VAVFA

NS

VariableAirVolumeVane Axial Fans

CHICAGO BLOWER CORPORATION • GLENDALE HEIGHTS, ILLINOIS • USA

BULLETIN VAV 107

D/47VaneAxialFans

Chicago’s Design 47 Vane Axial fans are specifiedby architects, engineers and industrial firms world-wide to meet today’s environmental challenges.Chicago fans are selected for internationallyrenowned installations such as the Sidney OperaHouse, Petronas Twin Towers and United’s O’HareTerminal. Vane axial fans are chosen for their relia-bility, low initial cost and space saving configuration.Chicago’s variable air volume fans provide maximumefficiency even in unpredictable environments. Twotypes of Chicago D/47 Vane Axial direct drive fansare offered, Controllable Pitch and Adjustable Pitch.Both supply volumes to 250,000 cfm, pressures to15 sp. and sizes to 81-1/8".

Chicago Blower fans are recog-nized for their reliability andindustrial quality. Every phase offan construction is governed bystrict Chicago guidelines andstringent AMCA requirements.For application evaluations and fan recommenda-tions, contact a Chicago Blower representative.

Controllable PitchControllable Pitch fans respond automatically tochanges in temperature, humidity, air flow, gas con-centration and air quality. Clearly the best choice forvariable air volume systems, they are also used insensitive industrial applications to maintain constantconditions regardless of air demand.

Adjustable PitchAdjustable Pitch fans are specified for applicationsless critical to environmental variations, typicallyseasonal changes or system expansion. Blade pitchis adjusted externally at the hub to increase or de-crease volume and pressure.

Chicago Blower certifies that theDesign 47 Fans shown herein arelicensed to bear the AMCA Seal.The ratings are based on testsand procedures performed in ac-cordance with AMCA Publication211 and comply with the require-ments of the AMCA Certified Rat-ings Program.

2 Cover photo by Carol M. Highsmith

Optional Equipment

Streamlined Inlet BellAn inlet bell reduces entry loss and isnecessary to obtain rated performanceon open inlets.The inlet bell, or a casingextension, must be used with Control-lable pitch fans. Heavy gauge spinningbolts to inlet flange, but is not designedto support the fan.

Inlet or Outlet ConeSince a vaneaxial fan can have a diam-eter about 20% smaller than the duct, atapered cone is used to connect with ei-ther the inlet or outlet. An inlet cone mayalso be used on open fans to avoidlarge velocity pressure loss. Theflanged, punched cone bolts to fan andduct and will support fan in any positionexcept cantilever.

Access DoorThe access door is located in the op-tional inlet/outlet cone to facilitate bladeinspection, adjustment or cleaning. Thedoors are gasketed and are sealed air-tight with quick release latches.

Spool PieceA non-tapered housing extension com-plete with latched door is used in instal-lations where an access door cannot beprovided in the duct.

Guard ScreenHeavy gauge wire screen protects fanblades from foreign debris. It fits fanflange, inlet or outlet cone, or inlet bell.

For Both Adjustable Pitch andControllable Pitch Fans

CompanionAngle RingsAngle rings facilitate installationwith both flexible and slip-fit con-nections.

Mounting FeetHeavy reinforced steel plate welded tothe fan housing is suitable for floor orceiling mounting.

Vibration IsolatorsSpring type and elastomer in-shear rub-ber or neoprene mounts reduce vibra-tion transmission in any fan mountingposition.

Sound AttenuatorAttenuator reduces sound levels innoise sensitive applications. It bolts tofan inlet or outlet. Acoustical cones areavailable in lieu of standard cones.

Variable Inlet VanesManually adjusted vanes are used tovary volume when frequency changesare required. Assembly bolts to fanflange.

Electric Option includes an electric/pneumatic transducer to translateuser electric signals to the pneumatic signals required by the pilotpositioner.

