Inferred thermometers
- Thread starter Welderman85
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I have used several brands, and even the cheap ones do OK, to a point. For the best results, a hard surface, the beam hitting it at a right angle, and not too far away is best. Distance probably is the biggest factor. Fluke is always top of the line, Raytech (sp? from memory} has done well. But even low costs ones do fairly well, +- a few degrees.
I have the one from Harbor Freight. I bought it to measure temps from the AC ducts from my central air. But now I use it to measure the temps on the wood stove and flume pipe. Works good. I also ordred my father-in-law one from amazon. Works good too. Both were under $20 each.
I have an expensive one I inherited from a prior employer. Its well built but I rarely take it out of the box as my cheap Chinese one is half the size and seems to be just as accurate. The laser spotter doesn't project as far but for home use its fine. It probably is not built as well but for the price I wouldn't be real upset about throwing it away.
Note I assumed you are looking for a infrared temperature device as I have never seen an inferred one in the title.
Note I assumed you are looking for a infrared temperature device as I have never seen an inferred one in the title.
Whether you go with Chinese electronics with a Chinese label on the case, or Chinese electronics with an American label on the case, they are all going to read about the same - and pretty darned acurately - all things considered. The two biggest things I see driving 'incorrect' readings:
1) Know the emissivity of the surface. Most IR guns are 'tuned' for an emissivity of about 0.90 - as that is roughly what most surfaces are ...concrete, paint, plaster, wood, glass, etc. If you start getting into other surfaces... polished aluminum, polished stainless steel (likely the big one for us), shiny/clean steel, polished brass, etc - the emissivity is much lower and will also cause a much lower (incorrect) reading on the IR gun.
www.engineeringtoolbox.com
2) If the gun does come with a 'laser pointer' - know that the laser dot only denotes the center of a 'field of view' and everything in that field of view is measured / averaged. Typical guns will have a 10:1 or 12:1 field of view, or similar... so roughly 1" diameter for every 12 inches out from the gun... 12 feet away, you're measuring the average temp of a 1 foot circle centered on the laser dot.
I've seen guys shoot that laser at a 1/2" copper pipe 30 feet away, then try to tell me with 'certainty' what the exact temp of that pipe is just because the laser was 'touching' the pipe!
1) Know the emissivity of the surface. Most IR guns are 'tuned' for an emissivity of about 0.90 - as that is roughly what most surfaces are ...concrete, paint, plaster, wood, glass, etc. If you start getting into other surfaces... polished aluminum, polished stainless steel (likely the big one for us), shiny/clean steel, polished brass, etc - the emissivity is much lower and will also cause a much lower (incorrect) reading on the IR gun.
Surface Emissivity Coefficients
The radiation heat transfer emissivity coefficients for some common materials like aluminum, brass, glass and many more.
www.engineeringtoolbox.com
2) If the gun does come with a 'laser pointer' - know that the laser dot only denotes the center of a 'field of view' and everything in that field of view is measured / averaged. Typical guns will have a 10:1 or 12:1 field of view, or similar... so roughly 1" diameter for every 12 inches out from the gun... 12 feet away, you're measuring the average temp of a 1 foot circle centered on the laser dot.
I've seen guys shoot that laser at a 1/2" copper pipe 30 feet away, then try to tell me with 'certainty' what the exact temp of that pipe is just because the laser was 'touching' the pipe!
