Level measurement

8 Continuous level measurement in liquids

1. Overview of the measuring principles

Radar Micropilot works with either pulses or with Frequency Modulated Continuous Wave (FMCW). Pulse: High-frequency radar pulses which are emitted by an antenna and reflected from the product surface. The time between pulse launching and receiving is measured and analyzed by the instrument and constitutes a direct measure for the distance between the antenna and the surface of the medium. FMCW: Works with an FMCW continuous electromagnetic wave which is emitted from an antenna and reflected by the product surface. Guided radar Levelflex works with high-frequency radar pulses which are guided along a probe. As the pulse impacts the medium surface, the characteristic impedance changes and part of the emitted pulse is reflected. The time between pulse launching and receiving is measured and analyzed by the instrument and constitutes a direct measure for the distance between the process connection and the product surface. Ultrasonics Ultrasonic measurement is based on the Time-of-Flight principle. A sensor emits ultrasonic pulses, the surface of the media reflects the signal and the sensor detects it again. The Time-of-Flight of the reflected ultrasonic signal is directly proportional to the distance traveled. With the known tank geometry the level can be calculated. positioned in a liquid medium using a servo motor. The displacer is then suspended on a measuring wire which is wound onto a finely grooved drum. When the displacer is lowered and touches a liquid, the weight of the displacer is reduced by liquid buoyancy force. As a result, torque in the magnetic coupling changes, which is measured by 6 Hall sensors. Servo A small displacer is accurately

A

and the time and distance are calculated.

Micropilot Non-contact, maintenance-free measurement also under extreme conditions. Unaffected by density, temperature, conductibility and humidity. No impairment by vapor pressure. •Process temperatures up to +450°C/+842°F • Process pressures up to 160bar/2,320psi Levelflex Reliable and maintenance-free measurement in liquids, also in turbulent media and foam. Unaffected by density, temperature, conductibility and humidity. No impairment by vapor pressure. Measurement of interface and level.

•Process temperatures up to +450°C/+842°F • Process pressures up to 400bar/5,800psi

Prosonic Non-contact and maintenance-free measurement without impairment by

constant, conductivity, density or humidity.

•Process temperatures up to +105°C/+221°F • Process pressures up to 4bar/58psi

Proservo The measurement is unaffected by medium properties like conductivity or dielectric constant and used for custody transfer applications

•Process temperatures up to +200°C/+392°F • Process pressures up to 25bar/362psi