Peter Heckert <[email protected]> wrote: I will use a resistor in an aluminium housing as a heat source and two > thermoelements and two instruments. > One thermocouple will be in close metallic contact to the resistor and the > other will be isolated by a piece of duct tape. >
Duct tape is thick and a good insulator. This will definitely have a large effect. You do not have to bother with that test. If Rossi's video showed duct tape between the thermocouple and the metal surface, that was a big problem. I did not see that in the video. Did you? Duct tape is supposed to be a decent insulator. It is for binding ducts together. What I had in mind is for you to propose a test that would simulate an actual problem that Rossi might have made. He may have left an air gap. That is an easy mistake to make. You said that could be serious. So test that, or some other plausible problem. I did not seat the thermocopules well yesterday. At first I just plastered them on with a Band Aid, deliberately. Band Aids are designed to admit air to the skin, through the cotton. I figured that using a Band Aid would cause the most exposure to ambient air. I tried sticking them on by taping only the wire, with the end the TC bent over just touching the pipe, but that did not work. I put two TCs together at first to see if they registered the same temperature. They did. In most of the test I had them stuck on fairly tight, and insulated, as shown in the photo. I wanted to see if the presence of the cold pipe 1/2" away, and the cold air trapped under the strapping tape would affect the measurement. By the way, insulating did not appear to make a measurable change, but it is very hard to tell. The first measurements with Band Aids only were chaotic. That's not recommended! That was my idea of the "worst method imaginable." Way too rudimentary. I was not being serious, although I am curious about the effect of exposure ambient air. I have never heard of anyone leaving a TC exposed on a pipe surface. Rossi did a much better job mounting the TC that I did, as you see in the video. Yugo claims she cannot see where it is mounted. The location seems clear to me. Someone uploaded a still photo from the video showing the location. I don't know what she is talking about. - Jed
