A transmitter is required to measure the liquid level in an agitated tank. Which of the following technologies are not indicated for this application?
B. Differential pressure
C. Guided wave radar
D. Noncontact radar
Capacitance and guided wave radar level instruments involve probes that are in contact with the liquid and would interfere with the operation of the agitator so Answers A and C would not be indicated for this application.
Additional complicating factors
The remaining technologies can have their disadvantages. For example, a differential pressure level transmitter signal may exhibit some oscillation due to the rotation of the agitator. Damping the signal should resolve this issue. Noncontact radar and ultrasonic level transmitters typically have software that can ignore the passing of the agitator; however, the measured level may or may not represent the true tank level due to the intensity of agitation.
David W. Spitzer is a principal at Spitzer and Boyes, LLC, which offers engineering, focused market research, writing/editing white papers, strategic marketing consulting, distribution consulting, seminars and expert witness services for manufacturing and automation companies. Spitzer has written more than 400 technical articles and 10 books about flow measurement, instrumentation and process control. He can be reached at 845-623-1830 or via spitzerandboyes.com.