Checking Infrared Gun Calibration?

[TheCountofQ]

Last night I did a pre burn on the new Ranger (w/ bacon included), and knowing the factory thermometer is typically inaccurate, I thought I would shoot the lid with my infrared to get a reference of where the HB thermometer points at various actual temps. Things didn't work out so well...

Essentially, my infrared showed temps in the 110 range, throughout the "cook", although the dial's needle pushed barely into the red zone (beginning at 400F). Mind you, I dumped a full chimney of lit coals into the firebox, which is a full firebox, and I'm certain temps were at least 400F.

So, I assume something is amiss with my infrared. That is unless it has to do with the shiny stainless affecting the readout.

So, what are my next steps to either correct for the reflectivity, or test the correct operation of the infrared?

Thanks in advance?

[MBMorgan]

Remember that the lid thermometer is measuring air temperature while the IR gun is measuring surface temperature ... which can be wildly different. (Unless I'm not understanding what your "HB" thermometer is and is doing)

[TheCountofQ]

Correct. Still, taking a thin (I imagine even a thick) piece of stainless and place it with +400 degree temps on one side, and +80F temps on the other, for hours) that stainless is gonna raise in temp a whole lot. I'm not saying it'll reach the actual 400, but it's gonna get closer than 110. The stainless was hot enough that touching it, even momentarily, was dangerous.

So I am certain this accounts for some of it, I doubt it tells the whole tale.

The infrared has been dropped a few times.... but still intact.

[EdF]

The other thing is that those infrareds are tuned to certain kinds of surfaces, and have to be adjusted (or accommodated for) when you hit a different kind. Thermoworks spells this out a bit. So your idea that it might be the stainless may just be your explanation.

[Jerod Broussard]

Blame it on the Chromium!!!!

[Willy]

Try taking the temp of something inside the grill cover, maybe the grill grate. Also shoot the ground or walls of your home to see if those temps are close to ambient. Try the inside of your kitchen oven and the inside of your fridge and freezer. I just put a pot of water to a boil and my IR gun showed 205°F, which is about right for my altitude. Try a piece of aluminum foil at room temp.

[TheCountofQ]

OK. I've got a couple of small cast iron pans seasoning in it right now. The dial gauge shows 400. The surface temp of the Hasty is showing 120ish, and the cast iron is 505 (currently directly over the coals) and the one over the unlit coals is at 450. It must be a reflectivity issue.

I guess I'll have to get the Stoker out to get the info I want.

Thanks all.

[MBMorgan]

Assuming your IT thermometer has adjustable emissivity (which is what I think you're referring to as reflectivity), here's a link to a table of emissivity coefficients of various materials (e.g., polished stainless steel at .85): http://www.engineeringtoolbox.com/em...nts-d_447.html

[Jerod Broussard]

Aha you see that low number behind Chromium?

[TheCountofQ]

Very, very interesting. Thank you!!