the Balmac 211 Vibration Meter User

BALMAC
VIBRATION
METER USER
MANUAL
BASIC
UNDERSTANDING OF
MACHINERY
VIBRATION
Revised as of 2015
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MODEL 211
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Balmac Model 211
Vibration &
Electronic
Stethoscope
Meter Kit
MODEL 211
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MODEL 211
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MODEL 211
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MODEL 211
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MODEL 211
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MODEL 211
AMPLITUDE
Unsteady
Rotates at Beat Frequency
Radial
Proportional to Looseness
Erratic
Usually Low
Radial Unsteady
Erratic
Variable at Beat Rate
1 or 2 x RPM
High No. Gear Teeth x RPM
2 x RPM
Sometimes
1 x RPM
1 or 2 x Belt Speed
1 or 2 x Line Frequency
(3600 or 7200 CPM for
60Hz Power) May appear at
1 x RPM
45 - 55% RPM
No. Blades or Vanes x RPM
Near 1 x RPM
Specific Criticals
Bent Shaft
Defective Gears
Mechanical Looseness
Defective Drive Belts
Electrical
Oil Whip
Hydraulic-Aerodynamic
Beat Frequency
Resonance
Single Reference Mark
Unstable
1 or 2 Marks Sometimes
Slipping
Use Strobe to Freeze Belt
in OSC Mode
1 or 2
Unsteady
1 or 2
Pulley Diameter x 3.141
Belt Length
x Pulley RPM
Phase will shift 180° going through resonance (90° at resonance). Amplitude will peak at
resonance. Resonance in frame can be removed by changing rotor operating speed or by
changing the stiffness of the structure.
Caused by two machines, mounted on same base, running at close to same RPM.
May excite resonance problems.
Caused by excessive clearance in sleeve bearings or by underloaded bearings. Will change
with viscosity of oil (temperature).
Looks like mechanical unbalance until power is removed. Then drops dramatically.
Look for cracks, hard spots, soft spots or lumps. Loose belt. Changes with belt tension.
Belt RPM =
Calculate the belt RPM using:
Check movement of mounting bolts in relation to the machine base. Difference between base
and machine indicates amount of looseness.
Use velocity measurement. Often affected by misalignment. Generally accompanied by side
band frequency. Pitting, scuffing and fractures are often caused by torsional vibrations.
Frequency sometimes as high as 1 million CPM or more.
Similar to misalignment. Use phase analysis.
May appear to be unbalanced. Shaft and bearing amplitude should be taken. If shaft
vibration is larger than the bearing, vibration amplitude indicates clearance.
Use phase analysis to determine relative movement of machine or bearings. Use a dial
indicator if possible. Often diagnosed as a bent shaft.
Can be caused by misalignment of V belts.
Velocity readings are highest at defective bearing.
As failure approaches, the amplitude of the velocity signal will increase and its frequency will
decrease. Cage frequency is approximately 0.6 x RPM x number elements.
A common cause of vibration.
COMMENTS
3) LEARN ABOUT ELECTRICALLY INDUCED BEARING DAMAGE & SHAFT CURRENTS
2) LEARN ABOUT VIBRATION VOLUME 2: ADVANCED VIBRATION ANALYSIS
1) LEARN ABOUT VIBRATION VOLUME 1: BASIC UNDERSTANDING OF MACHINERY VIBRATION
NOTE: There are several additional detailed articles that identify more complicated vibration sources at the Vibes Corp website titled:
High
High Axial
Single Reference Mark
Not Large
Use Displacement Mode Up
to 6000 CPM
1 x RPM
Sleeve Bearing
Often 2, Sometimes 1 or 3
High Axial
Axial 50% or more of
Radial
1, 2 or 3 x RPM
Misalignment of Coupling or
Bearing
Unstable
Use Velocity
Very High-Often From 10 to
100 x RPM
Single Mark (Steady)
PHASE
Defective Anti-Friction
Bearings
Highest in Radial DirectionProportional to Unbalance
1 x RPM
FREQUENCY
Unbalance
CAUSE
Common Vibration Sources Identification Guide
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MODEL 211
BALMAC 242 Pocket Vibration Meter
Displacement, Velocity, Acceleration.
Pocket size with battery and carrying case Large LCD display and Pushbutton Operation.
Mils (pk-pk), in/sec, g’s pk. 3 selectable ranges (200-20-2)180 to 60,000 RPM
(The 242 meter is not available in Metric at this time)
200 Digital Vibration Meter
Displacement,Velocity, Acceleration General Headphones/Electronic Stethoscope
Portable with Battery and Carrying Case Pushbutton Operation.
Mils (pk-pk), In/sec (pk), g’s (pk) (4) Selectable ranges (200, 20, 2, VLR) 180 to
120,000 RPM Metric Version is Model 200M
205 Digital Vibration Meter
Displacement Velocity, Acceleration Small 100 mV/g Accelerometer Optional Headphones/Electronic Stethoscope Portable with Battery and Carrying Case Large LCD
Display Pushbutton Operation
Mils (pk-pk), In/sec (pk), g’s (pk) (4) Selectable Ranges (200, 20, 2, VLR) 26 to 300,000
RPM Metric version is Model 205M
211 Vibration Meter
Displacement, Velocity, Acceleration General Purpose Meter Optional Headphones/
Electronic Stethoscope Portable with Battery and Carrying Case
mils (pk-pk), In/sec (pk), g’s (pk) 120 to 150,000 RPM Metric Version is Model 211M
ranges: - .03 - 1 - 3 - 10 - 30 - 100
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MODEL 211