The Centers for Disease Control and Prevention (CDC) January 2020 guidelines states that “Calibration testing should be done every one to two years or according to the manufacturer’s suggested timeline. TMDs can experience a “drift” over time, affecting their accuracy. This testing ensures the accuracy of the device continues to conform to nationally-accepted standards.”
The Primex OneVue Sense temperature monitoring solution is inherently stable. Our sensors are solid-state devices and do not require validation procedures. Our probes are Platinum Resistance Thermometers (RTDs) that have a long shelf life. The operational use period starts when a probe is plugged into and powered from the sensor control unit.
As such, we advise customers to base probe replacement or recertification every two years from the “first use date” rather than “last testing date” per our manufacturer’s recommendations (see supporting data section).
The CDC recommends a current and valid Certificate of Calibration Testing. The Certificate of Calibration Testing or Report of Calibration is to be issued by an appropriate entity and the certificate is to indicate one or more of the following items about calibration testing.
Conforms to International Organization for Standardization (ISO)/International Electrotechnical Commission (IEC) 17025 international standards for calibration testing and traceability
Performed by a laboratory accredited by International Laboratory Accreditation Cooperation (ILAC) Mutual Recognition Arrangement (MRA) signatory body
Traceable to the standards maintained by the National Institute of Standards and Technology (NIST)
Meets specifications and testing requirements for the American Society for Testing and Materials (ASTM) Standard E2877 Tolerance Class F or higher
Refers to another acceptable accuracy validation method, such as comparison to other traceable reference standards or tests at thermometric fixed points
Primex's probe manufacturer provides a certificate of traceability for each probe that meets one or more of the above calibration testing requirements, along with the following additional certificate requirements.
Model/device name or number
Date of calibration (report or issue date)
Confirmation that the instrument passed testing (or instrument is in tolerance)
Recommended uncertainty of +/-0.5° C (+/-1° F) or less
The following provides an example of a Primex Temperature Probe certificate. The certificate manufacturer will vary by the date purchased from Primex.
Probes purchased prior to November 2020 were manufactured by Automation Concepts, Inc.
Probes purchased after November 2020 are manufactured by TEWA Temperature Sensors.
TEWA certificates supplied in late 2020 may not have included the NIST traceability and acceptable validation method statement. This statement applies to all probes supplied by TEWA. Supplemental material that provides direct traceability is available upon request.
Data supporting Primex' stance regarding probe storage effect on the calibration period is provided in the graph below.
The graph details the amount of drift (or potential error) introduced by the probe sensing element when stored at room temperature. Based on the data, the amount of measurement drift expected when stored at or near room temperature is negligible. As shown in the graph, even after 3+ years of storage the typical drift is 0.002273°C and essentially a non-factor when compared to other tolerances within the measurement system.
Potential drift (measurement error) is negligible when storing probes at room temperature. When stored at or near room temperature, non-operational temperature probes do not vary from the documented results of the probe’s NIST certification report. The re-certification (calibration) period does not start until the probe is put into service and powered from the sensor control unit.