Does anyone know of a standard, reference, etc. that says how close a thermometer must match to its counter part?  We have a thermaviewer that logs the temperatures, the refrigerator's temp probe and thermometers on top and bottom shelfs of fridges.  I have two different sources, one saying they must match within 1 °C and the other within 2 °C.  Help!!....................

For storage devices, they all have to be within the appropriate storage temperature for the device however the differences between them is not important.  For refrigerated storage between 1-6 C, one could be at 1C and another at 6C and it would be acceptable.  What references were provided by your sources?

As for us here in the US, we have to have documentation (once a day) to be able to prove that everything is close enough to the NIST thermometers to warrent using the alarms and recorder (hooked up to electronic probes) as safe guards.  (Otherwise I think we would have to manually log the thermometer temps every four hours to show that the refrigerators and freezers are always within the acceptable range).

 

So how close the electronic monitor temps are to the NIST thermometers IS important.  For example, an acceptable range for a refrigerator in BB may be 1-6 C. If you have an alarm set to go off if the temp falls below 1.5 C or above 5.5 C, you need to be able to show documentation that the reading from that probe is within 0.5 degrees of the NIST thermometer.  Say it is off by -2 C: that means when the probe that controls the alarm reads 2, the fridge temp is actually at 0 C! Not a good situation.

 

Here we make sure that all of the fridge temp readings are all within 1 C of each other, and that the freezer temps are within 2 C.  The alarm cut-offs are set to accomidate that variance.

 

Scott

We compare all thermometers/probes to NIST once a year and they should agree +/- 1 C.   Once in the fridge (or other equipment), there is no requirement that they must all agree to others within +/- X degrees.  

 

To synderci - you can probably get rid of your top and bottom bottle thermometers if your fridge probe compares favorably to NIST.

I have always used ref thermomters +/- 1C with each other and freezers: +/- 2C.  I compare 2x/yr with NIST calbrated - same criteria.