Metrohm 781 pH/Ion Meter - Manual (Page 59)

5 Configuration
780/781 pH/Ion Meter, Manual
49
LCD off after 1,2...999 min, OFF
The display of the pH/Ion Meter has an illuminated background. In or-
der to increase the working life of the lamp you can switch off the dis-
play automatically when the instrument has not been used for a certain
time. Please note that, if the lamp is switched off and on too frequently
then its working life will also be reduced. This means that times of about
30 min can be recommended.
The fact that the LCD illumination is switched off does not affect the
functioning of the pH/Ion Meter in any way. It continues to work normal-
ly. The lamp can be activated again with any key except .
Please note that the key switches the instrument off. All
other keys only have the function of activating the LCD illumination. This
means, for example, that runs will not be terminated when the
key is used to reactivate the background illumination.
date YYYY-MM-DD
time hh:mm:ss
You can set the date and time here. The program will only accept num-
bers which make sense.
time zone 12 ASCII characters
For complete documentation you can add details of the time zone to
the time information for output in the report header. The input of up to
any 12 characters is possible. Examples: 'MEZ', 'UTC-05:00'
(Coordinated Universal Time minus 5 h) or location of the measurement.
temp.sensor: Pt1000, NTC
The 780/781 pH/Ion Meter supports the use of two different types of
temperature measuring techniques T: Pt1000 (platinum resistance
thermometer) and NTC ('Negative Temperature Coefficient' semicon-
ductor). This means that the configuration must be adapted according-
ly. If NTC sensors are used then it is also necessary to enter two sensor
characteristics; these can be found in the specification of the sensor:
R(25 °C) 10000...30000...100000
B value 1000...4100...9999
The standard values R(25 °C) = 30000 ohm and B value = 4100 K ap-
ply to the use of a Metrohm electrode with NTC sensor (e.g. 6.0228.010
LL Solitrode NTC), where the B value refers to 25 °C and 50 °C. B val-
ues of other NTC sensors are frequently based on different reference
temperatures (usually 25 °C / 50 °C – 100 °C). When entering your own
sensor characteristics the effect of the second reference temperature
on the measuring accuracy of an NTC sensor is negligible.