Compressed air for the Electric Option is furnished either by the useror by an auxiliary pneumatic power pressure system available fromChicago Blower. The auxiliary system consists of an air compres-sor, receiver, gauges, filters, drains and air lines. It is either mountedto the fan casing or furnished loose for user mounting.

Automatic Electric ControlFor Controllable Pitch Fans

3

Controllable Pitch Fanshown with optional mountingfeet. Casing extension withmotor tie supports is standardfor large NEMA frame motors.

4

Fan Selection GuidelinesAltitude and Temperature Correction Factors

Design 47 fans were tested and rated onthe basis of handling air at standard den-sity of .075 lb./ft.3..

In order to select a fan for operation atany other temperature or altitude, it isnecessary to correct the pressure fromoperating density to standard density, se-lect the fan, then correct the requiredhorsepower from standard to operatingconditions.

The correction factor chart below givesthe ratio of actual to standard densitiesat various temperatures and altitudes.Apply the factors as follows:

Ps Standard = Ps Actual ÷ Factor;BHP Actual = BHP Standard x Factor

For Example

Required Duty: 30,000 CFM at 1.58" Ps

at 120°F at 4000' elevation

From chart below: Factor is .790

1.58 Actual ÷ .790 = 2.0" Ps Standard

Select fan model from selection chart:

4450 - B12 - 1160

BHP at Standard = 14.6

BHP at Operating Conditions = 14.6 x

.790 = 11.53

Changes in volume, pressure, and horsepower occur in ac-cordance with the fan laws when fan speed and/or gas den-sity changes while the fan is applied to a fixed system.Whenoperating density is other than standard (.75#/ft.3), pressuremust be corrected to standard conditions for fan selectionand horsepower must be corrected from standard to operat-ing conditions as in the example above. Performance may beadjusted according to the fan laws by changing fan speed.

Basic Fan Laws

5

Total Pressure ConceptChicago Blower Design 47 perform-ance is published in terms of TotalPressure.Total Pressure = Static Pres-sure + Velocity Pressure

“Static Pressure” is unrelated to airmotion. It is a pressure that exerts aforce equal in all directions, like the airpressure in a balloon or pressure ves-sel, and can be Positive or Negative.

“Velocity Pressure” is the kinetic en-

ergy applied to motion or speed of the

air through a duct system. It is always

Positive in character.

A fan “sees” only Total Pressure. It can-

not recognize Static or Velocity Pres-

sure as separate quantities.Therefore,

the “Total Pressure Concept” must be

considered to assure that any variation

in the actual installation from the in-

stallation in which the fan was tested

is accounted for.

A fan is normally tested blowing into a

duct of the same cross-sectional area

as the fan outlet. When it is rated on

Static Pressure, the rating is based on

Total Pressure minusVelocity Pressure

in the test duct. The rating is only valid

if the fan is installed similar to the test

setup. If it is not, the true Static Pres-

sure capability will be greater or less

than the rated Static Pressure.The dif-

ference will be the difference between

actual Velocity Pressure and theVeloc-

ity Pressure based on the fan area.

Cones may be used to transition from

the fan to ducts larger or smaller than

the fan.Outlet cones may also be used

to minimize Velocity Pressure loss and

regain Static pressure. Air leaves a di-

verging discharge cone (Point B) at a

lower velocity than at the cone inlet

(Point A), therefore, at a lower Velocity

Pressure. Consequently, more of the

fan’s Total Pressure capability is avail-

able for Static Pressure than would be

For the Standard VAV cone effectivePv is: PvE = PvA - (PvA - PvB) .8

Where a cone is used, the rated StaticPressure is increased by the amountequal to PvE - PvB.

Use of Outlet or Inlet Cone

AIRFLOW

FAN

PV APV B

CONEA B

Where the fan has an open discharge

(does not blow into a cone, duct or

transition), the Velocity Pressure must

be based on the annular area; that is,

the fan casing area minus the hub

area. Since annulus velocity is gener-

ally very high, the benefit of using a

cone when discharging to atmosphere

is apparent.

