The advantages of Endress + Hauser's guided radar level measurement device have been clearly proven at a European manufacturing plant.
Despite sales of more than 20 000 units worldwide since the introduction of the technology in 1998, guided radar level measurement is still perceived by some to be a relatively young development. Endress + Hauser believes that its new Levelflex M is set to remove any doubts with regard to the clear benefits that this methodology brings.
The installation of Levelflex M came during the extension of a profile system production plant in Pirmasens, Germany. This facility manufactures window, door and visual protection systems for worldwide export, as well as plastic sheets and construction profiles. PVC material forms an integral part of the manufacturing process.
PVC powders are known to present a challenge to level measurement devices, because of their bulk density being around 0,55 kg/l, coupled with a very low dielectric constant of 1.6. Making matters worse, extreme dust development in the slender and high silos in Pirmasens makes dependable measurement by ultrasonic or electromechanical level systems, particularly in pneumatic filling, almost impossible.
Featuring a measuring range of up to 35 m and a dielectric constant from 1.6, Levelflex M is capable of solving complex application headaches. The innovative device measures level in bulk solids and liquids according to the physical principle of radar pulse technology, based on time domain reflectometry (TDR). This allows its guided radar pulses to pass through the dust as easily as it would foam, in a liquid application. After a test phase, the Pirmasens plant undertook to equip 10 new raw material silos of 26 m in height and 3 m in diameter with the new instruments.
Levelflex M uses a brief electromagnetic pulse (width of nanoseconds), which is induced onto the probe or rod via antenna electronics. This results in 'packages of energy' running along the probe at close to the speed of light, each with a diameter of 300 mm. As the pulse meets the product surface, the characteristic impedance changes. Part of the transmitted pulse is reflected in dependence on the dielectric constant of the medium and scanned by a high-frequency sampler. The distance between the process connection and the product surface in the silo is calculated by the time elapsed between the signal and the reflected pulse. Since the radar pulses are guided along the rod, the measurement is not influenced by baffles. This greatly extends the range of applications of time-of-flight methods for liquids and solves the problem that foam has often represented to radar and ultrasonic measuring devices.
A further advantage to the new Endress + Hauser device is that, with a coax probe, media can be detected at a dielectric constant of only 1,4, making it suitable for complicated container geometries and turbulent medium surfaces.
Uniquely, Levelflex M represents signal progression as an envelope curve directly on the instrument display. This is a novelty for purposes of a plausibility check. The operating tool (time-of-flight) is free of charge and facilitates simple commissioning; diagnosis and detailed measuring point documentation directly at the control room. Levelflex M's modular design and its exchangeable rope secures the highest degree of flexibility and reduces storage costs. The new rope construction also lowers ceiling stress by up to 50%.
For more information contact Grant Joyce, Endress + Hauser, 011 262 8000, [email protected], www.za.endress.com
| Tel: | +27 11 262 8000 |
| Fax: | +27 11 262 8062 |
| Email: | [email protected] |
| www: | www.endress.com |
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