AMALGAMATED INSTRUMENT PM4-CO, Инструкция по эксплуатации

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6 Calibration
6.1 Introduction
The instrument has provision for calibration slope and head resistance compensation conductiv-
ity/resistivity/ppm calibration. A null calibration feature (see
CALNULL
) allows the probe to be
referenced to the instrument at a zero conductivity level. A null calibration should be undertaken
before a single or two point calibration to ensure that the probe and instrument are matched.
Before calibrating the instrument it is also important to ensure that the correct cell constant has
been chosen. The
CAL1
together with the
CAL NULL
function sets the calibration slope, the
CAL2
reading is used to compensate for head resistance when long cable lengths are used. When
using a temperature probe temperature calibration is carried out with the
"CNULL
and
CAL"C
functions, ensure that the correct temperature probe type has been selected (see
"C tYPE
) and
that the appropriate links have been set (see Chapter 3 ).
6.2 Calibration Functions
To enter the calibration mode the instrument must be powered up and functions entered via
CAL
mode as illustrated in chapter 5 page 20 .
6.3 Conductivity/Resistivity/ppm Calibration Null
Null calibration allows the cell to be referenced to the meter. The instrument should be nulled
before calibration. To null the instrument the following procedure should be followed.
1. If a temperature compensation sensor is used check that the temperature reading is correct
and calibrate the temperature reading if necessary, see “Temperature Calibration Null” and
“Temperature Calibration” sections in this chapter. Also check that the
SOLSLPE
function
is correctly set. If no temperature sensor is being used check that the
SOL "C
function is
set to the required default temperature.
2. Using pure water clean the cell to be nulled, dry the cell and place in air.
3. Enter the
CAL
mode and
FUNC
mode then step through the functions until
CAL NULL
is
displayed.
4. Press
^
and
v
together, the display will show a reading (this reading will be taken as zero
upon completion). Allow 20 seconds for the reading to stabilise.
5. Press
F
, the display will show
NULLEnd
. When the instrument returns to normal measure
mode the reading from the probe in air will be zero. If any other message is seen refer to
section
6.13 .
6.4 Conductivity/Resistivity/ppm Calibration
After performing the null calibration as previously described place the required probe in a solution
of known conductivity/resistivity (for resistivity calibration ensure that the calibration solution
resistivity is not above 1MΩ) or ppm. Follow the procedure below.
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