AMCA International AMCA International Technical Seminar 2009Technical Seminar 2009

Equipment VibrationEquipment Vibration

Presented by:Presented by:

Bill Howarth, Illinois Blower Inc.Bill Howarth, Illinois Blower Inc.

The Air Movement and Control The Air Movement and Control Association International (AMCA), has Association International (AMCA), has met the standards and requirements of met the standards and requirements of the Registered Continuing Education the Registered Continuing Education Providers Program. Credit earned on Providers Program. Credit earned on completion of this program will be completion of this program will be reported to the RCEPP. A certificate of reported to the RCEPP. A certificate of completion will be issued to each completion will be issued to each participant. As such, it does not include participant. As such, it does not include content that may be deemed or content that may be deemed or construed to be an approval or construed to be an approval or endorsement by NCEES or RCEPP.endorsement by NCEES or RCEPP.

Learning ObjectivesLearning Objectives

• Describe the distinction between balance and Describe the distinction between balance and vibrationvibration

• Know the levels of balance qualityKnow the levels of balance quality• Know the levels of installed vibrationKnow the levels of installed vibration• Understand the importance of an adequate Understand the importance of an adequate

foundationfoundation• Recognize symptoms and causes of problemsRecognize symptoms and causes of problems• Know how to avoid vibration problemsKnow how to avoid vibration problems

Equipment VibrationEquipment Vibration

Presented byPresented by

Bill HowarthBill Howarth

Hartzell Fan, Inc.Hartzell Fan, Inc.

ANSI / AMCA 204-96ANSI / AMCA 204-96

Balance Balance Quality and Quality and Vibration Vibration Levels for Levels for FansFans

•BalanceBalance

•VibrationVibration

BALANCEBALANCE

BalanceBalance•Synonymous with Unbalance. Synonymous with Unbalance.

A physical property results in A physical property results in centrifugal force being centrifugal force being applied to the fan impeller. applied to the fan impeller.

•Measured as the product of Measured as the product of unbalance mass and distance unbalance mass and distance from axis of rotation (oz-in).from axis of rotation (oz-in).

Center of Mass

Axis of Rotation

Shaft

Fan Impeller

UNBALANCEUNBALANCE

EXAMPLE:EXAMPLE:• ROTOR WEIGHT = ROTOR WEIGHT =

300 LBS300 LBS• RADIAL SEPARATION RADIAL SEPARATION

OF CENTER OF MASS OF CENTER OF MASS FROM AXIS OF FROM AXIS OF ROTATION=0.0052 ROTATION=0.0052 INCHES INCHES

• UNBALANCE =300 UNBALANCE =300 LBS * 16 OZ/LB LBS * 16 OZ/LB *0.0052 IN.*0.0052 IN.=25 OZ-IN.=25 OZ-IN.

UNBALANCEUNBALANCEA. Particulate builds up uniformly on the rotor.

B. A piece

of particulate flies off.C. Center of mass

shifts so that it no longer coincides with the axis of rotation.

Scrubber

Sticky-wet particulate

in gas stream

Fan

UNBALANCEUNBALANCE

200.0013

200.0000

= Displacement from axis of rotation = 0.36”Then Unbalance = (8500)*(16)*() = 49,000 oz-in

Dead spot 250F at top of

housing

120F at bottom of housing

Top of shaft = 188F

Bottom of shaft = 187F

250F

Fan wheel weight = 8500 lbs.Differential Expansion:

(188 - 187) * (6.5E-6in/in-F) * (200 in) = 0.0013 in

Shaft Bows Upward!

120F

UNBALANCEUNBALANCE

Dust accumulation inside hollow airfoil blade.

Rotat

i

on

UNBALANCEUNBALANCE

Buildup of dust on the backside of backward curves blades.

Rotat

i

on

UNBALANCEUNBALANCE

Hub

Shaft

Setscrews initially hold hub tightly in position on the shaft. Setscrew tips are corroded or worn by fretting over time. This allows the hub and entire fan wheel to be displaced relative to the axis of rotation causing unbalance.

Interference fit eliminates the possibility of the hub being displaced relative to the shaft in most systems.

EFFECT OFEFFECT OF TEMPERATURE TEMPERATURE

CHANGECHANGEFan impeller initially operating at 70 F.Process gas temperature increases rapidly.

Weld

Fan impeller and hub heat up more quickly than the shaft.

Integral hub and shaft for very rapid temperature change applications.

Conclusion: Conclusion: • Initial interference fit Initial interference fit

should be in excess of 0.002 should be in excess of 0.002 inches to allow for thermal inches to allow for thermal expansion plus an allowance expansion plus an allowance for hub expansion due to for hub expansion due to centrifugal force.centrifugal force.

