33
6. Ratio Mode
There are two Ratio modes available on the
smart
CHEM
-C
…
•
Absolute Ratio
mode provides a readout of the exact ratio between the two Conductivity
electrodes.
•
Ratio*Standard
mode takes the ratio between the two Conductivity electrodes and multiplies
it by the nominated standard solution value. This effectively provides an absolute readout of
Conductivity and reduces errors due to temperature effects (assuming that the standard and the
sample are at the same temperature).
6.1 Selecting Ratio Mode
1. Plug a k=0.1, k=1.0 or k=10 Conductivity sensor into the
Cond / TDS
socket.
2. Plug a Conductivity sensor
with the same k factor
into the
Ratio
socket. This input is used as
the reference.
3. Select Absolute or Ratio*Standard Mode…
→
→
F3:Mode
→
→
F4:Ratio
→
→
F1:Absolute
or
→
→
F3:Mode
→
→
F4:Ratio
→
→
F3:Ratio*Standard
4. When returning to normal measurement, the
smart
CHEM
-C
will performs a check to ensure
that the two sensors have the same k factor. It also checks if the actual Conductivity of the
signals from each sensor are within the range of measurement of the k factor being used. If
either of these checks fail, the
smart
CHEM
-C
will not proceed to Ratio mode. If this occurs,
press
, then
F3:Mode
, and change back to Conductivity, TDS or Resistivity modes.
5. Having pass the checks above the
smart
CHEM
-C
will now proceed to ratio measurement
mode. Note that the decimal point will be replaced by a “
∗∗
” until a successful calibration has
been performed (see section 6.3).
The following is a sample of absolute ratio mode readout…
1*100
Ratio
25.0
O
C 31/12/03
12:00:00
The following is a sample of ratio*standard mode readout. Note that the
smart
CHEM
-C
still
provides an absolute ratio readout on the top right of the display.
2*86
mS/cm
Ratio
1.100
25.0
O
C 31/12/03
12:00:00
Note that for both Ratio modes, the ratio is expressed as the sensor plugged into the
Cond /
TDS
socket relative to the reference sensor plugged into the
Ratio
socket.