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IR thermometer accuracy?

 
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Maxwar



Joined: 17 May 2008
Posts: 14
Location: Atlanta, GA 30309

PostPosted: Mon Aug 04, 2008 3:50 am    Post subject: IR thermometer accuracy? Reply with quote

What is the best way to check the accuracy of my IR thermometer (MasterKool). Does anyone have any experience with this brand?
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Michael Chu



Joined: 10 May 2005
Posts: 1617
Location: Austin, TX (USA)

PostPosted: Mon Aug 04, 2008 7:14 am    Post subject: Re: IR thermometer accuracy? Reply with quote

Maxwar wrote:
What is the best way to check the accuracy of my IR thermometer (MasterKool). Does anyone have any experience with this brand?

You can use an accurate probe thermometer and measure the surface temperature of something and then use the IR thermometer. If it's off, adjust the emissivity setting (if you have one) on the thermometer as different materials have different emissivity coefficients.
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Maxwar



Joined: 17 May 2008
Posts: 14
Location: Atlanta, GA 30309

PostPosted: Mon Aug 04, 2008 2:17 pm    Post subject: Reply with quote

What worries me is that I cannot get a correct reading on boiling water. Whereas my normal probe thermometer (CDN) gives a spot-on 212F, the IR gives a read well under.
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GaryProtein



Joined: 26 Oct 2005
Posts: 535

PostPosted: Mon Aug 04, 2008 10:52 pm    Post subject: Reply with quote

The IR thermometer may be reading too low because it is reading the temperature of the condensing steam above the boiling water, and not the boiling water itself. Try pre-heating your oven for a good "heat soaking" to about 250 or so, and leave a candy thermometer near the back wall of the oven. Then use the IR thermometer to read the temp of the back oven wall. See how it compares to the candy thermometer reading.

+++++

Michael: How critical is that adjustment if you AREN'T measuring the temperature of shiny polished metals.
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DrBiggles



Joined: 12 May 2005
Posts: 355
Location: Richmond, CA

PostPosted: Tue Aug 05, 2008 3:02 am    Post subject: Reply with quote

GaryProtein wrote:
The IR thermometer may be reading too low because it is reading the temperature of the condensing steam above the boiling water, and not the boiling water itself. Try pre-heating your oven for a good "heat soaking" to about 250 or so, and leave a candy thermometer near the back wall of the oven. Then use the IR thermometer to read the temp of the back oven wall. See how it compares to the candy thermometer reading.

+++++

Michael: How critical is that adjustment if you AREN'T measuring the temperature of shiny polished metals.


Does an IR thermometer read internal or surface temperature?
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Michael Chu



Joined: 10 May 2005
Posts: 1617
Location: Austin, TX (USA)

PostPosted: Tue Aug 05, 2008 9:30 am    Post subject: Reply with quote

GaryProtein wrote:
Michael: How critical is that adjustment if you AREN'T measuring the temperature of shiny polished metals.

Not an expert, but it seems like 0.95 emissivity provides accurate readings for most everything I've tried. I think many of the IR thermometers have it permanently fixed at that value...
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GaryProtein



Joined: 26 Oct 2005
Posts: 535

PostPosted: Wed Aug 06, 2008 5:51 am    Post subject: Reply with quote

DrBiggles wrote:

Does an IR thermometer read internal or surface temperature?


An IR thermometer measures the surface temperature of an object. If you want to know the internal temperature of a prime rib roast, you need an insertable probe.
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DrBiggles



Joined: 12 May 2005
Posts: 355
Location: Richmond, CA

PostPosted: Wed Aug 06, 2008 2:23 pm    Post subject: Reply with quote

GaryProtein wrote:
DrBiggles wrote:

Does an IR thermometer read internal or surface temperature?


An IR thermometer measures the surface temperature of an object. If you want to know the internal temperature of a prime rib roast, you need an insertable probe.


Well, that's what I was figurin'. Over the course of a few years I run in to people who purchased it thinking they'd be able to use it for internal temperature and only later realize it's the wrong tool for the job. Thought I was missing something.

Cheers
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IndyRob



Joined: 17 Dec 2006
Posts: 77

PostPosted: Fri Aug 08, 2008 10:51 pm    Post subject: Reply with quote

I do a lot of sous vide cooking which involves temps well under 212F. Just because there's a lot of waiting involved, I often pull out my IR thermometer and check the surface of the water against what my Thermapen tells me. It's usually with a couple of degrees F.

I've also found it somewhat accurate at measuring the progression of pasta water towards boiling. I've found that to be fairly accurate as well, but once a boil has been acheived, my mind has gone on to cooking so I've never measured beyond that (on water anyway, I rely on it's measurements on cast iron up to 780 degrees F).

From the instructions of my IR thermometer, there's a lot to keep in mind regarding the reflectivity of the surface you're trying to measure. It seems to get along with fat, but not so much with, say, chrome.
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