Level measurement

130

Continuous level measurement in bulk solids

4. Instrument selection within the measuring principle

Installation instructions – ultrasonics

Installation • Not centered [3] • Not above filling curtain [4] • 20cm/7.9" [1] • If 2 or several sensors are used in one vessel, please use separate instrumentation (FMU90/95 + FDU9x) Weather protection cover • Always recommended for installation outside (solar radiation and rain) [2] Nozzle • The sensor diaphragm should protrude from the nozzle. If this is not possible, please compare the dimensions of the nozzle with the table: Nozzle length (next page) Measuring range • Measurement is possible up to the blocking distance (BD) on principle • The measuring range starts where the ultrasonic lobe meets the bottom of the silo. In dished or torispherical heads or conical outlets, levels below this point cannot be detected Silo baffles • Make sure that baffles [1] like limit switches, struts, etc. are not within the beam cone (see also the beam angle table in this respect [a]) • impair measurements Optimizing measures • Use a sensor with a smaller beam angle. The smaller the beam angle the lower the occurrence of interfering echoes • Interference echo suppression: Electronic suppression of interfering echoes optimizes the measurement • Plates installed in an inclined manner [3] disperse the signal and can avoid interfering echoes Alignment • Serves the avoidance of interfering reflections and improved measurements since the measurement can be aligned to the angled surface (accessory FAU40 or assembly bracket)

C

FMU 40

FMU 41

FMU 42

FMU 43

FMU 44

FDU 90 12° 1.2/ 3.9

FDU 91

FDU 91F 12°

FDU 92 11° 10/ 32

FDU 93

FDU 95

Beam

11°

11°

9°

6°

11°

9°

4°

5°

L max (m/ft) r max (m/ft)

2/ 6

3.5/ 11

5/ 16

7/ 22

10/ 32

5/ 16

5/ 16

15/ 49

45/ 150

0.19/ 0.6 0.25/ 0.8

0.34/ 1.1 0.35/ 1.15

0.39/ 1.3

0.37/ 1.2

1.96/ 6.4

0.13/ 0.4 0.07/ 0.23

0.39/ 1.3

0.53/ 1.7

0.96/ 3.1

0.52/ 1.7

1.96/ 6.4

Blocking distance (m/ft)

0.4/ 1.3

0.6/ 2

0.5/ 1.6

0.3/ 1

0.3/ 1

0.4/ 1.3

0.6/ 2

0.7/2.3 (0.9/ 2.9 * )

* High temperature = 150°C/302°F