Calibration and Instrumentation Services perform onsite calibration of temperature measuring instruments in Coolrooms, Refrigerators, Freezers, Ovens and Incubators for those who chill, freeze or heat produce or require a temperature controlled environment and who need to know the installed measuring equipment is operating inside specifications/tolerances.
Potential benefits, in addition to complying with QA requirements, include reduced risk of losses due to produce not being chilled/heated correctly and reduced energy costs where over-chilling/heating is occurring.
In such applications the temperature sensors are commonly resistance temperature devices, such as Platinum Resistance Thermometers (PRTs). Such instruments can be susceptible to damage that may cause offsets rather than complete failure. Deficiencies in wiring/joints can also lead to errors. Various procedures may be used to test such systems, such as one of the following:
- Disconnect the sensor and apply a known reference signal to the indicator/controller and compare it with the Reference.
- Position a calibrated Reference sensor next to the sensor being tested.
- Test the sensor and indicator against a Reference, over 3 or more temperatures, using a wet-well temperature bath.
- Map temperatures throughout the enclosure. CIS can monitor and log up to 34 points, provide an analysis of the data, highlight hot/cold spots, etc.
It is relevant to note that Calibration and Instrumentation Services’ portable equipment is temperature compensated to operate accurately over a very wide range of environmental temperatures, with very small temperature coefficients applicable outside the compensated range. Much alternative calibration equipment lacks such compensation.