Note: AMCA certified ratings do not apply

when factors are used.

available with the fan blowing into a

duct of diameter equal to the fan.

FanAreas(Ft2)

165018252000

222524502700

300033003650

402544504900

542560006650

73008112

1.481.822.18

2.703.273.98

4.915.947.27

8.8410.8013.10

16.0519.6324.12

29.0735.89

2.182.703.27

3.984.915.94

7.278.8410.80

13.1016.0519.63

24.1229.0735.89

44.1754.54

0.661.001.36

1.882.453.16

4.095.126.45

–––

–––

––

–––

–1.452.16

3.094.125.45

7.028.9811.28

14.23––

––

–––

–––

–––

5.507.469.76

12.71––

––

–––

–––

––3.22

4.796.759.05

12.0015.5820.07

25.0231.84

FAN SIZECASINGAREA

CONEAREA HUB A HUB B HUB LB HUB C

ANNULAR AREAS

Velocity Pressure = –––––––––––––Fan Area x 4005

where Fan Area = cross sectional areaat the flow point considered

CFM( )2

6

*d = 1.326 x Pb°F + 460

Pt = Ps + Pv

2 2*Pv = Q = V

A x 4005 4005

Fan BHP = Q x Pt = Q x Ps6362 x nt 6362 x ns

For 3 phase motors: BHP output =E x I x ME x Pf x 1.73

746

For 3 phase motors: Kw input =E x I x Pf x 1.73

1000

For 1 phase motors: BHP output = E x I x ME x Pf746

For 1 phase motors: Kw input =E x I x Pf1000

To plot a System Curve where Ps1 and Q1 are known, usethe following formula to find other curve points:

Ps 2 = Ps1Q 2

2

Q 1

To determine round duct equivalent of rectangular duct forsame friction loss and volumetric capacity:

DR = 1.2655 (ab)3

a + b

* Formulas for d and Pv are applicable to dry air only.

( ( ( (

( (

Symbol Definition

A area (ft.2)a side a of rectangular ductb side b of rectangular duct

BHP brake horsepowerQ air volume flow (ft.3/min.)d air density (lb/ft.3)DR diameter of round ductE volts°F temperature (Fahrenheit)I amps

KW kilowattsME motor efficiency (dec.)ns fan static efficiency (dec.)nt fan total efficiency (dec.)Pb barometric pressure

(inches mercury)

Pf power factorPs static pressure

(inches WG)

Pt total pressure (inches WG)Pv velocity pressure

(inches WG)

V velocity (ft./min)

Fan Application Formulas

FanSoundData

Chicago Blower design 47 Vane AxialFans have been carefully noise tested inaccordance with AMCA Standard TestCode No. 300 for sound Rating of AirMoving Devices. Certified Sound Ratingdata is available upon request.

Sound data is as complete as it is possi-ble to provide. It permits the engineer tocompare noise levels accurately withother fans if they are also accuratelytested and rated according to the AMCACode. It permits the engineer to deter-

mine dB A levels quickly without calcula-tion, and provides the information neededto determine dBA levels for specific instal-lations.

For applications requiring lowest noise lev-els, Chicago Blower has attenuators avail-able designed specifically for Design 47characteristics. Vane Axial fans are easierand less costly to attenuate than Centrifu-gal fans. An attenuated Design 47 fan canprovide lowest noise levels at low costwithin the building space.

7

EngineeringSpecifications

General:Provide variable volume vaneaxial fans asshown on the drawings of the capacities andtype as shown on the fan schedule. All fansshall be licensed to bear the AMCA Certi-fied Rating Seal for Air Performance andSound Power Level. Acceptable vendorsare: Chicago Blower Corporation.

