Liquid Dosing Control Manual
9.17.150 rev A – September 2020
Page
21
of
34
3.3 Verify system status
The system readiness for operation can be checked by monitoring the below parameters
(assuming Idle condition)
Internal temperature sensor
When the internal temperature sensor provides a stable measurement value, then this is an
indication of a stable liquid supply temperature, stable ambient temperatures, and a completion of
the warm-up time of the instrument.
- Read parameter 142 – Temperature
(Temperature in °C)
Please note that upstream temperature changes are not detected by the instrument when there is
no flow. However, the instrument itself can warm up causing a rise in temperature.
Density (Coriolis sensor)
The density measurement provides an indication of any gas trapped in the liquid (bubbles) or a
change in the concentration or composition of the fluid. This measurement is affected by
temperature changes.
- Read parameter 270 – Actual Density
(Density in kg/m
3
)
Example
H
2
O at room temperature
1001.91943359375 kg/m
3
Zero stability
Process or application specific conditions can influence the zero stability. Factors include ambient
temperatures, gas dissolved in the fluid, or switching fluids.
- Read parameter 8 – Measure
(Measure 0 – 32000)
Value 0 corresponds with 0% of the Capacity Value (Full Scale)
Value 32000 corresponds with 100% of the Capacity Value (Full Scale)
or
- Read parameter 205 – fMeasure
(Measure flow)
Value is measurement value in selected Capacity Unit
Please note that small pressure changes up- or downstream can create a flow through the sensor
and can therefore cause an unstable zero-stability (flow measured when no flow should be
present). For calibrating an accurate zero stability it is crucial to prevent this type of flow by
installing shut-off valves.
A pump does not function as a closed valve when the setpoint is 0.
In the next section, the process to execute an Auto-Zero function is described.
Step DDE ProPar Name
Data
Type Execute Value
Remark
1
142
33/7
Temperature
Float read
<temperature> In degrees Celcius
2
270
116/15 Actual Density
Float read
Measured density [kg/m3]
3
8
1/0
Measure
Uint16 read
<measure>
0-32000 = 0-100%
4
205
33/0
fMeasure
Float read
<measure>
In Capacity Unit.
