Level measurement

118 Continuous level measurement in bulk solids

4. Instrument selection within the measuring principle

Radar

Required application data • Measuring range (min/max) • DC value of the medium (DC)/ media group • Grain size • Nozzle diameter/nozzle height • Pressure and temperature Application limits for level measurement by radar instruments in bulk solids • Temperature up to –40°C/–40°F

Dielectric constant (DC) The reflection properties of a medium are determined by the DC value. The following table describes the allocation of different DC values to groups of media. For very loose or loosened bulk solids, the respectively lower group is applicable.

• • • •

Aerosil, Perlite

Typical applications

•

C

Endress+Hauser App für DK-Werte Die App bietet einen bequemen Zugang zu mehreren tausend DK-Werten für viele unterschiedliche Medien.

Special features

Dielectric constant (DC value) Compendium

Media group DC value Examples A

Technical data • Process pressure • Process temperature* • Antenna type

1.6 to 1.9 Plastic granulate, white lime, special cement, sugar

B

1.9 to 2.5 Cement, gypsum

C

2.5 to 4 Cereal, seeds, ground stones, sand

D

4 to 7

Naturally moist (ground) stones, ores, salt Metal powder, carbon black, carbon dust

• Max. Measuring range

E

>7

• DC value • Accuracy • Process

Reduction of the max. possible measuring range by: • Media with poor reflection properties (low DC value) • Large angle of repose •

connection

• Process-contacting materials

pneumatic filling. Please use the respectively lower media group in this case • Build-up formation (particularly if moisture is present in the process)