Page 316 - Root Cause Failure Analysis

304 Root Cause Failure Analysis
velocity head The square of the speed of flow of a tluid
divided by twice the acceleration of gravity. It is
equal to the static pressure head corresponding
to a pressure equal to the kinetic energy of the
fluid per unit volume.
vibration analysis Predictive-maintenance technique that monitors
the noise or vibrations generated by plant
machinery or systems to determine their actual
operating condition. The normal monitoring
range for vibration analysis is from less than 1 to
20,000 Hz.
vibration profile Refers to either time-domain (also called time
truce or wuvefunn) or frequency-domain
vibration curves.

vibration signature Frequency-domain vibration curve, which is
amplitude (displacement, velocity, or acceleration)
versus frequency. Frequency-domain data are
obtained by converting time-domain data using a
mathematical technique referred to as fast Foiirier
transform. Time-domain data are plotted as
amplitude versus time.

viscosity The resistance that a gaseous or liquid system
offers to flow when subjected to a shear stress;
also known asfiow resistance or internalffiction.
viscous fluid A fluid whose viscosity is sufficiently large to
make the viscous forces a significant part of the
total force field in the fluid.
volute Spiral part of a pump casing that accepts the
fluid from the impeller and carries it to the
outlet.
vortex Flow exhibiting rotary motion as in an eddy or
whulpool.