Acceptable Temperature Tolerance Range at LN2 Temps

[rod65]

We are looking into setting a wider temperature tolerance range for the QC of our liquid nitrogen temperature measuring devices. We use a couple of different types of devices, some of our models utilize probes that connect to a thermometer or a datalogging device, and in these types, I understand the tolerance of the device and of the attached probes compound; one has to be added to the other to get the true acceptable tolerance. We use the liquid phase of Liquid Nitrogen to create a stable environment at -196 C. We frequently struggle to meet +/- 2 degrees Celsius, much less the +/- 1 degree tolerance used for the higher temps.

Is anyone out there using a temperature tolerance range wider than +/- 2 degrees Celsius for ultra cold temperatures? Are there any literature references that substantiate the establishment of the wider range?

[Lcsmrz]

The uncertainty of measuring devices at that temperature is quite high, so trying to meet +/- 2 C will be quite a chore.

There is no regulatory requirement for a tighter range for LN2, other than doing temperature mapping when validating.

We set rather wide ranges for freezers for normal use, as long as the temp is well within the storage temp, then tighten them under more standard conditions when cross-calbirating sensors.