Infared Thermometers

I just tried a little experiment. I filled a carboy with warm water and let it sit for about 20 minutes. Then I stirred the water and used a very accurate probe to measure the temperature. It was 90.8F. Then I held my IR thermomenter (also quite accurate) right up against the neck of the fermenter and aimed it inside. The temperature read 89.6 F, about a degree lower. The theoretical focal point was likely somewhere below the bottom of the fermenter. I also tried aiming it by holding it higher, but the readings jumped all over since the light was bouncing and reflecting everywhere near the surface and inside neck of the carboy.

Then I measured the outside of the carboy with the IR thermometer. I got a reading of 87.4 F near the top, and a reading of 87.2 near the middle. As expected, the outside temperature of the carboy was a couple of degrees cooler than the inside.

Just a Note: uUsing the IR thermometer, the readings change a little as you change the angle or distance from the surface.

 

OldBrewer, thanks for the data! I'll follow-up one of these days if I ever remember.

If I can turn off the decimal point on my IR, I'll do that. To be very frank (it's the scientist in me), I don't give a F about decimals. If I can do that then the temp won't vary so much depending on how I aim it.

 

Yup, there is a difference between precision and accuracy.

Cheers!

 

Precisely! *smirk*

 

to add to your note: Depending on the specifications of the IR thermometer, changing the distance may greatly change the diameter of the IR light that it is aggregating the temperature within. More expensive IR thermometers have a smaller diameter at further distances away. Some I think are still about 1'' even at 30'.

 

Mine is a 1 inch spot at 30 inches (focal point). After that, the spot increases in diameter.

 

I'm almost afraid to ask, but why did your wife buy an infrared thermometer?

 

Perhaps. The one I got was likely defective. As I said, I got a full refund. As I also said, +/-20 is fine for pancakes! I'll probably buy another someday, but it's not high on my 'gotta have' list (a disturbingly short list).

For 'real' temp measurements, the Thermapen can't be beat! I calibrate my $10 probe thermometer with it every brew day. But it really shines in the kitchen and, even more so, on the grill. My perceived culinary skills got a major boost when I got that. But it doesn't replace a good infrared thermometer. I just don't have a pressing need for that today.

 

I have a digital probe and an infrared for cooking. The probe is priceless as it can come up to temp in less than 5 seconds, the infrared is good for checking a pan when searing (and my grill outside), and also checking the temp in the fridge when shit seems to be going wrong. I would never trust it for brewing. It hits the surface (as people have mentioned above) and that is about it. Granted it is cool as shit to run around the house and temp everything, but other than that, it is what it is. The great thing about it is if you ever are trying to diagnose an overheating issue with your car, it can come in handy checking the various parts on the car.

 

So, it sounds like it would be a useful-ish tool for making sure a starter is in the correct range (not too hot, not too cold) but not much more? That was the only reason I considered buying one as everything else has a thermowell and temp control.

 

Yes if you make the assumption that your fluid is at a constant temp throughout and your vessel is a good conductor of heat then it would be good for that. I used it to adjust my beer fridge when I got it, I would shoot it around in side and on the sides of bottles to find out where the hot/cold spots were. Then whenever I am cooking and I grab a beer out of the fridge I will sometimes shoot the side of the bottle and then drop the prob into the bottle, and they were usually pretty spot on.
Edit: Here is the model I have Taylor 9306N. I highly recommend it, have had it for several years, 1 battery change

 

We are using several infrared thermometers to monitor the temperature of leaves in tree canopies. Very useful to our purpose for reasons that I believe illustrate when these are useful over probes:
1. The leaves are out of reach.
2. The temperature gradient from leaf surface to leaf center is extremely narrow, leaves being flat and all, so surface temp is sufficient for the purpose.

Ultimately, colleagues will use the data to model leaf photosynthesis and respiration, which can be used to interpret real time measurements of net ecosystem carbon exchange. Pretty cool stuff. All of which I mention <ahem> as a useful analogy: you could also use them to monitor the surface temperature of glass of beer to model head retention and net beverage exchange of carbon dioxide.

Sorry, isn't this the thread about what you do when you are not thinking of beer?

 

It's also useful when the cat enters the room and you left the laser pointer in your other pants.

 

I just thought of an excellent use for my IR thermometer...... my son has a flu right now. Wish I would have thought of this last night when taking his temperature. I have a table showing nominal forehead temp (and other body parts) so this could prove very useful. The digital forehead therm that we bought 15 years ago is a POS, never worked right and takes about 30 tries before it spits out any numbers. The alternative glass thermometer is very accurate but isn't as easy and instantaneous as an IR, and kids hate sucking on the thing for 5 minutes. For moms and dads on the go, IR, baby.

 

@dmtaylor share that table, would be interested in that

 

Well sure, I can type it easy enough:

Forehead 98.0 F
Tongue 98.6 F
Anal 99.8 F
Ear Canal 99.4 F

There is also an age adjustment for these.

<2 Years Add 0.7 F
3-10 Years Add 0.3 F
11-65 Years Add 0
>65 Years Subtract 0.2 F