wtw pH 171 2K, Operating Manual

Page: 130 / 160

Calibration
134
Display after invalid calibration
If after an invalid calibration the calibration mode is left an error is displayed and instead of the
measured value 3 lines are indicated.
The last measured value remains frozen.
Error indication in calibration mode
Example:
No stable buffer value achieved.
(After 10 minutes of measuring without achieving a
stable value).
With
return to start of calibration.
Invalid slope or inadmissible offset voltage
("Asymmetry" ASY).
(Values outside the admissible ranges of:
Slope -50 ... -62 mV/pH
ASY -45 mV ... +45 mV)
With
return to start of calibration.
Error indication in measuring mode
Example 1 channel instrument:
This message is only displayed with AutoCal TEC.
There is an unvalid calibration; the key in the
display flashes until the error is accepted by
pressing the
key.
The pH value is not displayed; the temperature is
displayed. Then return to calibration with
Cal .
As soon as there is a valid calibration the pH value
is indicated again and the recorders and relays
follow the new measured value.