Housings:Fan housings are to be precisely formed withintegral rolled flanges on inlet and outlet.Housings shall be mechanically expanded toinsure concentricity. Fans 36-1/2" diameterand smaller shall be made from not less than7 ga. thickness metal. Fans 40-1/4" diame-ter and larger shall be made from not lessthan 1/4" thick metal. Housings shall includenot less than 9 stationary guidevanes, innerfairing, and motor bulkhead to receive aNEMA “C”-face, flange mounted, TEAOelectric motor. Motor mounting plates willvary in thickness, but will not be less than thefollowing:

Motor mounting plates will be fabricated sothe bolts holding the C-face motor are not inshear. and if the motor is removed it can bereplaced in the original location without theuse of shims or ancillary centering devices.

Rotors:Fan blades are to be cast from A356-T51aluminum alloy. Blades shall be airfoilshaped for maximum efficiency and twistedfrom hub to tip to obtain equal air distribu-tion along the blade. Blade and shank are tobe cast integral to insure maximum bladeintegrity. Blade shall have an index markcast into the skirt for setting position ofblade. To insure wheel integrity, the methodof retaining the blade in the hub and themethod for holding the blade at the properpitch shall be separate, so the blade retain-ing mechanism is not affected by blade ad-justments. Hubs are to be one piece, castfrom A356-T6 aluminum alloy. Each bladesocket in the hub shall have vernier to beused in conjunction with blade index markfor accurately setting angle of attack of blade.

Aluminum Castings:1. Chemical verification of virgin metal shallbe provided. Chemistry of the aluminumshall be checked during the course of aheat and adjustments made as necessary.

2. Test bars shall be pored at the start andfinish of each heat.Test bars shall be sub-mitted to a qualified test laboratory for con-firmation of proper mechanical propertiesof castings. Failure of test bars will causerejection of castings made from that heat.

3. All castings will be visually inspected forobvious flaws and workmanship.

4. Since identification of cracks is importantto the integrity of castings and cracks can-not be properly identified by radiographicinspection, all casting lots shall undergosample liquid penetrant examination.Suchexamination shall be made in an approvedlaboratory by personnel qualified and cer-tified in accordance with SNT-TC-1A (Pro-cedure Qualification and Certification ofNon-Destruction Testing). Casting lots fail-ing this inspection will be rejected.

5. After castings are penetrant tested, sam-ples shall be radiographically inspected.Radiographic samples and acceptance/re-jection criteria shall conform to AluminumAssociation Standard AA-CS-M5-85.Rejection of samples will cause rejectionof entire heat.

Controllable PitchAssembly:For decreased maintenance, assembly willinclude permanently lubricated ball thrustbearings for each blade.Compatibility of turndown to zero flow shall be required when in-dicated. Loss of control signal or de-energiz-ing fan will cause blades to rotate to minimumflow position.

Actuator consists of pneumatic piston withspring return mounted integrally and rotatingwith rotor assembly. Supply air is 80 PSIand is transferred to piston by a rotatingunion. Pilot positioner, suitable for 3-15 PSIcontrol signal, is mounted externally andfeedback signal is provided by cable con-nection to piston.

A Hub B Hub C Hub3/8" 3/4" 1"

8

TOTALPRESSURE

CF

Optimum Efficiency Selection Chart

A) Enter the chart with the specified volumeand static pressure to find the most efficientselection.

B) Since the chart is based on total pressure,the velocity pressure must be determinedfor the fan selected in A above and addedto the static pressure to arrive at a totalpressure.Velocity pressure is determined bythe following formula

The fan areas are on page 5.

VP = ( Fan Area x 4005 )2CFM

EXAMPLE: 40,000 CFM at 4.0" SP

A) Enter the chart with 40,000 CFM and4.0" SP. Entry falls into 80% efficiencyarea for a Model 4450-B6-1760.

B) Determine TP -TP = SP + VPTP = 4.0 = .86 = 4.86

VP = ( 10.8 x 4005 )2= .8640,000

Refer to Chicago Blower’sfan.net selection programfor performance fan curvesand sound data.

