How to calibrate a thermometer?.

[Flowki]

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]

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

 

[Wizzlebiz]

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]

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.

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]

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.

That's fair. Just a of the cuff thought but yea you are correct.

 

[Flowki]

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

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.

 

[Flowki]

That's fair. Just a of the cuff thought but yea you are correct.

It's not that I want you to be wrong, I wish it was that simple, really.

 

[hotrodharley]

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.

Mercury manometer and thermometers are what we use in medicine for calibration of digital thermometers and blood pressure cuffs.

 

[MICHI-CAN]

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.

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.

 

[Flowki]

Mercury manometer and thermometers are what we use in medicine for calibration of digital thermometers and blood pressure cuffs.

Can you reccomend anything specific company wise?.

 

[Flowki]

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.

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.

 

[Wizzlebiz]

It's not that I want you to be wrong, I wish it was that simple, really.

Nah im with ya. Every idea cant be the best one. No worries.

 

[MICHI-CAN]

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.

I'd suggest a graduated mercury tube. Still lab standard for a reason.

 

[hotrodharley]

Can you reccomend anything specific company wise?.

https://www.labdepotinc.com/p-62536-mercury-thermometer?gclid=Cj0KCQjwhb36BRCfARIsAKcXh6GFLfuN4SRPaZ7XMZQsgTZiNI2WGpxYL4tk8BcsXm7ZCTrEUO1TJaMaAttOEALw_wcB

 

[rkymtnman]

somebody had to go here:
up the old poopshoot is 98.6F

 

[Renfro]

If the thermometer uses a waterproof probe you could use the ice point method.

 

[MICHI-CAN]

somebody had to go here:
up the old poopshoot is 98.6F

Nope. It's halfway between 98 and 100 graduations. Haven't seen mercury graduated that finely. Better be a set with serious magnifier. LOL.

 

[Flowki]

https://www.labdepotinc.com/p-62536-mercury-thermometer?gclid=Cj0KCQjwhb36BRCfARIsAKcXh6GFLfuN4SRPaZ7XMZQsgTZiNI2WGpxYL4tk8BcsXm7ZCTrEUO1TJaMaAttOEALw_wcB

Thnx

somebody had to go here:
up the old poopshoot is 98.6F

I would offer update pics as a joke but you might say yes

 

[pete_pumpkin]

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]

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.