1. Transient Vibration Analysis- Insights into Machinery Behavior
By Stanley R. Bognatz, P.E.
75 Laurel Street, Carbondale, PA
Tel. (570)
13 Aberdeen Way
Elgin, SC 29045
Tel. (803)
Integrally Geared Centrifugal Air Compressor Vibration Analysis Case Studies 15-Feb-2008
By: Timothy S. Irwin, P.E. Senior Engineer
Rotating Machinery Diagnostics & Instrumentation Solutions for… “Maintenance That Matters”
M&B Engineered Solutions, Inc., 2007

2. Integrally Geared Air Compressors
Transient Vibration Analysis-
Insights into Machinery Behavior
By Stanley R. Bognatz, P.E.
75 Laurel Street, Carbondale, PA
Tel. (570)
Integrally Geared Air Compressors
How many of you have a Joy, (now Cameron) I-R Centac, Elliott PAP, Clark (Dresser-Rand) Isopac
There are some differences in their designs, but there are more similarities especially for PdM monitoring and vibration/condition analysis
© 2008 M&B Engineered Solutions, Inc.
Integrally Geared Air Compressor Case Studies
Vibration Institute Piedmont Chapter Meeting
Augusta, GA 15-Feb-2008
M&B Engineered Solutions, Inc., 2007

3. Integrally Geared Air Compressors
Transient Vibration Analysis-
Insights into Machinery Behavior
By Stanley R. Bognatz, P.E.
75 Laurel Street, Carbondale, PA
Tel. (570)
Integrally Geared Air Compressors
How do we monitor these types of machines?
What kind of components are we trying to monitor in these machines?
High speed gearing
High speed shafts / impellers
Low speed shafts
Geared couplings
Disc or shim-pack couplings
Sleeve bearings
Multi-segment tilt pad bearings
This does not include the driver which could be a motor or turbine of which
either one can add more complexities to the setup of a monitoring route
© 2008 M&B Engineered Solutions, Inc.
Integrally Geared Air Compressor Case Studies
Vibration Institute Piedmont Chapter Meeting
Augusta, GA 15-Feb-2008
M&B Engineered Solutions, Inc., 2007

4. Integrally Geared Air Compressors
Transient Vibration Analysis-
Insights into Machinery Behavior
By Stanley R. Bognatz, P.E.
75 Laurel Street, Carbondale, PA
Tel. (570)
Integrally Geared Air Compressors
What parameters do we have available for monitoring the overall condition?
Bearing temperatures
Stage and drive gear vibration
Stage inlet and outlet temperatures
Stage inlet and outlet pressures
Intercooler inlet and outlet temperatures
Intercooler inlet and outlet pressures
Motor amperage or kW
There are a lot of parameters that can be used including the above items and:
Performance testing
Oil Analysis
And visual inspections
There are a lot of things to look at for an overall condition.
Changes in any of the above items can be a significant indicator of the changing condition of the machine with clues as to what happened
© 2008 M&B Engineered Solutions, Inc.
Integrally Geared Air Compressor Case Studies
Vibration Institute Piedmont Chapter Meeting
Augusta, GA 15-Feb-2008
M&B Engineered Solutions, Inc., 2007

5. Integrally Geared Air Compressors
Transient Vibration Analysis-
Insights into Machinery Behavior
By Stanley R. Bognatz, P.E.
75 Laurel Street, Carbondale, PA
Tel. (570)
Integrally Geared Air Compressors
What do we use to monitor the vibration of the machine?
Is there a permanent probe of some kind on each stage?
Is there a permanent monitoring / vibration protection system installed?
Or are our only options temporary accelerometers?
Many permanent monitoring systems will have proximity probes on each stage,
are they?
A single probe on the stage?
Dual probes at 90 degrees?
Any there permanent accelerometers?
Can you ‘plug-in’ to obtain the raw signal in your portable data collector?
Many Metrix proximity transmitters do have a test connection
There are a lot of considerations to obtaining the most effective data that you can use
Find out what you have and use what you can.
© 2008 M&B Engineered Solutions, Inc.
Integrally Geared Air Compressor Case Studies
Vibration Institute Piedmont Chapter Meeting
Augusta, GA 15-Feb-2008
M&B Engineered Solutions, Inc., 2007

