Hach EC1000, Инструкция по эксплуатации

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Note: The temperature
difference between the
two samples must be at
least 10 °C.
10. Move the electrode to a sample at a different known temperature.
11. Press
ENTER
. The readout is an edit display with a temperature value such as 60.0 °C.
(The value displayed is the last value used.)
12. Edit the value on the display to match the temperature of the sample by pressing the
RIGHT ARROW
key and the
DOWN ARROW
key or the
UP ARROW
key.
13. Press
ENTER
. The readout displays the current temperature measurement.
14. After the electrode stabilizes (refer to the stability indicator note in Section 2.3
Calibration), press
ENTER
to accept this calibration point.
15. Press the
pH/mV
key to return the meter to normal operations.
2.3.3 ORP Calibration/mV Zero
Note: Although the Light’s
Solution Ampule contains
enough solution for several
calibrations, reusing the
solution is not suggested
due to potential
contamination. Hach
Company recommends
discarding the remaining
solution after use.
The mV zero is used for ORP measurements. This entry allows for ORP calibrations and
for the mV reading to be offset to a desired value.
To calibrate the ORP electrode, the offset of the internal preamp must be zeroed, and then
the electrode must be standardized in a solution of known redox potential. Hach offers
Light’s Solution (Cat. No. 26125-20) as an ORP standard in 20-mL glass ampules sealed
under argon. Or, you may prepare your own solutions as described in Table 4.
2.3.3.1 Preamp Zero
1. Connect one end (pin) of the ORP Shorting lead to the reference pin connector at the
top of the electrode. Touch the other end directly to the platinum disc of the ORP
Sensor, see Figure 5 on page 23.
2. Press
CAL
to call-up the main calibration menu. The display shows:
3. Press the
UP ARROW
key. The display shows:
4. Press the
ENTER
key. The readout is an edit display such as 0.0 mV. (The value
displayed is the last value used).
5. Edit the value on the display to read 0.0 by pressing the
RIGHT ARROW
key and the
DOWN ARROW
key or the
UP ARROW
key.
Table 4 Preparation of Redox Standard Solutions
Standard
Solution
Hach ORP
Electrode Pt Electrode
vs. SCE
Pt Electrode
vs. SHE*
Weight per 1000 mL Solution
at 25 °C
Light’s
Solution
446** mV 430 mV +675 mV 39.21 g ferrous ammonium sulfate,
Fe (NH
4
)
2
(SO
4
)
2
• 6H
2
O
48.22 g ferric ammonium sulfate,
Fe (NH
4
) (SO
4
)
2
• 12H
2
O
56.2 mL sulfuric acid, sp gr 1.84
Zobell’s
Solution
215 mV 183 mV +428 mV 1.4080 g potassium ferrocyanide,
K
4
Fe (CN)
6
• 3H
2
O
1.0975 g potassium ferricyanide,
K
3
Fe (CN)
6
7.4555 g potassium chloride, KCI
* SHE = Standard Hydrogen Electrode.
** The deviation from 32.0 mV versus SCE is due to conventional junction potentials produced by the high
ionic strength of Light’s Solution.