Galvanic Applied Sciences Monitek AT3, Operating & Installation Manual

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MODEL AT3 5 – 1
SECTION V APPENDIX
GLOSSARY OF TERMS
Chamber : The short piece of piping in which the AT3 transducer is positioned (see sensor).
Detection threshold
: The level that the signal from an acoustic reflection must exceed before it Is
counted by the receiver. A number from 1 to 255, it is usually shortened to DT.
Far wall pulse : Acoustic reflections from the inside diameter of the pipe opposite the transducer. There
will usually be two or three such pulses.
Focal region
: The area about the focal point where particle measurements are made.
Lens : The material (usually plastic) onto which the transducer crystal is bonded. The lens focuses
acoustic energy to increase system sensitivity, just as a magnifying glass focuses light energy.
The lens is that part of the transducer that comes into contact with the process fluid.
Main bang
: The signal returned from sound resonating in the transducer.
Main bang duration : A characteristic of the transducer related to the length of
time
it reverberates as a
result of the main bang. The transducer must "ringdown" quickly to allow detection of the return
echoes.
Piezoelectric : The property possessed by some substances to deform when a voltage is applied across
them. Many common substances, like quartz, are piezoelectric.
Piezoelectric crystal : The small disk of material in the transducer that converts the electrical energy
from the pulser into acoustic (sound) energy. Crystals in the AT3 transducers are generally made
of lithium niobate (LiNb03).
Preamplifier : The circuit that amplifies the signals from particle echoes before they are transmitted to the
receiver. This minimizes interference from cable noise.
Pulse-echo
: A configuration in which the same transducer transmits pulses and receives acoustic
reflections. The AT3 operates in the pulse-echo configuration.
Pulser : The circuitry that creates the electrical pulses sent to the transducer. The pulser transmits pulses
at either 5 or 15 MHz
RF
: Short for radio frequency, which is any frequency in the range that radio waves may be
transmitted (10KHz to 300 GHz).
Receiver : The receiver circuitry processes the signals from acoustic reflections from contaminants in the
monitored liquid.
Receiver window : The time gate used to define the region in the monitored liquid in which acoustic
reflections must occur in order to be counted. This prevents echoes from anywhere outside the
focal region from being counted. The window width is factory set to 5µs and is adjustable.
Resonant frequency : The "natural" frequency of oscillation of a circuit or crystal, or that frequency at
which the most power is produced or transmitted. Crystals used in the AT3 transducers have
resonant frequencies of either 5 or 15 MHz.
Sensor assembly : The unit comprised of a transducer and preamplifier.
Transducer : A device that converts one form of energy to another. Specifically. the AT3 transducers
convert electrical pulses to acoustic pulses and acoustic energy back to electrical energy.