Page 179 - An Introduction To Predictive Maintenance

Vibration Monitoring and Analysis 169

and systems in a typical plant. Techniques
include vibration analysis, ultrasonics, ther-
mography, tribology, process monitoring,
visual inspection, and other nondestructive
analysis methods.

Maximum frequency Broadband analysis techniques, which are
used to monitor the overall mechanical con-
dition of machinery, are based on the overall
vibration or energy from a frequency range
of zero to the user-selected maximum fre-
quency (F MAX).
Mil One one-thousandth of an inch (0.001 inch).

Moment of inertia The sum of the products formed by multi-
plying the mass of each element of a body
by the square of its distance from a
specified line. Also known as rotational
inertia.
Oscillate To move back and forth with a steady, unin-
terrupted rhythm.

Periodic motion A motion that repeats after a certain interval.
Phase angle The difference between the phase of a sinu-
soidally varying quantity and the phase of a
second quantity that varies sinusoidally at the
same frequency. Also known as phase differ-
ence.
Piezoelectric Describes a crystal or film that can generate
a voltage when mechanical force is applied
or produce a mechanical force when a
voltage is applied.
Predictive maintenance The practice of using actual operating condi-
tions of plant equipment and systems to opti-
mize total plant operation. Relies on direct
equipment monitoring to determine the
actual mean-time-to-failure or loss of effi-
ciency for each machine-train and system in
a plant. This technique is used in place of tra-
ditional run-to-failure programs.

Profile Refers to either time-domain (also may be
called time trace or waveform) or frequency-
domain vibration curves.
Quadratic Any second-degree expression.