Contact your localChicago Blower salesengineer for softwareand assistance

EXAMPLE: MODEL 4450-B6-1760

The model number indicates the following:

Fan Diameter = 44-1/2"Hub Series = BNumber of Blades = 6Fan Speed = 1760 RPM

VAV FanModel

Numbers

I

This chart presents a general selection method for Chicago BlowerVAV Vaneaxial Fans.All fans se-lected from this chart should be checked for exact horsepower and operating characteristics by con-sulting the individual fan curve for that selection.

USING THE SELECTION CHART

C) Re-enter the chart with 40,000 CFMand 4.86 TP. The selection remains4450-B6-1760.

Determine approximate HP

HP = CFM x TP = 40,000 x 4.86 = 38

6362 x eff 6362 x .8

C) Re-enter the chart with the specified volumeand calculated total pressure to verify youroriginal selection.

D) Approximate horsepower of the selected fanmay be determined by using the chart effi-ciency for the selected fan in the followingformula:

E) Refer to the individual fan curve for exactBHP and possible energy savings by utiliz-ing a diverging outlet cone.

HP =6362 x eff

CFM x TP

The following information is rChicago Blower Design 47 Vamation must be complete to as

TOTALPRESSURE

9

FM (X 1000)

15

10

9

8

7

6

5

4

3

2.5

2

1.5

1.0

.9

.8

.7

.6

.5

.4

.3

3 4 5 6 7 8 9 10 15 20 25 30 40 50 60 70 80 90 100 150 200

Dark Shading - 80% Efficiency

Light Shading - 75 - 80% Efficiency

Unshaded - 70-75% Efficiency

OrderingInformation

a. At what density required pressurevalue is measured.

b. At what other density, if any, fan willbe expected to operate.

5. Motor Characteristics: HP, RPM, Volts, Phase,Hertz, enclosure if other than TEAO required.

6. Accessories required.

1. Fan Size, Model Number and RPM

2. Fan Duty Requirements: CFM, Total orStatic Pressure, Gas Density, Gas Com-position (if not clean air), Maximum Tem-perature, Normal Operating Pressure.

4. Where operating density is other than.075#/ft.3 : state

required when ordering aane Axial Fan. This infor-ssure proper performance.

5425C121760

5425C61760

5425B121760

5425LB121160

5425B121160

5425B12890

5425B12890

5425-B

6-890

7300-B

6-690

4900-B

6-890

4900-B

6-890

3650-A12-890

3650-A6-890

3300-A6-890

4450C1217604025

C121760

5425LB121760

5425LB121760

6000C121760

6650C121160

6650C61160

6650C12890

6650C6 890

6650C12690

6650C6 690

6650C6 890

6000C12690

6000C121160

4900B121760

4900LB12 1760

4900LB12 1760

4900B61760

4900B121160

4900LB121160

4900B1211604900

B61160

4900B6 890

4900B6 890

4450B6 890

3650A121160

3650A61160

3650A61760

3650A61760

3650A121760

3650B121760

4025B61160

3300A12890

3300A6890

3300A61160

3300A121160

3300A61760

3300A121760

3300A121760

3300B121760

3300B121760

3000A6890

3000A6890

3000A12890

3000A121160

3000A121160

3000A121760

3000A121760

3000A61760

3000A121760

2700B123500

2700A63500

2700A121160

2700A123500

2700A12890

2700A6890

2700A6890

2450A121160

2450A61760

2450A121760

2450A63500

2450B121760

2225A121760

2225A121760

2225A61760

2225A1211602225

A121160

2000A61760

2000A121760

2225A61160

2450A123500

2450B63500

1825A63500

1650A123500

1650A63500

1825A121760

2450B123500

2450A61160 2700

A61160

2700A61160

2700B121760

2700A61760

2700A121760

2700A121760

3650C121760

3650A12890

4450B12890

4450B61160

4450B121160

4450B121160

4450B61760

4025B121760

4025B121760

4025B61760

4025B121160

4025B121160

4025B12890

4450B121760

6000C61760

6000C12890

7300C61160

6000C61160

CFM (X 1000)

