Reference Thermometers

HI Everyone, 

I'm trying to revamp my companies thermometer calibration procedures and have some questions about acceptable reference thermometers.

We are currently using 2 Atkins cooper thermocouples with attachment probes.

They are verifying their calibration of these thermometers against each other in an ice bath. 

They are both NIST thermometers that are sent out annually for calibration. We verify the probes internally.

We use these thermometers to monitor our CCP temperatures. 

The way they are calibrating the thermometers against one another is not acceptable to me. They would also need a NIST certified Reference thermometer as well right? This thermometer would only be used for reference and nothing else and then we would be able to calibrate the two Atkins devices against this?

I may be over thinking the process, but i've always used a reference thermometer for reference and nothing else.

Thanks

WEebus

Yup ... reference thermometers are for checking working thermometers against and nothing else. Get the reference calibrated and certificated.

Hi WEebus,

I believe you have intuited exactly right; temperature devices used for monitoring and verification activities of HACCP CCP need to be NIST traceable and calibration checked according to the manufacturer's instructions. I have always found that the major vendors of lab-quality temperature devices have solid documentation with "how to" instructions for checking calibration at ice-point, calibration steps (when it is an applicable feature), certificates of tracability, recommendations of min. frequency of calibration check and instruction concerning how to send temperature unit out for factory re-certification.  The manufacturer's instructions should rightly be part of the supporting documentation of your HACCP plan. The reference device used to check all the other devices must be reference-grade and kept certified according to manufacturer's instructions. Of course the details of your HACCP plan must be followed as they were determined by the hazard analysis; the details of your HACCP plan must jibe with respect to the documentation corresponding to the temperature devices you use. As with any change in your products, ingredients, processes and flows, changes regarding the temperature devices mandate that you properly update the HACCP plan to reflect the devices. Also, since the devices are crucial to monitoring and verification of CCP's you should have a back-up plan to address fresh batteries for the units and the eventuality of breakage, malfunction, theft and when you send units out for manufacturer re-certification.

Regards,

Xylough

Dear Weebus,

What temperature do the thermometers  indicate in melting ice bath / validated SOP.?

If it's 0.0 degC and you are using them to check iced raw materials, probably nothing to worry about. Just do annual, external  calibrations.

Rgds / Charles.C

WEwbus,

With the Atkins models with plug-in interchangeable probes, I have been given to understand from the Atkins people that a factory calibration/re-certification is based on the specific probe used in the procedure. If and when you interchange a probe, you change the calibration to some extent. For the purposes of HACCP and CCP monitoring you should always use the same probe used for the calibration. If you use the same device with a different probe type for non-CCP purposes it should make no difference.