Lake Shore Model 218 Temperature Monitor User’s Manual
5-8
Special Features
5.2.4 SoftCal
™
Accuracy with Platinum Sensors
NOTE:
A SoftCal™ calibration is only as good as the accuracy of the calibration points. The
accuracies listed for SoftCal™ assume ±0.05 K for 77.35 K (liquid nitrogen) and 305 K (room
temperature) points. Users performing a SoftCal™ with Lake Shore instrumentation should
note that liquefied nitrogen and ice point temperatures can vary as much as ±0.5 K. Use a
calibrated standard sensor if possible.
One-point SoftCal™ calibrations with platinum sensors have no specified accuracy.
Two-point SoftCal™ calibrations for applications above 70 K are performed at liquid nitrogen
(77.35 K) and room temperature (305 K). Accuracy for the PT-102, PT-103, or PT-111 platinum
sensor is:
±250 mK from 70 K to 325 K
≈
±500 mK from 325 K to
≈
±1400 mK at 480 K (DIN Class A or Class B tolerance)
Three-point SoftCal™ calibrations are performed at liquid nitrogen (77.35 K), room temperature (305
K), and high temperature (480 K). Accuracy for the PT-102, PT-103, or PT-111 platinum sensor is:
±250 mK from 70 K to 325 K
±250 mK from 325 K to 480 K.
5.2.5 SoftCal™ Calibration Curve Creation
Obtain calibration data points. Press
SoftCal
. The
display to the right appears. Use the Data
Selection keys to cycle through the curves to use
as a basis for calibration. Press
Enter
when the
desired curve appears.
The second display in the setting sequence
appears. Use the Data Selection keys to cycle
through the inputs where the new SoftCal™ curve
stores. Press
Enter
when the desired input
appears.
CAUTION:
If a user curve already exists at the
input location, the instrument overwrites it with the
new SoftCal™ user curve.
The third display in the setting sequence appears.
Use the number keys to input up to a ten-digit
serial number, then press
Enter
.
The fourth display in the setting sequence
appears. Use the number keys to input the voltage
or resistance of the first calibration data point, then
press
Enter
. Use the number keys to input the
temperature in Kelvin that corresponds to the
voltage or resistance of the first calibration data
point, then press
Enter
. Points outside acceptable
range will not be allowed. If the first point is not
used, press
Enter
twice without entering any data.
The fifth display in the setting sequence appears.
Use the number keys to input the voltage or
resistance of the second calibration data point,
then press
Enter
. Use the number keys to input
the temperature in Kelvin that corresponds to the
voltage or resistance of the second calibration
data point, then press
Enter
. If the second point is
not used, press
Enter
twice without entering any
data.
