How to calibrate a thermometer?.

Flowki

Flowki

Well-Known Member
I can't seem to find any info at all on calibrating the type of digital thermometers we use.

My only thought process is getting something like a meat thermometer, calibrating that with the ice/boiling water methods and then using that as a base line in a sealed box alongside the other thermometers, but I tend to wonder if the meat therm will be too accurate for the standard ones we use. Maybe using a mercury thermometer in the same method would be better.

Anybody with a more simple idea, really welcome.
 
hotrodharley

hotrodharley

Well-Known Member
A mercury or alcohol mix thermometer would be the most reliable for reference. I’ve never heard of calibrating cheap digital thermometers.
 
Wizzlebiz

Wizzlebiz

Well-Known Member
how old is your fridge?

If fairly new it might have a temp control setting in degrees.

For example I can adjust my fridge from 35 degrees Fahrenheit to 50 something.

If that is the case for your fridge set it and maybe use that as your base line.

If not look up your fridge and see what the factory temp is.
 
Flowki

Flowki

Well-Known Member
Wizzlebiz said:
how old is your fridge?

If fairly new it might have a temp control setting in degrees.

For example I can adjust my fridge from 35 degrees Fahrenheit to 50 something.

If that is the case for your fridge set it and maybe use that as your base line.

If not look up your fridge and see what the factory temp is.
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Yes but the issue is how do you know the fridge is accurate compared to factory. It's also a low temp point spot check, the thermometers could be calibrated on that level but it doesn't mean they will be accurate at 70-85f.
 
Wizzlebiz

Wizzlebiz

Well-Known Member
Flowki said:
Yes but the issue is how do you know the fridge is accurate compared to factory. It's also a low temp point spot check, the thermometers could be calibrated on that level but it doesn't mean they will be accurate at 70-85f.
Click to expand...
That's fair. Just a of the cuff thought but yea you are correct.
 
Flowki

Flowki

Well-Known Member
hotrodharley said:
A mercury or alcohol mix thermometer would be the most reliable for reference. I’ve never heard of calibrating cheap digital thermometers.
Click to expand...
So putting a mercury or alcohol therm in a sealed box with the rest would be the most accurate bench mark?. I want to bring the temp of the box toward the warmer end so that the spot check is in range of the temps the therms will be used in.

They are therm/humidity and hygrometers, some ink bird, some the most reliable cheaper ones I could get (according to people who had compared them) while they also have calibration function. I don't want to continually buy new as I don't trust the shit you get on amazon/ebay, the quality of most items is rapidly declining. I'd rather stick with what I have and get some consistency instead of trusting this shit out the box. Even the middle range hygrometers are not immune to this shoddy quality and inaccuracy either. In the end a £15 hygrometer had way more positive comments on tested humidity accuracy than a £50 cigar one.
 
hotrodharley

hotrodharley

Well-Known Member
Flowki said:
So putting a mercury or alcohol therm in a sealed box with the rest would be the most accurate bench mark?. I want to bring the temp of the box toward the warmer end so that the spot check is in range of the temps the therms will be used in.

They are therm/humidity and hygrometers, some ink bird, some the most relaible cheaper ones I could get (according to people who had compared them). I don't want to continually buy new as I don't trust the shit you get on amazon/ebay, the quality of most items is rapidly declining. I'd rather stick with what I have and get some consistency instead of trusting this shit out the box. Even the middle range hygrometers are not immune to this shoddy quality and inaccuracy either. In the end a £15 hygrometer had way more positive comments on tested humidity accuracy than a £50 cigar one.
Click to expand...
Mercury manometer and thermometers are what we use in medicine for calibration of digital thermometers and blood pressure cuffs.
 
MICHI-CAN

MICHI-CAN

Well-Known Member
Flowki said:
I can't seem to find any info at all on calibrating the type of digital thermometers we use.

My only thought process is getting something like a meat thermometer, calibrating that with the ice/boiling water methods and then using that as a base line in a sealed box alongside the other thermometers, but I tend to wonder if the meat therm will be too accurate for the standard ones we use. Maybe using a mercury thermometer in the same method would be better.

Anybody with a more simple idea, really welcome.
Click to expand...
Old school mechanical. 1970's model is still accurate as compared to my digitals and fan control thermostats. In the bottom of pic. Just use 2 of different brands. All I got. Never worried about temps that much. Just cooling. 002.jpg
 
Flowki

Flowki

Well-Known Member
MICHI-CAN said:
Old school mechanical. 1970's model is still accurate as compared to my digitals and fan control thermostats. In the bottom of pic. Just use 2 of different brands. All I got. Never worried about temps that much. Just cooling.
Click to expand...
Yeah I need something that is a long term reliable bench mark. I don't mind paying the price for 1 decent thermo that can calibrate others for the foreseeable future.
 
MICHI-CAN

MICHI-CAN

Well-Known Member
Flowki said:
Yeah I need something that is a long term reliable bench mark. I don't mind paying the price for 1 decent thermo that can calibrate others for the foreseeable future.
Click to expand...
I'd suggest a graduated mercury tube. Still lab standard for a reason.
 
P

pete_pumpkin

Member
yeah I'd use one of those glass medical thermometers. I think the chemist sells them. You'd expect them to be a really accurate reference around the 40oC
 
printer

printer

Well-Known Member
Your first idea of using a meat thermometer and calibrate with the ice/boiling water method and using it as a reference would be my way to go. I bought a couple of meat probe thermometers and they seemed pretty accurate. But back to calibrating other thermometers using your reference, I would slap together a wooden box with a door and a hole to stick the reference probe through, seal the hole. Stick the thermometers in an wait. After a length of time (Depending how accurate you want it and your setup) take the readings and compare.

We used to have our students do labs calibrating with the boiling water/ice point method. On using the transfer method for the others using your 'reference' thermometer, I did many hundreds of calibrations this way.
 
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