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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?