Chapter 7 – Maintenance
TestEquity TEC1 Thermoelectric Temperature Chamber
Page 7-3
How to verify the calibration
!
CAUTION:
TestEquity does not recommend performing the controller calibration
procedures unless you have verified that the controller is actually out of
calibration.
TestEquity recommends verifying the calibration before attempting to actually perform a
calibration. The microprocessor-based instrumentation used in TestEquity chambers seldom goes
out of calibration. If you try to calibrate the instrumentation before determining that calibration is
necessary, you may make it worse if done incorrectly.
Variations in temperature throughout the chamber interior are NOT a measurement of controller
accuracy. These variations, called “gradients”, are a function of the physical design of the
chamber and its airflow, the characteristics of the test sample, and how it is oriented in the
chamber. You cannot “calibrate” to improve gradients. The correct way to adjust what the
temperature controller “displays” compared to what is measured at some point other than the
controller’s sensor, is with the “Calibration Offset” parameter. See page 28 and 29 of the “EZ-
Zone PM User’s Manual” for details.
Total chamber accuracy, including the effects of controller accuracy, sensor accuracy, and
gradients is ±2.0°C. This is the indication on temperature controller compared to measurement in
the center of the chamber, in the range of +15°C to +55°C, after 30 minute stabilization at set
point. Actual measurements may typically be the following:
Controller
Standard
Error
55.0°C
53.5°C
-1.5°C
37.0°C
36.0°C
-1.0°C
23.0°C
23.1°C
+0.1°C
15.0°C
15.5°C
+0.5°C
These would be considered as being within the specification limit of ±2.0°C.
TestEquity typically enters a Calibration Offset value of -0.5°C to -1.5°C in order to achieve the
results above.
If calibration of the temperature controller is necessary, refer to page 56 of the “EZ-Zone PM
User’s Manual” and follow the instructions for RTD Input.
