Page 311 - Root Cause Failure Analysis

Glossary 299
operating dynamics Deals with the motion of a system under the
influence of forces, especially those that originate
outside the system under consideration.
operating envelope The physical requirements and dimensions of a
specific application.
orifice An aperture or hole.

oscillator An electronic circuit that converts energy from a
direct-current source to a periodically varying
electric output.
parameter A quantity that is constant under a given set of
conditions but may be different under other
conditions.
peripheral Pertaining to or located at or near the surface of
a part.
pinion The smaller of a pair of gear wheels or the
smallest wheel of a gear train.

piston A sliding metal cylinder that reciprocates in a
tubular housing, either moving against or moved
by fluid pressure.
pitch Distance between similar, equally spaced gear
tooth surfaces along a given line or curve.

pitch, diametrical A gear tooth design factor that is a measure of
tooth size in the English system; expressed as
the ratio of the number of teeth to the diameter
of the pitch circle measured in inches.
pneumatic Pertaining to or operated by air or other gas.

positive displacement compressor A device that confines successive volumes of
fluid within a closed space in which the pressure
of the fluid is increased as the volume of the
closed space is decreased.
positive displacement pump A device in which a measured quantity of liquid
is entrapped in a space, its pressure is raised, and
then it is delivered.

predictive maintenance The practice of using actual operating conditions
of plant equipment and systems to optimize total
plant operation. It relies on direct equipment
monitoring to determine the actual mean-time-to-
failure or loss of efficiency for each machine train
and system in a plant. This technique is used in
place of traditional run-to-failure programs.