6. Integrally Geared Air Compressors
Transient Vibration Analysis-
Insights into Machinery Behavior
By Stanley R. Bognatz, P.E.
75 Laurel Street, Carbondale, PA
Tel. (570)
Integrally Geared Air Compressors
Vibration Analysis:
Proximity probe use
Magnetically mounted accelerometers
High Frequency accelerometers
To use the above probes we need to figure out the expected fault frequencies
So that we can set up the appropriate frequency spans and resolutions
The following segments of the case studies will be on several
Joy (Cameron Compression) MSG 4-stage machines
For today’s discussion lets take a closer look at the vibration analysis of one of these compressors
Lets look at an example compressor
© 2008 M&B Engineered Solutions, Inc.
Integrally Geared Air Compressor Case Studies
Vibration Institute Piedmont Chapter Meeting
Augusta, GA 15-Feb-2008
M&B Engineered Solutions, Inc., 2007

7. Case Study #1 – Cameron Compression MSG
Transient Vibration Analysis-
Insights into Machinery Behavior
By Stanley R. Bognatz, P.E.
75 Laurel Street, Carbondale, PA
Tel. (570)
Case Study #1 – Cameron Compression MSG
What are typical Fault Frequencies:
Shaft Running Speeds
Journal Bearing Issues
Gear Mesh (and other gear fault frequencies)
Vane Pass (diffuser vs. impeller)
Coupling/Alignment
Motor
Shaft Running Speeds
Journal Bearing Issues
Electrical Frequencies
These are jus the general items
© 2008 M&B Engineered Solutions, Inc.
Integrally Geared Air Compressor Case Studies
Vibration Institute Piedmont Chapter Meeting
Augusta, GA 15-Feb-2008
M&B Engineered Solutions, Inc., 2007

8. Case Study #1 – Cameron Compression MSG
Transient Vibration Analysis-
Insights into Machinery Behavior
By Stanley R. Bognatz, P.E.
75 Laurel Street, Carbondale, PA
Tel. (570)
Case Study #1 – Cameron Compression MSG
Example Fault Frequencies:
Shaft Speeds:
Motor, Couplings, & Gear – 1781 rpm
Pinion Speeds – 14,385 & 21,372 rpm
Gears (420 teeth, 52 teeth, 35 teeth):
Gear Mesh – 748,020 (12,467 Hz)
Assembly phase – 187,000 & 21,372 cpm
Hunting Tooth – 1198, 203 cpm
Vane Pass – 362,100 cpm (for bladed diffuser)
Lets look at a few of these numbers for a general idea of the ranges that we have to work in.
So remember, you may have to take multiple data sets, be prepared to do high frequency analysis
© 2008 M&B Engineered Solutions, Inc.
Integrally Geared Air Compressor Case Studies
Vibration Institute Piedmont Chapter Meeting
Augusta, GA 15-Feb-2008
M&B Engineered Solutions, Inc., 2007

9. Case Study #1 – Cameron Compression MSG
Transient Vibration Analysis-
Insights into Machinery Behavior
By Stanley R. Bognatz, P.E.
75 Laurel Street, Carbondale, PA
Tel. (570)
Case Study #1 – Cameron Compression MSG
Displacement – Velocity – Acceleration
What is an acceptable measurementfrequency range:
3600 rpm 20,000 rpm 750,000 cpm
Displacement (mils)
Velocity (in/s)
Acceleration (g)
3600 rpm 20,000 rpm 750,000 cpm
Displacement (mils)
Velocity (in/s)
Acceleration (g)
© 2008 M&B Engineered Solutions, Inc.
Integrally Geared Air Compressor Case Studies
Vibration Institute Piedmont Chapter Meeting
Augusta, GA 15-Feb-2008
M&B Engineered Solutions, Inc., 2007

