a thermocouple? I had a couple of tcs give funky readings when more than
1/2" of the stuff came loose, or if another spot on the sheath was =
It's a problem . . . thermocouples are fragile, brittle and subject to
destructive oxidation. In applications where longevity matters they are =
in some sort of thermowell for mechanical and chemical protection. =
very fast response is desired this often actually improves reading =
by presenting more heat transfer surface to whatever is being measured, =
a little thermal inertia to "smooth" the reading. A thermowell also
generally also reduces electrical noise on the leads.
I've made some simple ones out of thinwall stainless steel tubing from a
local hardware store. Cut and bend to whatever length and shape you =
put a little dollup of heat sink compound in the "business end", crimp =
shut, and thread the TC into it until the bead is in the heatsink =
(as far as it will go ). The heatsink goop maximizes transfer from =
wall to the bead, but you don't want too much or the extra mass will =
down response. Less is better . . . remember that it will squish up the
tube when you crimp it. You want just enough to "connect" the bead to =
tube wall, and no more. You get longer sensor life, and consistent
placement from roast to roast with such a thermowell.
If you want faster response (as when measuring air temperatures) but =
want some degree of mechanical protection leave the tube end uncrimped =
let the bead hang out just beyond the end of the tube. You get =
placement, and the leads don't break from flexing. Doesn't give any
protection from oxidation, though.