One Point Calibration With A Buffer; Calibration Review; Temperature Calibration - Hach EC1000 Instruction Manual

2.3.1.4

One Point Calibration with a Buffer

2.3.1.5

Calibration Review

2.3.2 Temperature Calibration

s
4. Edit the value on the display by pressing the
key or the
ARROW UP ARROW
5. Press . The readout displays the current pH value.
ENTER
To calibrate the instrument with one buffer and a one point calibration, follow the
procedure for a two point calibration with buffers, omitting Steps 8-11.
The calibration review menu entry is used to track the performance of the electrode. The
menu entries are OFFSET, SLOPE, STD 1, and STD 2. The offset is a measure of the mV
reading when the electrode is at pH 7. The ideal offset is 0 mV. The slope is a measure of
the mV/pH at 25 °C, with the ideal slope being 58 mV/pH. For new electrodes, the offset
should be 0 ±35 mV, and the slope should be 58 ±2 mV. For normal calibration, the meter
accepts an offset in the range of ±100 mV and a slope in the range of 50.6 to 71.2 mV.
STD 1 and STD 2 entries recall the standard(s) used for the last calibration.
The uncalibrated accuracy of the temperature sensor is ±1.5 °C and temperature
calibration is normally not required. If greater accuracy is required, use the following
procedure for either a one point or a two point calibration. The calibration temperature
should be near the anticipated operating point for a one point calibration, or bracket the
anticipated operating range and be at least 10 °C apart for a two point calibration.
1. Remove the electrode from the sample cell.
2. Place the electrode in a sample of known temperature.
3. Press to call up the main calibration menu. The display shows:
CAL
4. Press the
UP ARROW
5. Press . The display shows:
ENTER
6. Press . The display will show:
ENTER
The readout is an edit display with a temperature value such as 0.0 °C. (The last value
displayed is used.)
7. Edit the value on the display by pressing the
key or the
UP ARROW
8. Press . The readout displays the current temperature of the sample.
ENTER
9. After the electrode stabilizes (refer to the stability indicator note in Section 2.3
Calibration), press
ENTER
calibration, omit Steps 10-13.
RIGHT ARROW
key so the display matches the buffer value.
key twice. The display shows:
RIGHT ARROW
key so that the display matches the sample temperature.
to accept the calibration point. If this is a one point
41
key and the
DOWN
key and
DOWN ARROW