Thermo Fisher Scientific Alpha TDS 200 - Manual (Page 14)

10
6 TDS CALIBRATION
IMPORTANT: When Calibration mode is entered, controller automatically goes into a
“HOLD” mode where the 4-20 mA output freezes and relays are de-activated (if it was in
an activated condition). Upon return to measurement mode, both 4-20mA output and
relay activities resume, depending on settings.
The TDS 200 controller allows one-point slope calibration in one of its eight total
dissolved solids measurement ranges.
Choose fresh standard solutions, whose value is reasonably close to the measurement
value.
Before calibration, make sure electrode is clean. Use iso-propyl alcohol followed by
thorough rinsing in distilled water to clean electrode.
Important: To achieve a successful TDS calibration, two conditions must be satisfied:
1. Difference between measured value of standard solution, and actual value of
standard solution, must be within ± 40 %.
(e.g. if value of standard solution is 500 ppm, then allowable measured
values by controller must be within 700 ppm {+ 40%} and 300 ppm{- 40%});
and
2. the lowest possible value must be at least 10% of full scale
(e.g. if range of 0 to 1000 ppm is selected, min. measured value at
calibration, must be at least 100.0 ppm).
If any or both conditions are not satisfied, controller will display ERR 1 (blinking).
1.
Key in the password “011” using the method described in Section 5.
2. Controller flashes the value of the standard solution.
3. Use electrode to agitate standard solution to obtain a homogeneous solution and
to dislodge any bubbles. Allow electrode time to stabilize with solution temperature.
4. Use ▲/ ▼keys to adjust displayed readings to the value of the standard solution.
Press ENTER.
5. If any of the two conditions mentioned above is not satisfied, controller will display
ERR1, blinking.
6. If calibration is successful, Controller displays DONE, blinking. Press ENTER to
revert to TDS measurement mode (Relays and 4-20 mA output resume activities
as per previous settings).