how the heck do you 'synchronize' thermometers?

[edprush]

I want to check the temperature of my refrigerator and none of the 4 thermometers I have show the same temperature.

 

[thescreensavers]

aa u cant. How the hell would you inless they were digital and why do you hve 4 thermomerters in ur refrig. if they cheap ones then that what you paid for.

 

[blue1friday2]

Is there a reason you need to know the exact temp of your fridge? I mean they are all within a degree or two right?

 

[MrBond]

You can calibrate your thermometers, but it's a difficult process. You need several solutions of known temperatures that fall within the range of your thermometer. You mark the actual reading on the therometer with the actual temperature (ie: liquid is 65°C, thermometer reads 70°C) and that's a point on your graph. You repeat this for at least 3 points (4+ is better) and get a calibration curve, which you can then use to tell the real temperature of your freezer.

Like I said, the process sucks, but that's how you calibrate them. It's not usually something the average person can do unless you have access to at least one known-accurate therometer that you can check your standard solutions with.

 

[MagnusTheBrewer]

You can calibrate kitchen thermometers (sometimes known as Bi-Therms) easily. Fill a glass with ice and water, insert thermometer, wait a minute and, rotate dial using a pliers to point to 0 celsius or 32 F. You should not use glass thermometers in your fridge anyways and kitchen thermometers are a couple of bucks apiece. Recalibrate once a month or so.

 

[BooGiMaN]

first you teach those little buggers to swim.....

 

[VTHodge]

Originally posted by: BooGiMaN
first you teach those little buggers to swim.....

10/10

 

[DrPizza]

Originally posted by: MrBond
You can calibrate your thermometers, but it's a difficult process. You need several solutions of known temperatures that fall within the range of your thermometer. You mark the actual reading on the therometer with the actual temperature (ie: liquid is 65°C, thermometer reads 70°C) and that's a point on your graph. You repeat this for at least 3 points (4+ is better) and get a calibration curve, which you can then use to tell the real temperature of your freezer.

Like I said, the process sucks, but that's how you calibrate them. It's not usually something the average person can do unless you have access to at least one known-accurate therometer that you can check your standard solutions with.

:roll:

Yes, it's easy to do.
Get some ice water. It's 32 degrees (F). Compare to the temperature on your thermometers. Add or subtract the necessary number of degrees.

Since you're working with refrigerator temperatures, the fact that the thermometers might not go up exactly 1 degree on their markings every time the actual temperature goes up one degree is most likely insignificant. i.e. if the thermometers actually go up 20 degrees when the actual temperature goes up 21 degrees or 19 degree, it's only going to mean about a 1/2 degree difference.

For best results, use distilled water when making your ice, and use distilled water for the ice water. If you have a physical constants book at your disposal, you can correct for your altitude/atmospheric pressure, etc. But, again, that's pretty much insignificant for your purposes.

 

[edprush]

Originally posted by: MrBond


It's not usually something the average person can do unless you have access to at least one known-accurate therometer that you can check your standard solutions with.

How the heck do you find an accurate thermometer? Just because one costs $90 doesn't mean it's any more accurate than a $20 one.

I don't think anyone knows the real temperature.

 

[Babbles]

Originally posted by: edprush

Originally posted by: MrBond


It's not usually something the average person can do unless you have access to at least one known-accurate therometer that you can check your standard solutions with.

How the heck do you find an accurate thermometer? Just because one costs $90 doesn't mean it's any more accurate than a $20 one.

I don't think anyone knows the real temperature.

Usually they are more accurate and precise. The 'better' thermometers may read something like ±0.5º and the cheaper ones may read ±2º - or something of that nature.
However for a refrigerator temperature, why do you care if it is accurate more than ±3º or so? Seems as if you are trying to overly complicate something.

 

[edprush]

Originally posted by: Babbleswhy do you care if it is accurate more than ±3º or so? Seems as if you are trying to overly complicate something.

Because 3º± makes a significant difference for perishable food particularly in the 37º range. Milk will spoil quickly at 40º and 33º can be too cold for some fruits.

