GE PT878 User Manual
Appendix G. Glossary
Transport® Model PT878 Portable Liquid Flowmeter User’s Manual
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Soundspeed — Speed at which a sound wave travels through a given
material.
material.
Thickness Gauge — Option that allows the PT878, with an optional
thickness gauge transducer, to determine the thickness of most standard
metal and plastic pipe materials over a range from 0.05 to 3 in. (1.3 to 76.2
mm).
thickness gauge transducer, to determine the thickness of most standard
metal and plastic pipe materials over a range from 0.05 to 3 in. (1.3 to 76.2
mm).
Tw (time in wedge) — Time the transducer signal spends travelling
through the transducer and cable. This time has to be subtracted from the
transit time to determine how much time the signal spent in the fluid.
through the transducer and cable. This time has to be subtracted from the
transit time to determine how much time the signal spent in the fluid.
Tracking Windows — A feature which allows the receive window to move
automatically if the ultrasonic signal is lost. The PT878 will set up the
window in various positions based on a minimum and maximum
soundspeed range. In seek mode, the meter will test every position until it
detects a receive signal that passes the error tests. The first window (highest
soundspeed setting) that passes the tests is the detected window. The meter
will then track the receive signal.
automatically if the ultrasonic signal is lost. The PT878 will set up the
window in various positions based on a minimum and maximum
soundspeed range. In seek mode, the meter will test every position until it
detects a receive signal that passes the error tests. The first window (highest
soundspeed setting) that passes the tests is the detected window. The meter
will then track the receive signal.
Transducer Delay — Time the ultrasonic signal takes to travel from the
meter to the pipe material surface. It is a similar measurement to Tw, except
that the delay is subtracted from the transit time to find out how much time
is spent in the wall.
meter to the pipe material surface. It is a similar measurement to Tw, except
that the delay is subtracted from the transit time to find out how much time
is spent in the wall.
Transducers — Devices that convert electrical energy into ultrasonic
pulses when in a transmit cycle, and convert the ultrasonic pulses back to
electrical energy when in a receive cycle. They can be fixed to the outside
of the flowcell pipe (clamp-on) or inserted into the pipe to directly measure
the fluid (wetted).
pulses when in a transmit cycle, and convert the ultrasonic pulses back to
electrical energy when in a receive cycle. They can be fixed to the outside
of the flowcell pipe (clamp-on) or inserted into the pipe to directly measure
the fluid (wetted).
Transmitter Sample Size —Number of pulses the transmitter emits in one
direction (upstream or downstream) before transmitting in the other
direction. It is set to 8 by default.
direction (upstream or downstream) before transmitting in the other
direction. It is set to 8 by default.