7300C121160

7300C121160

8112C121160

8112C121160

8112C611608112

C12890

7300C12690

7300C12690

7300C6890

7300C6690

8112C6690

8112C12690

8112C12690

7300C12890

10

Figure 1

To properly compare various methods ofvolume control, you need to look furtherthan just brake horsepower savings.Own-ers do not pay for brake horsepower, theypay for electricity consumed (input power).Inefficiencies in powered equipmentshould be included in any comparison ofvolume control methods. Figure 1 depictsthe power consumption of various typesof volume control apparatus applied to afan operating on a normal system curvewhere the required pressure varies as thesquare of the volume of air). The blue linedepicts the system brake horsepower re-quirements as a percentage of the fullload requirement. The other lines depictthe input power requirements for the var-ious types of volume control when appliedto this system in conjunction with a 90%efficient motor.

1. The green line indicates the inputpower required for a controllable pitchVAV Vane axial fan. Note at full load,since we are using a 90% efficientmotor, the input power requirement isgreater than 100%.

2. The orange line indicates the inputpower required when applying an ad-justable frequency speed controller tothe same fan (published data frommanufacturer of adjustable frequencyspeed controller). Note at full load, theinput power requirement is greaterdue to inefficiencies in both motor andspeed controller.

3.The red line depicts the input power re-quired for the same fan utilizing aninlet vane control damper.

Note that until you exceed 50% turn-down, the Controllable Pitch fan requiresless power than the adjustable frequencyspeed controller. This is due to theinefficiencies in the frequency controlapparatus.

At 80% of full load flow, the controllablepitch fan consumes 15% less power thanthe adjustable frequency and 39% lessthan a variable inlet vane control.

At 70% of full load, the controllable pitchfan consumes 10% less power than the

Compare theEfficiency of a

ControllablePitch Fan

Controllable Pitch Fan Blades

Blade angle can beadjusted while fan isoperating... providespower savings

11

Figure 2

Figure 3

Figure 4

adjustable frequency and even as low as60% of full load, the savings is 5%.

It should be noted that since most vari-able volume systems operate at their de-sign point only a few hours per year,it iscommon, and good practice to select thecontrollable pitch fan to the right of itsmost efficient operating area. As the sys-tem turns down, the fan will run in the nor-mal system operating range at a highefficiency level.

Also, most variable volume systems havefixed resistances that do not vary with thevolume of air being supplied. When thesystem requires a high turn down, caremust be taken in fan selection when ad-justable speed control is used so the fanis not forced into an unstable operatingpoint at low air flow.

The most common use of the controllablepitch fan is on the system curve where thesystem pressure varies as the square ofthe volume. Figure 2 indicates such a sys-tem. The orange line indicates horse-power consumed as the fan operatesalong the system. Note the selection wasmade so the design point is to the right ofthe most efficient operating area so thateven at 75% of flow, the fan will operate atequal or higher efficiency than it does atthe design flow.

With a controllable pitch fan, you are notlimited to operating on the system asnoted above. Figure 3 indicates the oper-ation of controllable pitch fan constantstatic pressure system. With the fan de-picted, you can operate on a constantstatic pressure down to 25% of the designflow. Since the system pressure remainsconstant, the horsepower savings are notas great as for Figure 2, but still amount toa substantial energy savings.

You can also apply the controllable pitchfan to a system when a constant volumeof air is required at varying pressures. Fig-ure 4 is representative of this type of sys-tem and indicates the energy that can besaved by using the controllable pitch fan.

12

Adjustable Pitch Vane Axial Fan Arrangement 4

13

Controllable Pitch Vane Axial Fan Arrangement 4

14

Accessories Vane Axial Fan Arrangement 4

Horizontal - Floor Mounted Mounting Feet

Horizontal - Lug Mounted

Vertical - Lug Mounted

Inlet/Outlet Cone

Inlet Bell CasingExtension

15