Hach EC1000, Инструкция по эксплуатации

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2.3.1.2 One-Point Grab Sample Calibration
Note: When Solution
Temperature
Compensation is
operational (non-zero, see
Section 2.2.5 Initial Setup)
the current pH value saved
and displayed in Step 3 is
the actual pH of the
process solution at the
process temperature. For
best accuracy, the lab
sample reading should be
taken at the same
temperature as the
process sample reading.
This method is used to do a one point (offset) pH calibration using a grab sample
comparison of the process solution measured on a calibrated laboratory or portable pH
meter. This calibration is not as accurate as the two point calibration because it only
corrects the offset, and does not adjust the slope. A special feature of this calibration is that
the pH electrode readings are saved at the time the grab sample is taken (see Step 3). This
allows for an accurate calibration even if the pH of the process stream changes during the
time used to measure the sample on a laboratory meter.
1. Press
CAL
to call up the main calibration menu. The display shows:
2. Press the
DOWN ARROW
key to proceed to:
3. Take a sample of the process solution and then press
ENTER
. When the enter key is
pressed, the current pH value is saved and displayed on the readout with the first
digit flashing.
4. Measure the pH of the sample on a calibrated lab meter.
5. Edit the value on the display to match the lab reading by pressing the
RIGHT ARROW
key and the
DOWN ARROW
key or the
UP ARROW
key.
6. Press
ENTER
to accept the calibration.
7. Press
pH/mV
to return the meter to normal operations. The pH reading may be different
from the value just entered. This occurs if the pH of the process stream changes from
the time the grab sample was taken in Step 3. For example, if the pH of the process
stream increases by 0.15 pH during the time between Step 3 and Step 6, the current
reading should be 0.15 pH higher than the value entered in Step 5.
2.3.1.3 Calibration Procedure Variations
Manual Entry of Buffer Value
Note: The Auto recognition
function is valid only when
using the following Hach
buffers: pH 4.01, pH 7.00,
or pH 10.00. If buffers
other than those listed are
used, the buffer value must
be entered.
Use two buffers in the range of 0 to 14 pH that are at least 1 pH unit apart for calibration.
You may use one auto and one manually entered buffer or two manually entered buffers
for calibrations. The order in which the buffers are used has no effect on the calibration.
To use manual entry of buffer value(s), replace Step 6 and/or Step 10 with the
following procedure.
1. Press the
DOWN ARROW
key to scroll to the manual entry. The display shows:
2. Press
ENTER
. The readout is an edit display with a pH value such a 6.97 PH. (The
last value used is displayed.) The lower display shows the current temperature of
the buffer.
3. After the temperature reading stabilizes, use the temperature reading and the chart
provided with the pH buffer to determine the actual buffer value.