Infrared Thermometer on Sale

[Darwin Maring]

It would be interesting to see what Snap-On has to say about the accuracy of their device. They are one of the manufactures of high end tools and test equipment.

Checking Aircraft engine temps. We would use a grease pencil (I sometimes thought that the Army runs on grease pencils and floor buffers).

Would use the grease pencil to check cylinder head temp to spot a bad spark plug. Real scientific stuff there. The quicker it melted, the hotter it was. Was looking for a cooler cylinder head and depending which mag we were running on we could determine which of the 2 plugs was bad.

Also had an electronic device that looked like an aluminum rod with a temp gauge on the end. Would clip a lead to metal then put the pointed end of the rod on the part we were measuring and would get a reading. Was to much of a pain to go and get so just used the grease pencil in our pocket.

[Byron Kinnaman]

OK, I thought I'd not say anything more about IR thermometers, but...

I checked Snap on's web site to see who was making their IR thermometers and look at their specifications. Results are;

This one is good. The specifications indicate it would work just fine for most trailer usage.

This one has issues. 1) Emissivity is adjustable, not for the average user. 2) Spot to distance ratio is so high that spot size is quite small, 30:1 30" away you get a 1" diameter spot. 3) High price.


The cheapest one has many issues. 1) recommended measuring distance is .5" to 2". 2) Spot distance ration 1.3:1 which would create huge side lobes. 3) No mention of emissivity.

This one doesn't mention ambient temperature operating range, which implies room temperature only.

This is probablly the best value for trailer purposes.

[Pete Dumbleton]

You don't need glasses to know where IR is, it's everywhere, so it's big, very big. Everything with a temperature above 0 degrees K emits IR energy. Now how do you keep IR energy from adversely effecting people?

You're right -- I was envisioning the "spot" that the IRT is reading as a projection of the IRT and therefore standing out from its surroundings, but its actually like the "spot" that ones sees through a telescope, merely a defined area. I guess we're stuck with laser dots and crosshairs for the time being.

[Steve L.]

My Raytek (now a Fluke model) projects a circle of laser dots plus a center dot. The circle's size is in proportion to the scan ratio (in my case 12:1) which helps give a sense of the area being scanned. Kind of a nice extra feature.

[bgeery]

I purchased the high-end $40 Harbor Freight model with 12:1 beam width (they just replaced this model with another $40 model that's 8:1) . I've compared it with almost a dozen contact thermometers, and it has always been withing +/- 1 degree of the other thermometers. Better than the specs, and I trust it.