10. Case Study #1 – Cameron Compression MSG
Transient Vibration Analysis-
Insights into Machinery Behavior
By Stanley R. Bognatz, P.E.
75 Laurel Street, Carbondale, PA
Tel. (570)
Case Study #1 – Cameron Compression MSG
Lets look at some trends and stuff that you might see:
Within 2 weeks after starting a machine after a major refurbishment:
Note the step changes in the trend plot
© 2008 M&B Engineered Solutions, Inc.
Integrally Geared Air Compressor Case Studies
Vibration Institute Piedmont Chapter Meeting
Augusta, GA 15-Feb-2008
M&B Engineered Solutions, Inc., 2007

11. Case Study #1 – Cameron Compression MSG
Transient Vibration Analysis-
Insights into Machinery Behavior
By Stanley R. Bognatz, P.E.
75 Laurel Street, Carbondale, PA
Tel. (570)
Case Study #1 – Cameron Compression MSG
Here is one year’s worth of trend from that stage:
Note the variations in amplitude over time
© 2008 M&B Engineered Solutions, Inc.
Integrally Geared Air Compressor Case Studies
Vibration Institute Piedmont Chapter Meeting
Augusta, GA 15-Feb-2008
M&B Engineered Solutions, Inc., 2007

12. Case Study #1 – Cameron Compression MSG
Transient Vibration Analysis-
Insights into Machinery Behavior
By Stanley R. Bognatz, P.E.
75 Laurel Street, Carbondale, PA
Tel. (570)
Case Study #1 – Cameron Compression MSG
Here is a recent comparison to the other stages on the same machine
© 2008 M&B Engineered Solutions, Inc.
Integrally Geared Air Compressor Case Studies
Vibration Institute Piedmont Chapter Meeting
Augusta, GA 15-Feb-2008
M&B Engineered Solutions, Inc., 2007

13. Case Study #1 – Cameron Compression MSG
Transient Vibration Analysis-
Insights into Machinery Behavior
By Stanley R. Bognatz, P.E.
75 Laurel Street, Carbondale, PA
Tel. (570)
Case Study #1 – Cameron Compression MSG
These are initial spectrums and waveforms
Just after the startup
© 2008 M&B Engineered Solutions, Inc.
Integrally Geared Air Compressor Case Studies
Vibration Institute Piedmont Chapter Meeting
Augusta, GA 15-Feb-2008
M&B Engineered Solutions, Inc., 2007

14. Case Study #1 – Cameron Compression MSG
Transient Vibration Analysis-
Insights into Machinery Behavior
By Stanley R. Bognatz, P.E.
75 Laurel Street, Carbondale, PA
Tel. (570)
Case Study #1 – Cameron Compression MSG
Primary change is in ‘1X’
This is only 6 days later
© 2008 M&B Engineered Solutions, Inc.
Integrally Geared Air Compressor Case Studies
Vibration Institute Piedmont Chapter Meeting
Augusta, GA 15-Feb-2008
M&B Engineered Solutions, Inc., 2007

15. Case Study #1 – Cameron Compression MSG
Transient Vibration Analysis-
Insights into Machinery Behavior
By Stanley R. Bognatz, P.E.
75 Laurel Street, Carbondale, PA
Tel. (570)
Case Study #1 – Cameron Compression MSG
P-P Displacement in Mils
Frequency in kCPM
NER - #6 JOY
#6 AIRCOMP-P2B PANEL POINT TWO 2ND STAGE BOTTOM 30 60 90
120
Max Amp
.86
Plot
Scale
0.9
11:17:33
13-Sep-07
14:47:17
08-Oct-07
09:20:50
20-Nov-07
08:59:07
10-Dec-07
15:41:50
07-Jan-08
Freq:
Ordr:
Sp 1:
19.05
1.004
.862
Basically the changing amplitude is ‘1X’
What can change in the ‘1X’; the balance condition as the impeller fit slips on the pinion
1X Amplitudes at different samples: 0.793; 0.851; 0.709; 0.713; 0.862
© 2008 M&B Engineered Solutions, Inc.
Integrally Geared Air Compressor Case Studies
Vibration Institute Piedmont Chapter Meeting
Augusta, GA 15-Feb-2008
M&B Engineered Solutions, Inc., 2007

