Ducted Turns Near Q Fan
Table A-2 — Q Fan/Super Q II Fan Option Kt Corrections
Options Use Q-Fan Fan Drop (Kt)
Inlet Flange Connects to bolted inlet duct X 0
Inlet Bellmouth* Reduces Unducted Inlet Kt X X -.1
Inlet Plus Silencer Reduces inlet noise X X +.1
Inlet Screen Protects Unducted Inlets X X +.1
Outlet Screen Protects Unducted Outlets X +.5
Outlet Flange Connects to bolted outlet duct X 0
Outlet Equalizer (Diffuser) Improves SE X 0
Outlet Plus Silencer Reduces Outlet Noise X X +.1
Outlet Flow Stabilization Screen Reduces Outlet swirl X X +.8
Outlet Backdraft Damper Isolates fan from duct Special Special +.5
Frequency Drive Modulation Modulates Q Fan quietly Special Special 0
Belt Guard Protects drives/belts X 0
Motor Rails Allows motor to be mounted X Included 0
Standard Isolators Isolates fan X Included 0
Seismic Isolators Isolates fan X Special 0
*Note: Bellmouth effect included in unducted installation Kt correction. Fan sizes 49 through 60 fan curves are cataloged
with inlet bells. For unducted inlets without bells on size 49 through 60 fans add .1 to the inlet Kt given above.
Inlet vane losses are covered in the Selection Procedure with air density corrections (page 20).
Super Q II Pressure
15
Application
Considerations
Q and Super Q II Fan Modulation —
AC Inverter Capacity Control
Q fans and Super Q II fans can be
modulated with AC frequency drives.
The Trane Company recommends
Magnetek low noise inverter drives and
Century high efficiency motors for
optimum modulation performance.
Operating the Q or Super Q II fan on AC
frequency drives requires the Q fan to
be strengthened and balanced in the
factory. This option “beefs up” the
mechanical bracing of the Q fan inlet
bearing assembly and calls for a
precision factory balance. Precision
balancing covers 10 operating points
on the system curve from 10 percent
load to full load.
Minimum cfm with AC inverters —
Above 1.5” static pressure, the
minimum cfm is the surge (do not
select) line. Below 1.5” static pressure,
it is 1000 cfm.
Q Fan Modulation — Inlet Vanes
Inlet vanes are a widely used form of
fan modulation. As inlet vanes close,
they impart a spin on the incoming air
in the direction of the fan wheel
rotation. This reduces airflow, static
pressure and brake horsepower.
However, inlet vanes do increase
sound levels. If a job is acoustically
sensitive, AC inverters are
recommended for modulation. As
shown in Figure A-5, a separate cfm
static pressure curve (cfm-sp) is
generated per each inlet vane position.
Likewise, the figure shows brake
horsepower curves that apply for
various inlet vane positions.
Inlet vanes are controlled by placing a
static pressure sensor in the
downstream ductwork, typically about
two-thirds of the way down the longest
trunk duct. This sensor is set at a static
pressure that will ensure sufficient
pressure is available to move air from
that point through the remaining duct
work. The sensor will respond to duct
pressure changes and signal the inlet
vane operator to open or close the
vanes to maintain the control setting at
the sensor location.
As VAV terminal units begin to close in
response to a decreasing cooling load,
static pressure in the ductwork
increases. This causes the fan
operating point to temporarily move
upward to the left on a constant rpm
curve as shown in Figure A-5 (point A
to point B). The static pressure sensor
will detect an increase in duct pressure
and signal the inlet vane operator to
begin to close the vanes. The inlet
vanes will close until the static pressure
sensor is again satisfied, moving the
operation point to C (Figure A-5). As the
cooling load continues to decrease, the
modulation curve will be formed
(point C to D, and point D to E) on
Figure A-5. This curve passes through
the design point and through the static
pressure sensor control point. The
static pressure of any point on this
curve can be calculated using the
formula:
Sp = (Cfm/Cfm
SPd = static pressure at design,
= static pressure control setting,
SP
c
= cfm at design.
Cfm
d
Figure A-5 – VAV System Modulation Curve
)2 x (SPd-SPc) = SP
d
c
The VAV system modulation curve can
be drawn using a Trane system
modulation overlay. The axis of the
overlay is placed on a static pressure
control setting. The curve that
intersects the design points is the
system modulation curve.
Because the axes of the inlet vane
performance graph are in terms of
percent wide open cfm (wocfm)
and percent peak static pressure, the
first step in establishing the system
modulation curve is to find the
proper design points. By plotting the
design point on the performance
curve for the fan in question, one can
easily determine the percent wocfm.
Knowing this, plot a point on the
cfm-sp curve (Figure A-6) for inlet
vanes wide open, at the design point
of wocfm. By tracing to the left, one can
determine the percent of peak static
pressure. By knowing the design cfm,
static pressure and the percent of wide
open cfm and percent peak static that
these values represent, one can
calculate wocfm and peak static
pressure.
16
Application
Considerations
The control static pressure can then be
expressed as a percent of peak static
pressure and plotted. The system
modulation curve is described by the
curve on the modulation overlay that
passes through the design point when
the axis is placed on the control static
pressure point.
The minimum inlet vane cfm can easily
be determined after the system
modulation has been established. It
will be one of two things, either a) the
point where the system modulation
curve intersects the surge line, or
b) 40 percent wocfm, whichever is
greater. Forty percent wocfm is the
minimum point a Q fan with inlet vanes
can modulate, due to inherent
instability that results when the vanes
close to a certain angle.
A plot of part load cfm versus brake
horsepower can also be made after the
system modulation curve is established.
At each intersection of the system
modulation curve with a cfm-sp curve
for a certain inlet vane opening, a
vertical line is traced to the appropriate
bhp-cfm curve. At each intersection of a
bhp-cfm curve, a horizontal line is
traced to the scale of percent brake
horsepower. This will lead to a percent
wocfm versus percent peak bhp plot.
The design rpm and bhp need to be
corrected to account for performance
losses due to inlet vanes being in the air
stream. A correction of one percent to
the rpm and three percent to the bhp is
made in order to get to design
conditions with the inlet vanes fully
open.
Part load fan power consumption with
inlet vanes can be determined by
entering Figure A-6 at the desired
percent wide open cfm. (Wide open
cfm is found on the fan curve by
following the fan rpm to the right until
it intersects the 0” static pressure axis.)
Figure A-6 – Inlet Vane Performance
On Figure A-6, plot a system curve from
the control static pressure through the
point of operation defined as a
calculated percent wide open cfm. Read
vertically upward from the 25, 50 and 75
percent intersections to determine the
percent bhp at part load.
Intermediate operating points are found
by extrapolation. Inlet vanes increase
Q fan sound levels. See Table A-5.
17
Loading...