Knick Stratos Multi E401N - Temperature Compensation of Process Medium

Stratos Multi E401N
69
Note: If Sensoface is enabled, a neutral smiley is displayed once 80% of the interval has expired. Once
the entire interval has expired, a sad smiley is shown, a maintenance required message is generated,
and the corresponding NAMUR icon is displayed. If the current outputs are configured accordingly,
a 22-mA error signal is generated.
Adaptive calibration timer: The time until the next calibration is automatically shortened depending
on the temperature and pH value.
Old sensor = timer expires faster.
The following measuring conditions shorten the adaptive calibration timer interval:
• Temperatures above 30°C/86°F
• pH ranges below pH2 or above pH12
The message test is displayed in the Diagnostics menu:
Diagnostics

Message List
The calibration timer is reset after each calibration.
Settings can be changed in the Cal Presettings submenu:
Parameter Setting

[I] [II] [Sensor]

Cal Presettings
5.7.3 Temperature Compensation of Process Medium
Note: If temperature compensation of the process medium is enabled, “TC” is shown on the display in
measuring mode.
Note: Function check (HOLD) is active. The current output and relay contacts behave in accordance
with the parameter settings. Return to measuring mode to exit the function check, e.g., with the right
softkey: Back to Meas.
The following are available for temperature compensation:
• Linear with input of a temperature coefficient TC
• Ultrapure water
• Table
Linear Temperature Compensation of Process Medium
If the medium’s pH value changes in linear fashion with the temperature, the temperature coefficient
TC can be determined for temperature compensation in %/K as follows:
TC = (pH
25
– pH
T
) · 100 / (25°C – T) [%/K]
TC Temperature coefficient [%/K]
pH
25
pH value at 25°C
pH
T
pH value at measuring temperature T
T Measuring temperature [°C]