I work in a research lab and one of our most critical pieces of equipment is a large chest freezer that normally runs around minus-80-degrees Celsius. It is an older unit with audible alarms built in, but no in-built
monitoring capability. We'd like to install a simple means of detecting out-of-range temperature conditions and sending out a text message, etc., if the unit starts getting too warm. What's the best way to go about this?
Specifically, the thing we want must be able to:
(1) Detect and accurately sense temperatures in a range down to -80 degrees Celsius.
(2) "Sample" the temperature at least once every 5-10 minutes and check it against a user-determined limit value (-50 degrees C or thereabouts).
(3) Flag the condition if the limit value is reached and send a text message to at least one cellular phone number.
I have done a fair bit of searching for pre-fab temperature monitoring products, and there are certainly a bunch out there, but very few of them actually go down to -80 Celsius. Many stop at -50 C, which would be useless for this application. A simple power-monitoring device would also be insufficient, given that one possible failure mode of this freezer is a shutdown of one of the two compressors (which doesn't cause the unit to shut off entirely, but which would result in an unacceptable temperature rise).
Probably the closest thing to what I'm looking for is this thing
(used in conjunction with the available ultra low temperature sensor
...but since we don't actually need multiple inputs or the means to connect multiple types of sensor, that product is a tad over-featured.
Getting to the point, it seems like this is the sort of thing one ought to be able to do with a thermistor and an Arduino-type board (I have an OSEPP Uno here)*...is there any good reason why not?
And if not, can anyone recommend a specific thermistor and accessory board (for sending SMS alerts)?
* I'm a little embarrassed to admit that despite being an EE I've never actually used an Arduino board and I have no past experiences incorporating thermistors into designs, just because it's never come up until now. I'll recommend a pre-fab product if that turns out to be the best option for my employers, but I'd really prefer to take this as an opportunity to save them some money AND enhance my skillset.