16. Case Study #1 – Cameron Compression MSG
Transient Vibration Analysis-
Insights into Machinery Behavior
By Stanley R. Bognatz, P.E.
75 Laurel Street, Carbondale, PA
Tel. (570)
Case Study #1 – Cameron Compression MSG
Note the lack in change of the multiples during the coast down
© 2008 M&B Engineered Solutions, Inc.
Integrally Geared Air Compressor Case Studies
Vibration Institute Piedmont Chapter Meeting
Augusta, GA 15-Feb-2008
M&B Engineered Solutions, Inc., 2007

17. Case Study #2 – Cameron Compression MSG
Transient Vibration Analysis-
Insights into Machinery Behavior
By Stanley R. Bognatz, P.E.
75 Laurel Street, Carbondale, PA
Tel. (570)
Case Study #2 – Cameron Compression MSG
Lets look at another machine with some different data:
Lets look at some comparisons of data formats and frequency spans
Here is a High and Standard Freq comparison at ‘standard frequencies’
Note the difference in the noise floor of a 10 mV/g vs. 100 mV/g
© 2008 M&B Engineered Solutions, Inc.
Integrally Geared Air Compressor Case Studies
Vibration Institute Piedmont Chapter Meeting
Augusta, GA 15-Feb-2008
M&B Engineered Solutions, Inc., 2007

18. Case Study #2 – Cameron Compression MSG
Transient Vibration Analysis-
Insights into Machinery Behavior
By Stanley R. Bognatz, P.E.
75 Laurel Street, Carbondale, PA
Tel. (570)
Case Study #2 – Cameron Compression MSG
© 2008 M&B Engineered Solutions, Inc.
Integrally Geared Air Compressor Case Studies
Vibration Institute Piedmont Chapter Meeting
Augusta, GA 15-Feb-2008
M&B Engineered Solutions, Inc., 2007

19. Case Study #2 – Cameron Compression MSG
Transient Vibration Analysis-
Insights into Machinery Behavior
By Stanley R. Bognatz, P.E.
75 Laurel Street, Carbondale, PA
Tel. (570)
Case Study #2 – Cameron Compression MSG
Here are the immediate multiples
© 2008 M&B Engineered Solutions, Inc.
Integrally Geared Air Compressor Case Studies
Vibration Institute Piedmont Chapter Meeting
Augusta, GA 15-Feb-2008
M&B Engineered Solutions, Inc., 2007

20. Case Study #2 – Cameron Compression MSG
Transient Vibration Analysis-
Insights into Machinery Behavior
By Stanley R. Bognatz, P.E.
75 Laurel Street, Carbondale, PA
Tel. (570)
Case Study #2 – Cameron Compression MSG
Expanded Frequency Span to 20 kHz
Now we are at 20 kHz Frequency Span
© 2008 M&B Engineered Solutions, Inc.
Integrally Geared Air Compressor Case Studies
Vibration Institute Piedmont Chapter Meeting
Augusta, GA 15-Feb-2008
M&B Engineered Solutions, Inc., 2007

21. Case Study #2 – Cameron Compression MSG
Transient Vibration Analysis-
Insights into Machinery Behavior
By Stanley R. Bognatz, P.E.
75 Laurel Street, Carbondale, PA
Tel. (570)
Case Study #2 – Cameron Compression MSG
Look at how the standard frequency accel drops off
Now we are at 50 kHz
© 2008 M&B Engineered Solutions, Inc.
Integrally Geared Air Compressor Case Studies
Vibration Institute Piedmont Chapter Meeting
Augusta, GA 15-Feb-2008
M&B Engineered Solutions, Inc., 2007

