Compact transmitters for non-contact level
measurement
Application
• Continuous, non-contact level measurement in fluids, pastes, sullages and coarse
bulk materials
• Flow measurement in open channels and measuring weirs
• System integration via:
– HART (standard), 4 to 20mA
– PROFIBUS PA
– FOUNDATION Fieldbus
• Maximum measuring range:
– FMU40: 5 m (16 ft) in fluids, 2 m (6.6 ft) in bulk materials
– FMU41: 8 m (26 ft) in fluids, 3,5 m (11 ft) in bulk materials
– FMU42: 10 m (33 ft) in fluids, 5 m (16 ft) in bulk materials
– FMU43: 15 m (49 ft) in fluids, 7 m (23 ft) in bulk materials
– FMU44: 20 m (66 ft) in fluids, 10 m (33 ft) in bulk materials
Features and benefits
• Quick and simple commissioning via menu-guided on-site operation with four-line,
multilingual plain text display
• Envelope curves on the on-site display for simple diagnosis
• Easy remote operation, diagnosis and measuring point documentation with the free
operating program FieldCare supplied.
• Suitable for explosion hazardous areas
(Gas-Ex, Dust-Ex)
• Linearization function (up to 32 points) for conversion of the measured value into
any unit of length, volume or flow rate
• Non-contact measurement method minimizes service requirements
• Optional remote display and operation (up to 20 m (66 ft) from transmitter)
• Installation possible from thread G 1½“ or 1½“ NPT upwards
• Integrated temperature sensor for automatic correction of the temperature
dependent sound velocity
Time-of-flight method
The sensor of the Prosonic M transmits ultrasonic pulses in the direction of the product surface. There,
they are reflected back and received by the sensor. The Prosonic M measures the time t between pulse
transmission and reception. The instrument uses the time t (and the velocity of sound c) to calculate
the distance D between the sensor membrane and the product surface:
D = c t/2
As the device knows the empty distance E from a user entry, it can calculate the level as follows:
L = E – D
An integrated temperature sensor (NTC) compensates for changes in the velocity of sound caused by
temperature changes.
Interference echo suppression
The interference echo suppression feature on the Prosonic M ensures that interference echos (e.g.
from edges, welded joints and installations) are not interpreted as a level echo.
Calibration
Enter the empty distance E and the span F to calibrate the device.
Blocking distance
Span F may not extend into the blocking distance BD. Level echos