Exhaust gas temp measurement

[Rudi M. Machilek]

Agreed on the material selection.  The vibration problem I have experienced
on a range of applications was on the cold side sticking out from the
exhaust manifold.  We were snapping-off lead wires, had connectors coming
apart and such.  An aluminum bracket to tie that end down took care of the
problem.  When we tried smaller 1/16" sheath thermocouples (trying for
response times we never got), a week or two was all we got with Inconnel.
We would loose the element just at the base of the fitting in the exhaust
manifold.  We attributed it to resonance from the near sonic port flow and
mechanical vibration.  The Abarth 850 was the worst, but it seemed to
vibrate badly anyway, so that example my not be fair. The 3/16" diameter
elements did not exhibit this problem.

Rudi

>Either a 321 SS, 347 SS, or Inconel sheath will not only stand up to the
heat better, but will not be >nearly as likely to crack from the vibration.
Cracking (due to intergranular corrosion) _IS_ the failure
>mode of 304 SS at high temps. The vibration is not that much of a problem,
even at high temps, with >the correct alloy.


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