2
T E C H N O L O G Y
Model 344 and 345 systems consists of three main com-
ponents: an ultrasonic transducer, a transmitter, and an
interconnecting cable package.
The transducer contains a piezoelectric crystal that con-
verts electrical signals generated by the transmitter into
ultrasonic pulses. These pulses, or sound waves, are
directed through the air toward the liquid surface. They
are then reflected off the liquid surface as an echo, and
returned to the transducer. The piezoelectric crystal then
converts the returned echo into an electrical signal which
is analyzed by the transmitter. The elapsed time between
the generation of the ultrasonic pulse and the return echo
is proportional to the distance between the face of the
transducer and the liquid surface. The distance value is
used by the transmitter to compute level, volume, or flow
in the engineering units selected by the user.
T Y P I C A L M O U N T I N G C O N F I G U R A T I O N S
In Figure 1, the transducer is installed above the liquid
surface, and the transmitter is mounted as far as 500 feet
(152 meters) away. A minimum dead band distance must
be allowed between the face of the transducer and the
maximum level attainable. This dead band distance is
18 inches (460 mm) for the Model 384 transducer, and
12 inches (305 mm) for the Model 385 transducer.
Figure 1
Typical Transducer Mounting – Level/Volume
Transducer
Air
Liquid
Dead Band
Minimum Model 344: 18 inches (460 mm)
Model 345: 12 inches (305 mm)
Model 345
25 feet (7.6 m)
maximum
Model 344
35 feet (10.7 m)
maximum
Range
Span
Maximum Model 345: 24 feet (7.3 m)
Model 344: 33.5 feet (10.2 m)
E C H O M A S T E R T R A N S D U C E R
EchoMaster transducers are available in a wide variety of
configurations to accommodate a broad range of industri-
al and municipal applications. The 344 uses the powerful
38 kHz Model 384 Kynar transducer, and is primarily used
for level and volume applications. The 345 uses the
50 kHz Model 385 transducer that is available in either
Kynar or 316 stainless steel. The higher frequency 50 kHz
transducer makes the 345 well suited for open channel
flow, and shorter range applications.
Operating
Material
Insertion
NPT Process
Housing
Frequency
Lengths
Connection
Model 384
38 kHz
Kynar
3" & 10"
1" or 2"
none, aluminum, or
Model 385
50 kHz
Kynar or 316 SS
3", 6", & 10"
3
⁄
4
" or 2"
316 stainless steel