 

[Eeezee]

Actually, you're right, no one 100% knows the real temperature because there is always some small measurable uncertainty with all emasurements.

Put one thermometer in ice water, take measurement, put it in fridge, take measurement. If it measures the ice water at 3 C, then subtract 3 C from the fridge measurement. That's your temperature in the fridge to within +- 0.5 degrees (at worst).

 

[QED]

There's nothing wrong with any of your thermometers.

The reason they do not agree with each other is due to global warming.

One thermometer says your fridge is warmer than it should be because there is a buildup of greenhouse gases in your fridge, which trap the suns deadly heat and UV rays.

Another thermometer says your fridge is colder than it should be because the melting of the ice coils in your freezer has shifted the flow of relatively warm, dry air from the vegetable bin away from the shelves where you keep your milk and OJ.

Another thermometer says your fridge is at the temperature it should be, and any variations in temperature are just a part of the fridge's natural warming and cooling cycles. However, we all know that this thermometer is just a right-wing fundamentalist kook and is ignoring decades of established scientic research claiming otherwise.

 

[Howard]

haha

 

[dullard]

Originally posted by: DrPizza
Yes, it's easy to do.
Get some ice water. It's 32 degrees (F). Compare to the temperature on your thermometers. Add or subtract the necessary number of degrees.

Since you're working with refrigerator temperatures, the fact that the thermometers might not go up exactly 1 degree on their markings every time the actual temperature goes up one degree is most likely insignificant. i.e. if the thermometers actually go up 20 degrees when the actual temperature goes up 21 degrees or 19 degree, it's only going to mean about a 1/2 degree difference.

For best results, use distilled water when making your ice, and use distilled water for the ice water. If you have a physical constants book at your disposal, you can correct for your altitude/atmospheric pressure, etc. But, again, that's pretty much insignificant for your purposes.

Listen to DrPizza. Make a batch of ice/water. Make certain there is about equal portions of ice and water, and that there aren't big pockets of just water or just ice. Stir it and wait a few minutes for it to reach ~32°F (forgetting to wait would be the biggest source of error). Then put in each thermometer. Again wait for them all to settle and give consistant readings. Then you'll know how far off each thermometer is. Add or subtract the error from each other.

You should get large temperature differences throughout your refrigerator. Where the air comes in from the compressor will be the coldest. On the top of the door is usually the hottest (ie where you should put butter or other dairy that you want to melt easier but don't want to spoil at room temp and where you should never put eggs even though there are often egg spots). The magnitude of the difference depends on fridge type, size, and how full you fill it.

 

[edprush]

Originally posted by: dullard Then put in each thermometer. Again wait for them all to settle and give consistant readings. Then you'll know how far off each thermometer is. Add or subtract the error from each other.

That was very good information about the various locations in the refrigerator differing in temperature. Thanks.

But on another note, just because the temperature is 3º off at 32º doesn't mean it is 3º off at 100º...especially with those coil thermometers.

 

[MrBond]

Originally posted by: edprush

Originally posted by: dullard Then put in each thermometer. Again wait for them all to settle and give consistant readings. Then you'll know how far off each thermometer is. Add or subtract the error from each other.

That was very good information about the various locations in the refrigerator differing in temperature. Thanks.

But on another note, just because the temperature is 3º off at 32º doesn't mean it is 3º off at 100º...especially with those coil thermometers.

That's why you might have to do it at several points like I suggested earlier. That's really not nessecary for the average person, but it can be done for highly sensitive cases. Since you're not in need of super-accurate results, you can probably get away with using ice and boiling water, remembering that water boils at 212F only at sea level and correcting accordingly. As long as the therometer varies linearly, you'll be fine with two points.

The food service industry calibrates at either the ice point or the boiling point for their thermometers. Ice point is supposed to be accurate within 0.1 degree F, boiling point is within 1 degree F.

If you want a really accurate thermometer, Omega sells a bunch of them, but they're going to be overkill for what you want. They also sell stuff to calibrate therometers, like constant temperature baths, but most of them are way out of the budget of the average person trying to find the temperature of their refridgerator

 

[Syringer]

Take the average of all of them.