Level measurement

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Continuous level measurement in bulk solids

4. Instrument selection within the measuring principle

Ultrasonics

Required application data • Measuring range • Product grain size • Product surface (soft, hard)

Application limits for ultrasonic level measurement in solids • Temperature up to –40°C/–40°F • Temperature up to +150°C/+302°F (higher temperatures on request) • (relative) • conditions) • • Strong temperature fluctuations in the measuring range can affect the accuracy

• Dust-generating product (strong, low) • Filling curtain in the measuring range • Nozzle diameter/nozzle height • Pressure and temperature

Damping caused by process

Product surface

Filling curtain in the detection range

40dB

None

0dB 5dB

C

40 to 60dB

Small quantities Big quantities

dust-covered clinker)

5 to 20dB

Dust

product surface

No dust generation Low dust generation Strong dust generation

0dB 5dB

Up to 20°C/68°F Up to 40°C/104°F Up to 80°C/176°F

0dB

5 to 10dB

5 to 20dB 10 to 20dB For different applications, the max. measuring distance can be estimated from the sum of dampings (dB) and the range diagram (see also example below).

Range calculation and sensor selection Prosonic S FDU9x

R [m/ft]

Example (for FDU91): • Silo with rubble: • Low dust generation: • Small quantities of filling curtain in the detection range: Total: +50dB range approx. 5m/16ft from diagram

45/148

+40dB +5dB +5dB +50dB

FDU95

25/82 20/65

FDU93 FDU92

10/32

FDU91 (F) FDU90

3/9.8

0

20 40 60 80 100 A [dB]

0