Calibration of thermometers

Hi!
We have a couple of sensors in our freezers that we asked our freezer firm to calibrate.
Unfortunately we got a corrective action because they just wrote 'reads correctly' on the certificate.
They didn't write anything else 😔
If we have an externally calibrated thermometer, surely we can do the calibration ourselves?
Is it so simple that we take the thermometer and hold it in the air close to the sensor?
Compare the two readings?
Or?

What your proposing would be a verification, not calibration (which you should do just the same)

 

If you can remove the ones in the freezer, then you can make an ice slurry or use boiling water against your outside calibrated thermometer as calibration for the ones in the freezer

Thanks Scampi, we can't adjust the set point so correct, it isn't calibration.
Can we measure them 'in place'?
At the usual operating temperature? (-25)
I wouldn't do 100 as that is too far from the operating temperature, but could do ice slurry at if they can get removed...

If the built in thermometer is either non-removable or not able to be calibrated, you may need to consider implementing a monitoring procedure that can utilize a thermometer or probe you can calibrate.

If you can remove them and use an ice slurry along side your calibrated reference thermometer, AND they are accurate (+/- 1C) then that will suffice as calibration.  HOWEVER, if they are not within 1C, then you should replace them since you've said you cannot adjust them

Hi!
We have a couple of sensors in our freezers that we asked our freezer firm to calibrate.
Unfortunately we got a corrective action because they just wrote 'reads correctly' on the certificate.
They didn't write anything else
If we have an externally calibrated thermometer, surely we can do the calibration ourselves?
Is it so simple that we take the thermometer and hold it in the air close to the sensor?
Compare the two readings?
Or?

Hi AJL,

 

IMEX you can call it Calibration provided the 2nd thermometer is a "Master", Nist traceable, appropriately externally calibrated unit.

Have used this Procedure for Cold Room thermometers without ever getting an auditor criticism.

Great thanks Charles. I only just found out about how reasonable was to get an external calibration so we will be doing that from now on. 👍👍

Will end up being more cost effective than having the calibration (sensors)completed by the external service provided. 💪