BioProTT
TM
Flow Measurement System
Version 1.00
page 35 of 75
7.6
Zero Adjustment
Zero adjustment must be carried out before the start of every measurement to avoid
possible offsets of measured values.
When doing this, the transducer should be clamped at the right location on the tube. The
tube must be filled with fluid and the fluid must be at stationary. Make sure that there are
no air bubbles in the tube.
Also allow sufficient time to adjust for a stable temperature profile.
The system is now ready for a measurement or custom calibration by adjusting the
calibration factor if needed (see chapter CUSTOM CALIBRATION PROCEDURE).
7.7
Performing Flow Measurements
7.7.1
Measurement Using the Analog Interface of BioProTT™
Flow
Track,
BioProTT™
Flow
Track plus and BioProTT™
Flow
Track DINrail
The flow meter can be connected to data acquisition or process control systems with the
analogue interface. The flow meter has two analogue interfaces for transmitting the Flow
and RSS (acoustic coupling) values. The values are transmitted within the range of (0)4-20
mA, the value of 0.2-0.3mA indicates a circuit error, the value of 0 mA is used to indicate
an error or a broken cable respectively broken circuit.
7.7.1.1 Received Signal Strength (RSS / Acoustic Coupling)
The software maps the RSS value from 0-100% linearly to 4-20 mA:
4 mA equals 0% coupling / received signal strength (or no signal)
20 mA equals 100% RSS (excellent signal).
The RSS value should be at least 13,8 mA (or > 60%). This indicates a good signal and
will ensure accurate flow measurements.
If the tube is too small or the transducer is too large, or there is no liquid or bubbles in the
tubing this can also explain why the coupling is insufficient. Make sure that the tube fits
the transducer you are using
.
Also follow the procedure described in chapter
INSTALLATION OF THE BIOPROTTTM CLAMP-ON TRANSDUCER when clamping
the sensor onto the tube.