04 vibration

7/28/2019 04 Vibration

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Reliability Management Consultant

Vibration StandardsVibration Standards

Condition AssessmentHow much vibration is too much?

Published Standards- ISO 2372 Manufacturers Guidelines

Comparison Trending


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ISO2372ISO2372

(A:Good, B:Rough, C: Still acceptable, D: Unacceptable)

Velocity(mm/s)

Peak RMS

Machine Classes

1.0

4.0

25.0

1.58

2.5

10.0

6.4

15.8

0.71

18.0

2.8

7.111.2

4.5

1.8

1.12

A

B

C

D

A

B

C

D

DD

C

C

B

B

AA

I II III IV


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Velocity (mm/s)Velocity (mm/s) Machine ClassesMachine Classes

PEAKPEAK RMSRMS II IIII IIIIII IVIV0.400.40 0.250.25

0.640.64 0.450.45

1.01.0 0.710.71

AA

AAAA

AA

CC

25.025.0

40.040.0

6464

18.018.0

2828

4545

DD

1.581.58 1.121.12

2.52.5 1.81.8

4.04.0 2.82.8 CC BB

BB

BB

6.46.4 4.54.5

10.010.0 7.17.1

15.815.8 11.211.2

CC

DD

DD

DD

CC BB

Good Usable Still Acceptable Unacceptable

Vibration Severity Ranges ISO 2372


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MACHINERY CLASSIFICATION INMACHINERY CLASSIFICATION IN

ACCORDANCE WITH ISO2372ACCORDANCE WITH ISO2372 CLASS I : Individual parts of engines and machines , IntegrallCLASS I : Individual parts of engines and machines , Integrallyy

connected with the complete machine in iconnected with the complete machine in its normalts normal

operating (Production electrical motorsoperating (Production electrical motors of up to 15KW )of up to 15KW )

CLASS II : Medium sized machines ,( typically electric motorsCLASS II : Medium sized machines ,( typically electric motorswith 15 to 75 KW out put) without speciwith 15 to 75 KW out put) without specialal

foundations , rigidly mounted engines ofoundations , rigidly mounted engines or machinesr machines

(up to 300 KW) on special foundations.(up to 300 KW) on special foundations.

CLASS III : Large prime movers and other large machinesCLASS III : Large prime movers and other large machineswith rotating masses mounted on rigid anwith rotating masses mounted on rigid and heavyd heavy

foundations which are relatively stifffoundations which are relatively stiffin thein the

direction of vibration measurement.direction of vibration measurement.

CLASS IV : Large prime movers and other large machines withCLASS IV : Large prime movers and other large machines with

rotating masses mounted on foundations wrotating masses mounted on foundations which arehich are

relatively soft in the direction of vibrelatively soft in the direction of vibrationration

measurement (e.g. turbo generator sets,measurement (e.g. turbo generator sets, especiallyespeciallythose with light weight substructures).those with light weight substructures).


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RECIPROCATING MACHINESRECIPROCATING MACHINES

CLASS V & VI belongs to reciprocatingCLASS V & VI belongs to reciprocatingmachines on hard & soft foundations.machines on hard & soft foundations.

For reciprocating machines ISO have given noFor reciprocating machines ISO have given nostandard & indicate that it should be eitherstandard & indicate that it should be eitherbased on trend or one should be governed bybased on trend or one should be governed by

the manufacturer.the manufacturer. Reciprocating machines need balancing ofReciprocating machines need balancing of

rotating as well as reciprocating masses asrotating as well as reciprocating masses aswell.well.

On Diesel Engines 500KW plus it is notOn Diesel Engines 500KW plus it is notunusual to see vibration as high as 25unusual to see vibration as high as 25--40mm/sec.40mm/sec.

Trending is normally recommended onTrending is normally recommended onreciprocating machines.reciprocating machines.


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R li bilit M t C lt t


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Reliabilit Management Cons ltant


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Trend MonitoringTrend Monitoring



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TRENDING OVERALL READINGS

The most efficient and reliable method of evaluatingvibration severity is to compare the most recent overall

reading against previous readings for the samemeasurement, to see how the measurements vibrationvalues are changing, trendingover time.

This trend comparison between present and pastreadings is easier to analyze when the values are plottedin a trend plot.

A trend plot is a line graph that displays current and pastoverall values plotted over time.



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TRENDING OVERALL READINGS

Past values should include a base-line (known good)reading.

The base-line value may be acquired after an overhaul orwhen other indicators show that the machine is runningwell.

Subsequent measurements are compared to the base-line to determine machinery changes.



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How do we set the limits?How do we set the limits?

Baseline = V, G, DBaseline = V, G, D Warning = 1.5 x Y mm/s; 10 G;Warning = 1.5 x Y mm/s; 10 G;

1.5 D1.5 D Alarm = 5 to 7 x Y mm/s;30Alarm = 5 to 7 x Y mm/s;30--50G,50G,

4/5D4/5D

Warning and Alarm Limits

04 vibration

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