Example: Example:

Shaft dia. = 3.9375 in.Shaft dia. = 3.9375 in.

Hub average temp = 215 FHub average temp = 215 F

Shaft average temp =80 FShaft average temp =80 F

Then hub growth relative to shaft:Then hub growth relative to shaft:

(3.9375) * (80) * (6.5E-6) = 0.002 in.(3.9375) * (80) * (6.5E-6) = 0.002 in.

Fan impeller weight = 250 lbs..Fan impeller weight = 250 lbs..

(250 lbs. x 16 oz/lb. x 0.002 inches)(250 lbs. x 16 oz/lb. x 0.002 inches)

Resulting unbalance = 8.0 oz-inchesResulting unbalance = 8.0 oz-inches

ANSI / AMCA 204, TABLE ANSI / AMCA 204, TABLE 4-14-1

Table 4-1 Fan Application Categories

APPLICATION EXAMPLESDRIVERPOWERkW (HP)LIMITS

FANAPPLICATIO

NCATEGORY,

BV

RESIDENTIAL Ceiling fans, attic fans,window AC

<= .15 (0.2)>.15 (0.2)

BV-1BV-2

HVAC &AGRICULTURAL

Building ventilation andair conditioning;commercial systems

<=3.7 (5.0)>3.7 (5.0)

BV-2BV-3

INDUSTRIALPROCESS& POWERGENERATION, ETC.

Baghouse, scrubber,mine, conveying, boilers,combustion air, pollutioncontrol, wind tunnels

<=300(400)

>300 (400)

BV-3BV-4

TRANSPORTATION &MARINE

Locomotives, trucks,automobiles

<= 15 (20)> 15 (20)

BV-3BV-4

TRANSIT/TUNNEL Subway emergencyventilation, tunnel fans,garage ventilation,Tunnel J et Fans

<=75 (100)> 75 (100)

ANY

BV-3BV-4BV-4

PETROCHEMICALPROCESS

Hazardous gases,process fans.

<= 37 (50)> 37(50)

BV-3BV-4

COMPUTER CHIPMANUFACTURE

Clean room ANY BV-5

ANSI / AMCA 204, TABLE ANSI / AMCA 204, TABLE 5-15-1Table 5-1

FANAPPLICATIONCATEGORY

BALANCE QUALITYGRADE

FOR RIGIDROTORS/IMPELLER

BV-1* G 16

BV-2 G 16

BV-3 G 6.3

BV-4 G 2.5

BV-5 G 1.0

*Note: In FAN APPLICATION CATEGORYBV-1 there may be some extremely smallfan rotors weighing less than 227 grams (8ounces). In such cases, residual unbalancemay be difficult to determine accurately.The fabrication process must ensurereasonably equal weight distribution aboutthe axis of rotation.

ANSI / AMCA 204, ANSI / AMCA 204, APPENDIX C.2APPENDIX C.2

VIBRATIONVIBRATION

VibrationVibration• The alternating mechanical motion The alternating mechanical motion

of an elastic system, components of of an elastic system, components of which are amplitude, frequency and which are amplitude, frequency and phase. phase.

• In general practice vibration values In general practice vibration values are reported as:are reported as:• Displacement - milsDisplacement - mils• Velocity - inches/secondVelocity - inches/second• Acceleration - peak g’sAcceleration - peak g’s

VIBRATION VIBRATION VELOCITYVELOCITY

1780 1780 RPMRPM

UUperper = 12.72 = 12.72 oz-inoz-in

Maximum Maximum VibrationVibration(in free space)(in free space)=2.5 mm/sec=2.5 mm/sec(or 0.10 in.sec)(or 0.10 in.sec)

VIBRATIONVIBRATION

Note that the Note that the bearing housing is bearing housing is considerably lower considerably lower than the expected than the expected vibration of the vibration of the rotor in free space.rotor in free space.

VibratiVibration on

PickupPickup

High High StiffneStiffness ss PedestPedestalal

MassivMassive e BearinBearing g HousinHousingg

Small Small Diameter, Diameter, Light RotorLight Rotor

SLEEVE BEARINGSLEEVE BEARINGProximity Probe Proximity Probe measures shaft measures shaft surface movement surface movement relative to the relative to the bearing housing.bearing housing.

