more dense, resulting in slower sound velocity. Since
measurement is directly dependent on sound speed, it is
necessary to compensate for temperature changes. All
Magnetrol’s transducers include a temperature compensa-
tion circuit which continuously monitors the temperature
at the sensor and compensates for variations over the full
temperature range of the transducer.
Ultrasonic non-contact devices are typically rated for
a maximum range in ideal conditions. But process condi-
tions can impact the maximum range of measurement.
These conditions include surface agitation, vapors and
steam, foam and air movement. A derating multiplier can
be computed to yield a new maximum range for optimum
performance. A lower frequency transducer, such as the
38 kHz model, provides increased power with a longer
wavelength to increase measurement range and improve
performance where steam, vapors or turbulence may be
present.
Technology Advantages and Limitations
The advantages of non-contact sensing are:
•
No contact with corrosive, contaminating liquids.
•
Accurate to within 0.25% of measured span.
•
Continuous and multiple-point sensing available.
•
No moving parts for reduced maintenance.
•
Not affected by changes in liquid properties such as
specific gravity, dielectric shifts, pH, etc.
•
Intrinsically safe, non-incendive and explosion proof
instruments are available.
Conditions limiting ultrasound’s effectiveness include:
•
Surface foam that absorbs the ultrasonic signal.
• Vapors that significantly alter the speed of sound.
•
Operating pressures exceeding 50 psig (3.45 bar).
•
Temperatures exceeding +200° F (+93° C).
I
Real World Applications
Echotel non-contact ultrasonic transmitters have been
engineered to meet the process requirements of major
industries including: Oil & Gas, Chemicals, Food &
Beverage, Power Generation, Pulp and Paper, Water
& Wastewater, Pharmaceutical, and Petrochemical.
Chemical Feed Tanks
Clarifier Level
Influent/Effluent Flow
Fuel Oil Storage
Condensate Storage
Open Atmosphere Sumps
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MAGNETROL [ MAGNETROL INTERNATIONAL, INC. ]
