Themometer bottles in storage devices

[Mabel Adams]

I seem to remember reading here some time back that some places use the fridge readout for their internal thermometer and do not also have a thermometer inside the fridge that is checked every day. This seems logical to me. Since all we need is a NIST traceable temp that is recorded every day, we could easily check the readout agianst and NIST reference thermometer periodically and record the readout every day. Then we need to make sure the chart recorder reads accurately. If you are doing this have you had any issues with FDA or AABB inspectors? How often do you check the readout against the NIST reference? For storage units requiring top and bottom thermometers, one could be the readout and the other a bottle, right?

[John C. Staley]

Mable, I did that with a Helmer i Series freezer. It has a thermocouple on the top shelf and another on the bottom shelf with a digital readout on the front for both of them. I calibrated/validated both on receipt and again annually after that. We recorded the read outs on a daily basis just like the thermometers of old. It worked great and no inspectors had any issues with what I had done. I had planned on doing the same thing with the 2 i-Series refrigerators I had ordered prior to my timely dedparture.

[Franklyn]

All of our refrigerators with integrated thermometers are calibrated for this use rather than keeping bottle thermometers in them. Each of these units is on the list for annual recalibration and we can produce the records of the recalibration on demand. However, depending on the size of the refrigerator, you may need a top and bottom thermometer and not all refrigerators/freezers have them - so keep that is mind and consider the value of validating the single point reading for accuracy.

As for inspection problems, we haven't had any in almost a decade of doing it this way.

[AMcCord]

The manual with my new Helmer i-Series recommends a monthly check on display temp top and bottom. Doesn't take very long. (I will admit to also having bottles in my fridges:redface:. Old habits die hard.)

[Mabel Adams]

So how big does a fridge need to be before it requires 2 thermometers--top & bottom? Is it determined by the fridge manufacturer or some obscure reg or guidance that I can't find.

[LaraT23]

I have bottles inside my double door refrigerator because the probes that the unit comes with are only one side of the frig. That side can be checked using those probes in the bottles hooked to the chart recorder. The other side has nothing, so I use bottles for that. Hope that helps.

[Alternatives]

So how big does a fridge need to be before it requires 2 thermometers--top & bottom? Is it determined by the fridge manufacturer or some obscure reg or guidance that I can't find.

Good question! Something that is done in pharma industry and might be implemented in an hospital; As there are no regulations on the number of sensors to be placed into a equipment, solution is firstly to perform a mapping of your fridge or equipment in order to determine hot and cold spot. Under protocol, and regular business hours (with door opening), it will show you how homogen is the temperature inside your fridge. Pharma companies then select their hot and cold spot where temperature sensors will have to be placed (this is a requirement). So the number of probes will depend of disparity of temperature inside your equipment.

What do you think?

Benoît