I'll check out all the info given by you and dcara.

I want to take measurements on a number of different exhaust configurations. I need tape on or clip on sensors that can be quickly installed on a truck before its dyno run, and then removed to install on another truck. I plan to stand at the side of the dyno, and video the 3 multi-meters and my pressure gauge in a common frame, along with some voice over comments and the sound of the engine in the background. I'm also looking into acoustic analysis software, and considering recording the exhaust note at the tailpipe exit with another microphone and digital recorder.

After I study my book, which I still haven't received, I'll probably get some more ideas about other things to measure as well.

 

the teflon tape you can get any harware store, I am going to have to find a source for the other stuff, sorry, i will look into it, and let you know.

 

The more surface area there is (i.e. larger diameter) the more heat sinking will occur and hence the larger the error. Hence, a long probe should be of minimum diameter to reduce errors. Don at ISSPRO told me yesterday that these thermocouples are type k.

Regarding the length of wire, reference readings on each thermocouple/meter pair should be made before and after any additional wire is added in order to determine any temperature offset due to voltage drop in the additional wire.

 

I am not sure I agree, or even disagree with what you said.. Normally what you have is a twisted pair, soldered at the tip, up inside of the sleeve. MAybe it is a matter of if the tip contacts the sleeve, or if it doesnt it is waiting for inner area to heat up...before is reconizes the temp. That would allow for the heatsinking, because it would now be ( lack of a better term) averaging the temp between the hot zone, and exposed area outside of the hot zone. That would also explain the slow reaction.

I called Duro Sense as i was typing this, the explanation given to me was "could be" where the tip of the wire was in relationship to the sheath. If the wire was tipped (twisted then soldered together) right at the thread of the thermo, you would most likely get your temp from there, if the thermo coupling wire is tipped at the very end of the sheath, you would likely get your temp from there. There is supposed to be an insulation around the wire up to where the wire is tipped..

I am really looking forward now to my next TC failure so I can gut one of these.

As far as adding wire, you are correct about the changes it could have, but all of the wire i have here is normally certified to be with in +/- 3* over 100' of length. 300* to what ever temp, and with a calibration meter I have found it be accurate even under the 300*, up to 2700*.

 

As far as purchasin Glyptol, havent found out where I bought it yet, but here is a link to help
http://www.listserve.com/archives/co.../msg00367.html

 

"but all of the wire i have here is normally certified to be with in +/- 3* over 100' of length. 300* to what ever temp, and with a calibration meter I have found it be accurate even under the 300*, up to 2700*."

Sounds like you have good info on that issue. None-the-less, it is prudent to check calibration of the test set up before the actual test is conducted to check for bad connections, and general correct/expected equipment operation.

Don at ISSPRO told me yesterday that his termocouple wires are connected at the tip and then arc welded to the inside tip of the stainless steel sheath. The sheath is then filled with ceramic filler for heat isolation and to hold the wire in the center of the sheath.

I believe your are correct about the heat sinking effect effect that would be observed if the wires were not connected to the inside of the sheath. However, there is also the effect of external heatsinking that is demonstrated by my maxread pic. Heat sinking is also a function of temperature differential. YThe greater the temperature difference the more heat transfer/sinking occurs. For instance one thing I didn't mention specifically that I observed in my previous tests was that even though there was lag the ISSPRO would eventually read the same as my reference thermocouple up to the maxread level.

Soon I will try my new thermocouple and gauge and see what happens.

 

Have fun, let us know, like I said I am gutting one these here soon. Good talking with you on this.