Vibration and Oil analysis

Question 1

What cpm is displacement used?

Answer 1

Below 600 cpm or 1000 rpm

Question 2

What cpm is velocity used?

Answer 2

600-60,000 cpm

Question 3

What cpm is acceleration used?

Answer 3

Anything above 60,000 cpm

Question 4

What is phase?

Answer 4

The time relationship between 2 related events

Question 5

What is synchronous vibration?

Answer 5

A frequency that is a whole multiple of the rotating speed

Ex.

1 x RPM

2 x RPM

Question 6

What is non-synchronous vibration?

Answer 6

Frequencies that are not whole multiples of the rotating speed of the machine

Question 7

What are sub-synchronous vibrations?

Answer 7

Frequencies that occur at less then the rotating speed of the machine

Question 8

What is natural frequency?

Answer 8

The frequency in which an object or system naturally vibrates when a forcing function has been introduced

Question 9

At what percent should you keep a machine out of its resonant frequency?

Answer 9

20%

Question 10

What is frequency?

Answer 10

How often an event happens in a unit of time or in one cycle

Ex.

Cycles per second (cps , Hz)

Cycles per minute (cpm)

Orders

1 cps = 1 Hz = 60 cpm

Question 11

What is amplitude?

Answer 11

Indicates how much a machine is vibrating.

The distance from the at rest position and indicates the magnitude of a measure signal

Question 12

What is displacement?

Answer 12

The motion from one extreme of the motion to the other (peak to peak)

Question 13

What are the 4 ways to mount transducers from best to okay?

Answer 13

Stud- Best

Magnet- Good

Probe- Fair

Or
Adhesive bond to a flat surface

Question 14

What are the 3 mounting positions of a transducer?

Answer 14

Horizontal, vertical, axial

The transducer is only capable of picking up a vibration that is in line with the transducer

Question 15

What are the characteristics of imbalance?

Answer 15

Identified by a frequency that is 1 x rpm

Amplitude of the vibration increases with the shaft speed

If the problem is imbalance, the phase is stable

Question 16

Characteristics of shaft misalignment on a vibration signature?

Answer 16

Frequency is usually 1 x rpm but severe misalignment can be 2 or 3 x rpm

Axial vibration component is usually about 1/2 or more of the radial amplitude

Phase readings can be erratic

Question 17

Vibration characteristics of gear problems?

Answer 17

Usually several times higher then
1 x rpm unless only one tooth is bad

Is a multiple of the number of teeth times the rpm of the shaft

Question 18

Inner race bearing frequency?

Answer 18

Frequency= 0.60 x (number of rollers) x rpm

Question 19

Outer racing bearing frequency?

Answer 19

Frequency= 0.40 x (number of rollers) x rpm

Question 20

Oil whirl vibration characteristics?

Answer 20

Usually occurs at 45% to 50% of the shaft rotation

Question 21

Mechanical looseness vibration characteristics?

Answer 21

Dominant vibration frequency of
2 x rpm

Vibrations at other frequencies such as 1/2 and
4 x rpm

Question 22

Belt drive problem vibration frequencies?

Answer 22

Are a multiple of the machine speed, which are 1, 2, 3 or 4 times rpm of the belts

Question 23

What are the 4 products of oil oxidation?

Answer 23

Gum
Varnish
Sludge
Acids

Question 24

What are the particle counts in the ISO cleanliness standard?

Answer 24

4 microns

6 microns

14 microns

Question 25

When talking about thermal imaging, what is emissivity?

Answer 25

The materials ability to emit thermal radiation

Question 26

Where should you not have oil sample collection points in a system?

Answer 26

At dead pipe legs, after filters or separators

Question 27

A thermal imaging camera produces an image called?

Answer 27

A thermogram

Question 28

What does critical speed refer too?

Answer 28

The speed at witch a rotor will near its natural frequency.

It create a large increase in vibration and can damage the machine.

You should keep the machine 20% - 30% outside of a rotors critical speed

Question 29

What type of transducer does not generate its own power?

Answer 29

Displacement transducers

Question 30

What type of transducers generate there own power?

Answer 30

Velocity transducers

Acceleration transducers