7
2. Limits Set-up
The limits must be set to the required values before attempting to use the
hydro
CHEM
for
automatic control.
2.1 Setting the Control Limits
1. Select the Limits menu (
→
→
F3:Limits
).
2. Select
F1:Set limits
from the menu. The current Conductivity limit is displayed. For
example…
Enter Conductivity Limit : 2.0 mS/cm
Use the
and
keys to set the Conductivity limit. The allowable range is 0.0 to 9.9 mS/cm.
Press
to save the new value, or press
to quit without saving the changes.
3. The current pH limit is now displayed. For example…
Enter pH Limit : 6.5pH
Use the
and
keys to set the pH limit. The allowable range is 0.0 to 14.0 pH.
Press
to save the new value, or press
to quit without saving the changes.
4. The control limits are now set to the required values.
2.2 Control Direction
The
hydro
CHEM
is factory set to add nutrient when the Conductivity reading is lower than the
limit, and to add acid when the pH reading is higher than the limit. To change these settings…
1. Select the Limits menu (
→
→
F3:Limits
).
2. Select
F2:Direction
from the menu. The following screen will now be displayed…
Select Conductivity Direction
→
→
F1:Add when LOW F2:Add when HIGH
The arrow indicates the current selection.
Press
to add nutrient when the Conductivity reading is lower than the limit.
Press
to add freshwater when the Conductivity reading is higher than the limit.
3. The
hydro
CHEM
confirms the selection and then goes on to select the pH Direction…
Select pH Direction
F1:Add when LOW
→
→
F2:Add when HIGH
The arrow indicates the current selection.
Press
to add alkali (eg. Soda Ash) when the pH reading is lower than the limit.
Press
to add acid when the pH reading is higher than the limit.
4. The
hydro
CHEM
confirms the selection before going back to the Limits menu.