22. Case Study #2 – Cameron Compression MSG
Transient Vibration Analysis-
Insights into Machinery Behavior
By Stanley R. Bognatz, P.E.
75 Laurel Street, Carbondale, PA
Tel. (570)
Case Study #2 – Cameron Compression MSG
From High Freq accel
Are the overall amplitudes really higher than expected?
© 2008 M&B Engineered Solutions, Inc.
Integrally Geared Air Compressor Case Studies
Vibration Institute Piedmont Chapter Meeting
Augusta, GA 15-Feb-2008
M&B Engineered Solutions, Inc., 2007

23. Case Study #2 – Cameron Compression MSG
Transient Vibration Analysis-
Insights into Machinery Behavior
By Stanley R. Bognatz, P.E.
75 Laurel Street, Carbondale, PA
Tel. (570)
Case Study #2 – Cameron Compression MSG
The bottom one is about 1 revolution of the pinion
The middle is about 4 revolutions
This data is showing me the actual amplitudes as opposed to the calculated values in the spectral data
Differing time frames from the high frequency accel
© 2008 M&B Engineered Solutions, Inc.
Integrally Geared Air Compressor Case Studies
Vibration Institute Piedmont Chapter Meeting
Augusta, GA 15-Feb-2008
M&B Engineered Solutions, Inc., 2007

24. Case Study #3 – Cameron Compression MSG
Transient Vibration Analysis-
Insights into Machinery Behavior
By Stanley R. Bognatz, P.E.
75 Laurel Street, Carbondale, PA
Tel. (570)
Case Study #3 – Cameron Compression MSG
Raw
Timebase or
Waveform
High Frequency
Enveloping
A couple of reasons for these two plots
Note that this data was taken using a different PdM system Different amplitude levels from other system
Note that a bull gear ‘fault’ is showing up on the enveloped data, but not on the standard data.
Time frames are different – but 3600 rpm is sec per rev, so there should have been 4 peaks of bull gear rotation
© 2008 M&B Engineered Solutions, Inc.
Integrally Geared Air Compressor Case Studies
Vibration Institute Piedmont Chapter Meeting
Augusta, GA 15-Feb-2008
M&B Engineered Solutions, Inc., 2007

25. Case Study #4 – Ingersoll-Rand Centac II
Note the amplitudes
© 2008 M&B Engineered Solutions, Inc.
Integrally Geared Air Compressor Case Studies
Vibration Institute Piedmont Chapter Meeting
Augusta, GA 15-Feb-2008

26. Case Study #4 – Ingersoll-Rand Centac II
Transient Vibration Analysis-
Insights into Machinery Behavior
By Stanley R. Bognatz, P.E.
75 Laurel Street, Carbondale, PA
Tel. (570)
Case Study #4 – Ingersoll-Rand Centac II
2X of gear mesh is higher than 1X;
Sidebands are bullgear speed
© 2008 M&B Engineered Solutions, Inc.
Integrally Geared Air Compressor Case Studies
Vibration Institute Piedmont Chapter Meeting
Augusta, GA 15-Feb-2008
M&B Engineered Solutions, Inc., 2007

27. Case Study #4 – Ingersoll-Rand Centac II
Transient Vibration Analysis-
Insights into Machinery Behavior
By Stanley R. Bognatz, P.E.
75 Laurel Street, Carbondale, PA
Tel. (570)
Case Study #4 – Ingersoll-Rand Centac II
Vane pass multiples are highest amplitudes
© 2008 M&B Engineered Solutions, Inc.
Integrally Geared Air Compressor Case Studies
Vibration Institute Piedmont Chapter Meeting
Augusta, GA 15-Feb-2008
M&B Engineered Solutions, Inc., 2007

28. Thank You – Any Questions?
© 2008 M&B Engineered Solutions, Inc.
Integrally Geared Air Compressor Case Studies
Vibration Institute Piedmont Chapter Meeting
Augusta, GA 15-Feb-2008