Yokogawa digitalYEWFLO (DY) - Manual (Page 111)

IM 1F2B4-01-YIA
Page 106
GLOSSARY OF TERMS
Strouhal number - A dimensionless number that when constant defines the region of linear flow
measurement. This value is defined by geometric dimensions..
Style ‘E’ YEWFLO - The current design of the YEWFLO. An intelligent vortex flowmeter, utilizing
microprocessor electronics, custom Application Specific Integrated Circuits (ASIC) and surface
mount assembly technology.
TBL - An optional local digital indicator used with the YEWFLO to indicate the rate of flow or total
flow. It is also capable of doing some of the configuration of the YEWFLO electronics to match the
meter to the application.
Terminal box - A small housing mounted on top of the vortex meter body. It is only required when the
electronics converter is mounted remotely. Its purpose is to provide a junction box for the wires
coming from the vortex sensor and the cables to the remote converter.
TLA (trigger level adjustment) - An adjustment or setting in the YEWFLO electronics which
determines the minimum amplitude of vortex signal to be detected by the sensor. Signal amplitudes
below the TLA setting will be ignored.
TP2 (test point 2) - Located on the YEWFLO amplifier circuit board, this is the amplified signal from
the shedder bar. The wave form is typically sinusoidal in shape. At high flow rates the wave form
tends to flatten on the top and bottom.
TP2(Vp-p) - Displays the peak to peak amplitude of the signal output from the sensor as found on test
point TP2.
Velocity - The speed at which a fluid travels within a pipe. Usually expressed in meters per second.
Viscosity - The internal resistance to flow within a fluid. The shear of the liquid or gas tending to
prevent the flow of the fluid. In the case of a liquid, the viscosity decreases as the temperature
increases. In a gas, the viscosity increases as the temperature increases.
Volumetric flow - Fluid flow that is metered in volumetric units such as gallons or cubic feet without
regard to the weight or mass per unit volume.
Von Karman vortex street - The pattern of vortex swirls being shed from the bluff body. Named after
T. Von Karman who did considerable research on the vortex shedding phenomenon in the early days of
the 20th century.
Wafer body style - YEWFLO meter body held in the pipeline by clamping between the mating flanges
using long bolts and nuts. The meter body itself does not have flanges, but relies on the clamping
pressure to seal against leakage.