Level measurement

122 Continuous level measurement in bulk solids

4. Instrument selection within the measuring principle

Guided radar

Required application data Level measurement • Measuring range • Consider ceiling load by max. tensile force at the point of measurement • Calculation of tensile force by Endress+Hauser

Application limits for guided level radar • (higher temperatures upon request)

• • (longer upon request) •

• DC value (DC) of the product • Pressure and temperature • Resistance requirements • Existing nozzle diameter: DN, PN, nozzle height

Dielectric constant (DC) The reflection properties of a medium are determined by the dielectric constant (DC).

Max. measuring range

Media group

DC

Typical bulk solids

Metallic uninsulated probes

PA-coated rope probes

20 to 25m/ 66 to 82ft 25 to 30m/ 82 to 99ft 30 to 45m/ 99 to 148ft

C

1*

1.4 to 1.6 • Plastic powder

—

• Plastic granulates • White lime, special cement • Sugar

12 to 15m/ 39 to 49ft

2

1.6 to 1.9

• Cement, gypsum

—

3

1.9 to 2.5

15 to 25m/ 49 to 82ft 25 to 30m/ 82 to 99ft 25 to 30m/ 82 to 99ft

• Flour

—

• Cereal, seeds

—

4

2.5 to 4

• Ground stones • Sand

45m/148ft

• Naturally moist (ground) stones, ores • Salt

5

4 to 7

45m/148ft

35m/110ft

• Metal powder • Carbon black • Carbon dust

6

>7

45m/148ft

35m/110ft

For very loose or loosened bulk solids, the respectively lower group is applicable. Reduction of the max. possible measuring range by: • solids with a low density in case of pneumatic filling • Build-up formation, particularly of humid products.

* Media group 1: Take into account restrictions for strongly damping media