So...who do you believe (measuring instruments)?

[MikeP]

I had the opportunity today to compare the readings of 3 different IR guns...They were all different and on the same room temperature surface, indicated 73.2, 76.1 and 74.8. On a warm (not hot) engine they indicated: 133.4 139.8 136.6. Now I'm not saying that difference matters at all in the real world but it does make me wonder...how do we KNOW if any device is displaying the correct reading. IOW, if you tire pressure gauge shows 33PSI, how the heck do you know if it's really 33 PSI? We just generally assume that X brand of high quality (read, "high price") MUST be accurate.

As far as the IR guns, one was a Fluke 62 (around 100 bucks), one was a Craftsman (around 50 bucks) , and the other was CenTech (harbor freight - 35 bucks. I know we would all like to believe the Fluke was correct but how do we know that?

Basically, this comes down to any instrument and digital makes it worse BECAUSE due to the digital reading we tend to ASSUME an accuracy that it doesn't deserve. IOW, a digital gauge that shows 33.6 is taken as more accurate than an analog gauge that reads "about 33 and a half." But, of course, the digital gauge IS an analog gauge with a digital converter so now we have the accuracy of the analog part AND the accuracy of the digital part to consider. I'm rambling...sorry!

 

[jim rosenthal]

Well, you would compare each of them to a known object temp, and see which was most accurate. For example, the surface temp of an ice cube ought to be 32F, right? Or a pot of boiling water ought to be 212F. No doubt you will get better suggestions than mine, but you could start there.

 

[Avenger]

Read the Fluke manual about calibrating for surface emissivity. The Fluke should have an adjustment, the others may not. But if that setting isn't consistent they will all read differently. If the setting is not correct they will read wrong.

 

[rwappleton]

Mike,

You MUST be caught up on your projects!

I see the need for that kind of accuracy on voltage especially in today's low voltage environment.

But lets cover what I would use an IR gun for. water temp, exhaust manifold at each cylinder, turbo comparison, turbo bearings, oil temp and much more. It seems to me that the measurements will tell you what you need to know.

So my answer is do what Scroddy said or use the one that matches your outfit.

Back to my Jolt cola!

Russ

 

[SeaEric]

It is my medium term desire to live long enough to have the spare time currently being enjoyed by MikeP to explore the curious mysteries of life aboard a Hatteras Yacht.

 

[Tim Powell]

Darn Mike just average then and go to sleep.