Figure 8: The Mix Cycle With Pre-Wet - Hydronix Hydro-Control VI Operator's Manual

Chapter 4
The Mix Cycle when using Pre-wet Water
2.4
The mix cycle when using Pre-wet Water is shown, along with a typical moisture trace, in Figure
8.
Moisture
Signal
increases
from mixer
empty
reading.
As water is
added the
signal
increases
further.
Pre-wet Water
Load
Mix Phase
mixer Addition
Signals
From PLC
START
CEMENT IN*
To PLC
PRE-WET*
DONE
MIX
COMPLETE
*Optional Signals
The Hydro-Control VI starts its cycle when the "Start" signal is received. The first phase is the
addition of the Pre-wet Water followed by the mix time defined in the parameter "Pre-wet Mix
Time". The "Pre-Wet Done" output then goes high and, if enabled, the Hydro-Control pauses
until the "Cement In" input is activated (the Cement Timeout parameter in the recipe must be
set to enable the "Cement In" input).
The next phase is the dry mix time, set in the recipe. After this period, water is added, after
which the wet mixing time commences, also set in the recipe. At the end of the wet mix time
the cycle is finished and the "Mix Complete" signal is set, which signals the batch control PLC
to unload the mixer.
The Mix Cycle when using Initial and Pre-wet mix phases
2.5
In some mix designs it may not be possible, or take an undesirable amount of time, to obtain a
stable reading in the dry or wet mix once certain materials or chemicals are added. Reasons
may include:
Using metal fibres
•
As materials mix
As the
the signal
materials
continues to
mix with
stabilise. A
the water
stable signal
the signal
indicates that all
starts to
the materials are
stabilise.
mixed thoroughly
and the mix is
homogeneous.
Pre-wet
Dry Mix Time
Mix Time

Figure 8: The mix cycle with pre-wet

Understanding the Mix Cycle
As the water
gets mixed
the signal
begins to
stabilise. A
stable signal
indicates that
As more
all of the
water is
water is
added the
mixed to
signal
homogeneity.
increases
again.
Main Water
Wet Mix Time Discharge Mixer
Addition
Hydro-Control VI Operators Guide HD0456 Rev 1.7.1
As the mixer is
discharged the
signal reduces
back to the mixer
empty reading.
Time
23