GE PanaFlow MV80, Руководство пользователя

Страница: 157 / 164

PanaFlow™ MV80 & MV82 User’s Manual 145
Appendix D. Glossary
psig
Pounds per square inch gauge
P
V
Liquid vapor pressure at flowing conditions (psia or bar absolute)
Q
Flow rate, usually volumetric
Rangeability
Highest measurable flow rate divided by the lowest measurable flow rate
Reynolds Number
or Re
A dimensionless number equal to the density of a fluid times the velocity of the fluid times the
diameter of the fluid channel, divided by the fluid viscosity (i.e., Re = VD/
ρ
). The Reynolds
number is an important number for vortex flowmeters because it is used to determine the
minimum measurable flow rate. It is the ratio of the inertial forces to the viscous forces in a
flowing fluid.
RTD Resistance temperature detector, a sensor whose resistance increases as the temperature rises
scfm
Standard cubic feet per minute (flow rate converted to standard conditions,
as shipped 14.696 psia and 59° F). User definable.
Shedder Bar
A non-streamlined body placed into a flow stream to create vortices. Also called a Bluff Body.
Strouhal Number
or St
A dimensionless number equal to the frequency of vortices created by a bluff body times the
width of the bluff body divided by the velocity of the flowing fluid (i.e., St = fd/V). This is an
important number for vortex flowmeters because it relates the vortex frequency to the fluid
velocity.
Totalizer An electronic counter which records the total accumulated flow over a certain range of time
Traverse
The act of moving a measuring point across the width of a flow channel
Uncertainty The closeness of agreement between the result of a measurement and
the true value of the measurement
V
Velocity or voltage
VAC Volts, alternating current
VDC
Volts, direct current
VORTEX An eddy of fluid