Suspended Solids - ABB Aztec ATS430 Operating Instructions Manual

4. Press the key (below the Edit prompt).
The Calibration Type screen is displayed:
Calibration Type
1-Point Cal
2-Point Cal
Cancel
5. Use the / keys to select 2-Point Cal and press the
key (below the OK prompt) to start the 2-point
calibration. The Turbidity / Low Solution Value screen is
displayed where the first point value can be entered:
Press the key (below the Next prompt).
Turbidity
Low Solution Value
0.000 NTU
Next
Press the key (below the Edit prompt) to enter the value
of the lower calibration point. Press the
OK prompt). Press the
set the value and display the Second Point Value screen.
6. On the Turbidity / High Solution Value screen press the
key (below the Edit prompt) to enter the value of the higher
calibration point.
Turbidity
High Solution Value
200.0 NTU
Next
7. Place the sensor in the lower calibration solution, press the
key (below the OK prompt), press the
Next and press the
Calibrate
Start Cal?
Place in Low Sol
0.000 NTU
Abort
OK
Edit
key (below the
key (below the Next prompt) to
Edit
key (below the
key (below the Continue prompt).
Continue
The calibration process screen is displayed – the calibration
can be cancelled at any time during the process by pressing
the key (below the Abort prompt):
Calibrate
PV 0.000 NTU
mV -0.00 mV
Settling-Please Wait
Abort
8. When acquisition is complete remove the sensor from the
first calibration point, clean and insert the sensor into the
second calibration point. Clean and dry the sensor
thoroughly, to avoid cross contamination of the calibration
solutions. Press the
start data acquisition.
Calibrate Calibrate
Start Cal?
200 NTU
Abort Abort
9. If the calibration fails a message is displayed indicating the
reason for failure. If the calibration is successful the final
screen displays the new slope. Press the
Exit prompt) to return to the main menu.
The 2-point calibration is now complete.

6.4 Suspended solids

There are 4 possible calibration modes for suspended solids:
— 1-Point calibration: assumes that there is no zero offset,
so a single point is used to calculate the linear relation
between turbidity and suspended solids – refer to
Section 6.4.2, page 18
— 2-Point calibration: two solutions of known suspended
solids concentrations are used to determine the linear
relation between turbidity and suspended solids – refer
to Section 6.4.3, page 19
— In-Process calibration: used in situations where it is not
possible to remove the sensor from the process. A grab
sample is taken from the process for laboratory
determination of the suspended solids content, and the
sensor stores the turbidity value being read at the time
the sample was taken – refer to Sections 6.4.4, page 20
to 6.4.6, page 21
— Manual coefficient: allows the user to input a coefficient
obtained from data analyzed in the lab – refer to
Section 6.4.7, page 22.
Aztec ATS430 | Turbidity sensor | OI/ATS430–EN Rev. H 17
key (below the Continue prompt) to
Continue Continue
key (below the