VA Flashcards
(12 cards)
What causes vibration?
Misalignment, looseness, imbalance
Vibration levels will increase due to?
A. An increase in machine clearances, wear
B. Machinery defects, bearings
C. Deterioration of overall condition,
Why carry out VA on equipment?
A. To monitor a machines condition
B. To anticipate machinery failure
C. TO assess and control the amount of noise and vibration passed to the ships hull
D. As a quality control function
E. To detect and identify faults in a machine
What is peak velocity?
The maximum speed of a vibrating component which occurs as it passes through the rest position. (Units mm/sec)
What is ESP?
Envelope signal processing, the term used for the condition of rolling element bearings.
What is peak acceleration?
The maximum rate of the change of velocity which occurs at the limits of travel. (Units, g or can be written as mm/sec.
Where do you take a reading on a machine?
Vibration readings are taken at all bearing positions there are 2 reasons for this:
- This is where the vibration readings will be concentrated.it is where the stationary and rotating parts of the machine come together.
- they are the most accessible parts of the machine.
How do you identify the bearing positions?
The bearing positions are identified either alphabetically or numerically. Starting with the non-drive end bearing or the prime mover, the bearing position will be either A or 1 following the direction of drive, the next bearing position will be position B or 2 etc.
What readings are taken and how many?
Three velocity readings are taken at each bearing position, in either the horizontal, vertical or axial planes. This is because vibration amplitudes will vary in each plane with different machinery problems.
Two ESP readings are taken at each position where there is a rolling element bearing. These readings are taken in either the horizontal or vertical directions only.
Finally, velocity readings are taken in the vertical direction above and below the four corner mounts.
How are mount positions identified?
Diagram
What does 3PDX stand for?
Position 3, pump, drive end, axial
What does the code 2MTB stand for?
Position 2, mount, bottom
