User's Manual

Chapter 10: Sensor Verification
Kaye ValProbe RT User Manual 89
Defining Verification Strategy and Criteria
The Kaye ValProbe RT software allows you to verify Logger accuracy at up to six set points.
Verifications can be used for multiple purposes. Kaye recommends a quarterly verification to
ensure the Loggers are still within their specification of 0.1°C, or based on you SOP’s or Risk
management assessment, perform a pre -Verification before your Qualification study and a
post Verification after the study to ensure Logger temperature are within your defined process
criteria.
In wired based systems utilizing thermocouples, it is common practice to run a Pre-Calibration
prior to the Qualification and a Post Verification afterwards. The Pre-Calibration is required to
compensate for the unknown error of the thermocouples and ensure that the loop
measurement is within calibrated deviation criteria.
With the ValProbe RT Loggers it is not necessary to do a Pre–Calibration of the logger as the
sensor and logger were already calibrated to within 0.1°C at the factory and any error for the
sensor is already compensated for in the factory calibration. Therefore, a Pre-Verification
should be performed prior to the Qualification to again ensure the Logger and sensors are
within defined deviation criteria. At the end of the Qualification a Post-Verification can be
performed to ensure the Loggers and sensors are still within defined criteria. (0.5°C)
Regulatory requirements while defining the need to ensure sensors used for Qualification
studies should be calibrated and then verified, do not set any frequency guidelines other than
at least once a year. The determination of whether to verify for every run or every day or once
a quarter or only send them back to the factory once a year should be defined by a risk
assessment or company SOP’s. Kaye’s recommendation is to run a verification against the
IRTD at least once a quarter along with a once a year factory calibration.
Selecting the Proper Calibration Bath - Uncertainty
When performing any sort of or verification it is important to understand the required criteria,
as well as the uncertainty of the Temperature Standard and Temperature Bath to ensure the
equipment has the necessary stability and uniformity to verify the accuracy of the Loggers.
When Kaye performs Factory calibration of the Loggers, we utilize a special IRTD and Oil bath
that provides a total uncertainty of < 0.28°C. This allows enough ratio to safely calibrate and
verify the accuracy of the Loggers to within specifications of 0.1°C.
If your verification strategy is to do a periodic check of the Kaye loggers to ensure they are
within Kaye specifications of 0.1°C then you need to utilize Temperature Baths and
References that have an adequate uncertainty to ensure valid results.