Filter
Top Products
Appendix G. Glossary
262 Transport® Model PT878 Portable Liquid Flowmeter User’s Manual
Transit-Time — Flow measurement technique based on the principle that
when ultrasonic pulses are transmitted through a moving liquid, the pulses
that travel in the same direction as the fluid flow (downstream) travel
slightly faster than the pulses that travel against the flow (upstream). When
the liquid in the pipe is not flowing, the transit-time downstream equals the
transit-time upstream. When the liquid is flowing, the transit-time
downstream is less than the transit-time upstream. The difference between
the downstream and upstream transit-times is proportional to the velocity of
the flowing liquid, and its sign indicates the direction of flow.
Traverses — Number of times the ultrasonic signal crosses the pipe.
User Functions — User-defined mathematical equations for use with any
measurement.
User Tables — User-defined tables of data for use with user functions.
Velocity Averaging — Parameter that averages a desired number of
velocity measurements to smooth out or dampen noise in the system.
Watchdog Test — Option in the Service Menu that tests the watchdog
timer circuit. If a software error causes the meter to stop responding, this
circuit automatically resets the meter
Wave Snapshot — Option in the Service Menu that enables users to
capture waveforms for downloading to a PC for analysis, or for simulating a
flow measurement.
Wedge Angle — Angle of the transducer’s ultrasonic transmission in the
transducer wedge.
Zero Cutoff — Parameter that causes velocity measurements less than the
absolute value of the cutoff (either positive or negative values) to be
reported as zero.