Monitoring and Analysis Flashcards
True or false: Excessive vibration is a symptom of a machine that can lead to machine damage or failure.
True
All machines have some vibration during operation.
What is vibration analysis?
Measuring and determining if vibrations are within normal parameters.
True or false: Vibration monitoring can be both periodic sampling or constant monitoring.
True
This depends on the type of machinery in use.
What is the main limitation of a preventative maintenance program (changing oil at scheduled internals) vs. an oil condition monitoring program?
The levels of oil contamination.
Preventative maintenance oil programs are based off of the expected lifespan of the oil and additives off of running conditions, and are unable to detect excessive contamination.
True or false: Over time, lubricating oils lose their ability to separate metal surfaces.
True
As it pertains to maintenance, what is infrared thermography (IRT)?
A temeprature analysis programs.
True or false: An infrared thermometer is a contact radiant energy detector.
False
It is a noncontact radiant energy detector.
____ is the movement of a body about its reference position.
Vibration
For rotating equipment, what is the reference point used for vibration analyisis?
The shaft centreline.
This test is the only way to find the direct cause of vibration on a machine.
A vibration signature analysis.
A signature is a graphical depiction of vibration frequency.
As it pertains to vibration analysis, what is a signature?
A graphical representation of vibration frequency.
True or false: With a proper vibration analysis, all vibration in a machine can be eliminated.
False
There will always be some vibration in a machine.
All objects vibrate in response to a:
Forcing function
The forcing functions and their signatures indicate the cause of vibration.
As it pertains to vibration, what is a forcing function?
An input or influence that causes a system to vibrate.
These can be internal (unbalanced rotor) or external (wind).
In machinery, vibration is the accumulation of what three things?
- the application
- wear of the machinery
- machine design
What two physical properties of a machine have a direct effect on the vibratory signature of the machine?
- stiffness
- mass
Changing either of these will result in a change in the vibratory signature.
In vibration analysis, what are sine waves?
Graphical depictions of a vibration cycle.
True or false: With vibration, one cycle per minute (cpm) = 1 hertz (Hz).
False
1 cycle per second (cps) = 1 hertz (Hz)
How many hertz (Hz) does a vibration signature of 60 cpm equal?
60 cpm = 1 Hz
Hertz is how many cycles per second → 1 cps = 1 Hz = 60 cpm.
True or false: With vibration, 1 cps = 1 Hz.
True
1 cps = 1 Hz = 60 cpm
With vibration, ____ is how often an event happens in a unit of time or in one cycle.
frequency
What are three ways that the frequency of a vibration can be expressed?
- cycles per second (cps)
- cycles per minute (cpm)
- orders*
*Orders are multiples of the operating speed of the machine ⟶ 1x is the same as the rpm, 2x is twice the rpm, etc.
When completing vibration analysis on rotating machinery, vibration cycles (frequency) are referenced to what?
The rpm of the machine.
This is the fundamental frequency → Do not confuse cpm with rpm.
When it comes to vibration analysis, what are orders?
Multiples of the operating speed of the machine.
2x order → 2x machine rpm = twice per revolution.