Hydronix Hydro-Control VI, Operator'S Manual

Page: 47 / 88

Chapter 8 Using Moisture Control
Hydro-Control VI Operators Guide HD0456 Rev 1.7.1 47
It is important that there is sufficient difference between the sensor reading taken at the end of
the dry mix phase and the sensor reading taken at the end of the wet mix phase, to give a good
moisture range for the calibration calculation.
Figure 20: The calibration failed error message
The Hydro-Control requires the difference between the two readings to be greater than 4
unscaled (this is approximately 1% moisture). If this is not the case then the error message
shown in Figure 20 is displayed. It is necessary to reduce the amount of pre-wet water going
into the mixer or to use drier aggregates.
The deviation of the signal during each of the dry and wet mix averaging phases must be
minimal in order to give a correct average value for the calculation. The deviation is displayed
on the Mix Log screen, when viewed as unscaled units the value should be less than 3
unscaled, and preferably below 0.5.
Moisture
Time
B
A
Figure 21: Comparison of averaging times
From Figure 21, it can be seen that if the signal is not averaged, then the instantaneous value
taken for the calculation could be, as an example, at point A or point B and would not be
representative of the moisture in the mixer. Therefore it is important to average the signal and
to make sure that the averaging time is set correctly. A longer averaging time will give a better
average reading but will also extend the mix time. In normal circumstances a typical averaging
time would not be greater than 10 seconds.
After a calibration has been set, the system should be monitored for at least two more mixes to
check that the system is correctly compensating for changes in the dry moisture.
2.10
Selecting the Sensor Measurement Mode
When connected to a compatible sensor the Hydro-Control will log all available Measurement
Modes (see Sensor Configuration and Calibration Guide HD0679 for more details). Each
Measurement Mode uses a different method to calculate the Unscaled and as result the dry
and wet mix values can differ. This difference enables the user to select the most appropriate
Measurement Mode to produce a stable mix it may also increase the difference in Unscaled
between the dry and wet mix phases.
When selecting the Measurement Mode it is necessary to inspect the Mix Trace for each mode
to confirm that the signal is stable in the dry and wet mix phases. It is also important to confirm
that the Unscaled value does not go above 100.
In Figure 22 three Measurement Modes are displayed. All three Measurement Modes are stable
and do not go above 100 Unscaled. However, the blue trace has the greatest difference
between the dry and wet mix phase so is selected to be used for the calibration.
For advice on selecting the Measurement mode contact the Hydronix support team at
support@hydronix.com