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Chapter 1. Features and Capabilities
2 Transport® Model PT878 Portable Liquid Flowmeter User’s Manual
1.1 Overview (cont.)
To assist you, the PT878 is fully equipped with context-sensitive on-line
help which is accessible at any time by simply pressing the “?” (Help) key.
Internal diagnostic and troubleshooting features help isolate and remedy
common flowcell and transducer problems.
The PT878 operates with all standard GE transducers - wetted, clamp-on,
hybrids (Pan-Adapta
®
plug), and buffered styles.
A built-in ultrasonic thickness gauge capability measures the pipe wall
thickness when used with the optional thickness transducer.
1.2 System Description
The PT878 is one part of the flowmeter system. The flowmeter system
consists of two essential subsystems: the flowcell and the electronics
package (the PT878).
1.2.1 The Flowcell
The flowcell is that part of the system that uses ultrasonic pulses to
interrogate the flow. It consists of the flowcell pipe and the transducers.
A. FLOWCELL PIPE - The flowcell can either be created in the existing
piping (for example, by inserting wetted transducers into the pipe, or
clamping non-wetted transducers onto the pipe), or inserted as a
substitute pipe section (spoolpiece). The flowcell must provide
mechanical support for the transducers and assure stable fluid conditions
for accurate flow measurement.
B. TRANSDUCERS - The transducers 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. In other words,
they act like loudspeakers when transmitting the signal and microphones
when receiving it. In the PT878 system, each transducer acts as both a
receiver and transmitter, since a series of ultrasonic pulses are alternately
sent upstream and then downstream through the flowcell.