Prosonic S FDU90/91/91F/92/93/95/96
Hauser
3
Function and system design
Measuring principle
L00-FMU90xxx-15-00-08-xx-900
1
FDU9x
2
Prosonic S FMU90
BD:
blocking distance,
D:
distance from sensor membrane to fluid surface,
E:
empty distance
F:
span (full distance),
L:
level,
V:
volume (or mass),
Q:
flow
Time-of-flight method
The sensor transmits ultrasonic pulses in the direction of the product surface. There, they are reflected back
and received by the sensor. The transmitter Prosonic S measures the time t between pulse transmission and
reception. From t (and the velocity of sound c) it calculates the distance D from the reference point (see the
figure
D = c · t/2
From D results the desired measuring value:
• Level L
• Volume V
• Flow Q across measuring weirs or open channels
Time-of-flight correction
In order to compensate for temperature dependent time-of-flight changes, a temperature sensor (NTC) is
integrated in the ultrasonic sensors.
100%
0%
D
L
F
E
BD
V
Q
D
1
2
2
1
Sensor
BD
Maximum range
fluids
Maximum range
bulk materials
FDU90
0.07 (0.2)
3 (9.8)
1.2 (3.9)
FDU91 (F)
0.3 (1.0)
10 (33)
5 (16)
FDU92
0.4 (1.3)
20 (66)
10 (33)
FDU93
0.6 (2.0)
25 (82)
15 (49)
FDU95 (low temperature version)
0.7 (2.3)
45
(148)
FDU95 (high temperature version) 0.9
45
(148)
FDU96
1.6
70
(230)
m (ft)
