Vibration Module Questions A+B and Balancing Flashcards
Vibration analysis refers to;
Detecting, measuring, and analyzing the vibration, determining whether it is within normal machine parameters.
Oil condition monitoring allows the technician to;
Analyze contamination in the lubricant.
Infrared Thermography allows for the measurement of;
Heat being emitted.
True or False;
Frequency can be measured in cpm.
True
True or False;
Hertz is a measurement of frequency.
True
Amplitude is;
a- how often
b- dominant frequency
c- imbalance
d- how much
D - How much
Which reading is used to see how one part is shaking in relation to another part?
Phase
What is necessary to cause vibration in a machine or piece of equipment?
Force
What is peculiar to imbalance amplitude readings?
Similar in the vertical and horizontal directions.
A type of resonance that occurs when a shaft or other rotating component is revolving at a speed which has reached or is close to reaching its natural frequency is known as;
Critical Speed
What term identifies the frequency with the largest amount of vibration?
Dominant Frequency
What is the purpose of a transducer?
To convert a vibration into an electrical signal.
Name 3 types of transducers;
- Displacement
- Velocity
- Accelerometer
Describe HVA measurements;
H - Horizontal Position
V - Vertical Position
A - Axial Position
Why is it a good idea to take readings when the machine is installed?
Because the initial signatures establish a baseline reference and give you a guide to trends with the machine.
Why can you not ignore the small vibrations showing up at each side of the dominant frequency on a graph?
They could be indications of impending bearing troubles.
What are the 4 products of oxidation in oil?
- Gum
- Varnish
- Sludge
- Acids
When an oil sample is removed from a point in a circulating system, it is called a ____ ____ sample.
LIVE ZONE
Do not have oil sample collection points located at _____________ or _____________.
Dead pipe legs or after filters or separators.
True or False;
The oil sample bottle is always filled completely full.
False
- You must allow room in the container for agitating the sample at the analysis lab.
True or False;
Infrared radiation is visible.
False
- Infrared radiation is visible, but it gives off heat.
A thermal imaging camera produces an image called a;
THERMOGRAM
Mechanical equipment tends to ____________________ prior to failure.
RISE IN TEMPERATURE
Emissivity is the materials ability to;
EMIT THERMAL RADIATION
Define imbalance;
Imbalance is the unequal distribution of weight about a centreline.
List 4 ways a machine becomes unbalanced;
- Wear
- Buildup
- Cracks
- Fatigue
How does imbalance affect vibration?
The greater the amount of imbalance present, the greater the amount of vibration felt.
If an imbalance condition is present within a machine, how are the forces from imbalance affected by rotor speed?
The amount of force caused by the lack of balance is proportional to the rpm squared.
How does doubling the rotor speed affect the force caused by imbalance?
Doubling the rpm quadruples the force caused by imbalance.
When the source of vibration is primarily imbalance, how do the vertical and horizontal phase readings compare?
The vertical and horizontal readings are similar.
Why are horizontal and vertical phase readings not exactly equal?
Because the pickup axis is oriented in a different angular position.
Imbalance appears at what frequency of vibration?
1x rpm
What are 3 other sources of 1x rpm vibration?
- Bent Shaft
- Eccentric armature
- Misaligned shafts
- Imbalance
True or False;
To balance, you should be able to observe a reference mark on the shaft.
True
- When balancing you should have a reference mark on the shaft.
True or False;
Couple imbalance is created by equal heavy spots at each end of the rotor, but on opposite sides of the centreline.
True
-Couple imbalance is caused when heavy spots are on opposite sides of the centreline.
True or False;
With couple imbalance, there is a 180 degree phase difference between rotor ends.
True
- With a couple imbalance there is a 180 degree phase difference between rotor ends.
True or False;
When balancing, the reference mark does not change when the trial weight location is changed.
False;
- The reference mark changes if the heavy weight changes.
