VWR 662-2380, Инструкция по эксплуатации

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Calibration with use of one solution does not guarantee high accuracy. If only
one solution is used, its value should be close to the anticipated value of the
measured solution. If the required accuracy isn’t very high and the
measurements are made in the whole range, 1-point calibration should be
performed with use of solution close to 7.00 pH. It enables to avoid an error
resulting from so called zero offset of the electrode. In other points the meter
adopts standard characteristic from the memory.
The solutions may be used randomly. In
PH-2500L the electrode
characteristic is approximated linearly between the calibration points.
Entering the calibration mode erases the electrode’s characteristic
stored under the chosen number.
There is no possibility to calibrate the electrode only in one point with
leaving the rest of the data from the previous calibration.
The characteristic erase is signalised by red colour of the electrode number.
10.1. Calibration in buffer or standard solutions
Before starting the calibration process, prepare the meter according to the
chapter 6 and decide whether the calibration will be performed with use of
buffer or standard solutions.
The calibration may be performed in two following methods:
1. Entering the values of currently used pH buffers to the meter’s
memory; calibration is performed in these buffers.
2. Using the pH standard solutions values entered to the memory by
the manufacturer (NIST norm conformity). Choosing this type of
calibration automatically enables correction connected with the
temperature influence on the standard’s value. As a result, there is
no need to adjust the standard’s temperature or to enter the
standards’ pH values corresponding with different temperature
values.