Shaft Shaft (rotating)(rotating)

Bearing Bearing HousingHousing

Bearing Liner Bearing Liner (static)(static)

Oil Film Oil Film supports supports shaftshaft

EFFECT OF EFFECT OF STRUCTURESTRUCTURE

Fan Mass Mass

Circus FlagpoleAcrobat

Flagpole acts asa spring

Fn = 30 cyc/min

Cyclic Forces

Structural Steelacts as a springFn = 1200 cyc/minFan operating

speed = 1180RPM

Foundation

SOLID FOUNDATIONSOLID FOUNDATION

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

0 500 1000 1500 2000

Normal Normal Fn = 1680 Fn = 1680

cyc/mincyc/min

0.10 in/sec0.10 in/sec

11801180

Speed (RPM)Speed (RPM)

Fn >1.4 * FFn >1.4 * F

Operating Operating speed (F)speed (F)

Vibrati Vibrationon

(in/sec) (in/sec)

STRUCTURAL STEEL STRUCTURAL STEEL MOUNTINGMOUNTING

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

0 500 1000 1500 2000

Normal Normal Fn = 1200 Fn = 1200 cyc/mincyc/min

0.70 in/sec0.70 in/sec

11801180

Speed (RPM)Speed (RPM)

Operating Operating speed (F)speed (F)

Vibrati Vibrationon

(in/sec) (in/sec)

FLEXIBLE MOUNTFLEXIBLE MOUNTExpansion Expansion

JointJoint

Expansion Expansion JointJoint

Inlet

Duct

Discharge

Duct

Rigid Sub-BaseRigid Sub-Base(Often concrete (Often concrete filled)filled)

Spring Isolation with Spring Isolation with static deflection of 1.0 static deflection of 1.0 inchesinchesFn = 187.7/1Fn = 187.7/1.5.5 =187.7 =187.7 cyc/mincyc/min

Structural Structural Steel PlatformSteel Platform

ANSI / AMCA 204, TABLE ANSI / AMCA 204, TABLE 6-36-3

Table 6-3 Seismic Vibration Limits for Tests Conducted in the Factory

Values shown are peak velocity, mm/s (inches/s),Filter-In, at the factory test speed.

FANAPPLICATIONCATEGORY

RIGIDLYMOUNTEDmm/s (in./s)

FLEXIBLYMOUNTEDmm/s (in./s)

BV-1 12.7 (0.50) 15.2 (0.60)

BV-2 5.1 (0.20) 7.6 (0.30)

BV-3 3.8 (0.15) 5.1 (0.20)

BV-4 2.5 (0.10) 3.8 (0.15)

BV-5 2.0 (0.08) 2.5 (0.10)

VIBRATION UNITSVIBRATION UNITS

TRANSDUCER TRANSDUCER MOUNTINGMOUNTING

SWSI Centrifugal FansSWSI Centrifugal Fans

VerticalVertical

AxialAxial

HorizontalHorizontal

TRANSDUCER TRANSDUCER MOUNTINGMOUNTING

DWDI Centrifugal FansDWDI Centrifugal Fans

VerticalVertical

AxialAxial

HorizontalHorizontal

TRANSDUCER TRANSDUCER MOUNTINGMOUNTING

Axial FansAxial Fans

VerticVerticalal

AxialAxialHorizontHorizont

alal

VerticVerticalal

VIBRATION VIBRATION SPECTRUMSPECTRUM

0.000.00

0.050.05

0.100.10

0.150.15

0.200.20

00 500500 10001000 15001500 20002000 25002500

Filter Filter InIn

Speed Speed (RPM)(RPM)

Velocity Velocity (In./sec.) (In./sec.)

Filter Filter OutOut

ANSI / AMCA 204, TABLE ANSI / AMCA 204, TABLE 6-46-4

Table 6-4 Seismic Vibration Limits for Tests Conducted In-Situ

Values shown are peak velocity, mm/s (inches/s), Filter out.

Condition FanApplicationCategory

RigidlyMounted

mm/s (in./s)

FlexiblyMounted

mm/s (in./s)

Start-Up BV-1BV-2BV-3BV-4BV-5

14.0 (0.55)7.6 (0.30)6.4 (0.25)4.1 (0.16)2.5(0.10)

15.2 (0.60)12.7 (0.50)8.8 (0.35)6.4 (0.25)4.1 (0.16)

Alarm BV-1BV-2BV-3BV-4BV-5

15.2 (0.60)12.7 (0.50)102 (0.40)6.4 (0.25)5.7(0.20)

19.1 (0.75)19.1 (0.75)16.5 (0.65)10.2 (0.40)7.6 (0.30)

Shut-Down BV-1BV-2BV-3BV-4BV-5

NOTE 1NOTE 1

12.7 (0.50)10.2 (0.40)7.6 (0.30)

NOTE 1NOTE 1

17.8 (0.70)15.2 (0.60)10.2 (0.40)

Note 1: Shutdown levels for fans in FanApplication Grades BV1 and BV2 must beestablished based on historical data.

Questions?Questions?