Metrohm 781 pH/Ion Meter - Manual (Page 67)

6 Methods / Parameters
780/781 pH/Ion Meter, Manual
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Please note that the drift condition defined here and the temperature
parameter described below do not apply to the calibration and, if nec-
essary, must be set separately under the calibration parameters.
temperature -999.9...25.0...999.9 °C
This menu item only appears when no temperature sensor is connect-
ed. In this case you can enter the temperature of the sample solution
here. If the measuring and calibration temperatures are different then it
is necessary to record the temperature for the automatic correction of
the electrode slope (temperature compensation, see Section 9.2.1). In-
formation about the measuring temperature is also absolutely neces-
sary for the complete documentation of a pH value. In the report
printout of the measured value this manually determined temperature is
indicated by the suffix ' manual '.
method 8 ASCII characters
All parameter settings can be stored together or loaded as a method
(see Section 6.1). The name of the current method is then given here.
This field is only used for information here and cannot be edited direct-
ly.
delta measurement ON, OFF
The delta measurement permits the display of the measured value rela-
tive to a freely selectable constant reference value:
reference pH -19.999...0.000...19.999
This reference value is subtracted from the measured value itself. The
modified measured value is shown together with this value and is taken
into consideration, for example, in checking the limit values (see PA-
RAMETER pH/limits pH ). The reference value is not included in the
report. However, should you still want to document it then you should
also produce a parameter report (see Section 7.2.7).
stirrer: ON, OFF, control
You can choose whether the pH measurement is to be made while stir-
ring is being carried out or not. A requirement is that a Metrohm stirrer
is connected with a suitable cable (see Section 2.3). If an 8xx series stir-
rer has been connected and the settings made under CON-
FIG/peripheral units then the stirring rate can also be selected:
stirring rate 1...5...15
If you want your measurement to be made without stirring but still want
to stir the solution before the measurement then you should select the
control setting. In this way you can trigger a stirring sequence before
the start of each measurement with <MEAS/PRINT>:
prestir pause 0...99999 s
stir time 0...99999 s
poststir pause 0...99999 s