Its emf characteristic deteriorates and its life
is shortened in applications when the thermocouple has no protection
against external vibration, oxidizing or reducing atmosphere, metal
vapor and other aggressive chemicals. We can stabilize its characteristics
for a long period of time when we protect it from direct exposure
to external condition by using a thermo-well. Another name for the
thermo-well is a protection pipe (tube).
Materials of thermo-wells for low temperature applications are PVC,
polyethylene, Teflon* and the like. For high temperature ceramics
are used. There are also metal thermo-wells, typically of stainless
steel. Metallic or nonmetallic pipe is selected depending upon application
requirement.
The drawing shows typical construction of a thermocouple with a thermo-well.
Other common designs are thermocouples with insulated coating and
sheath-type structure. |
 |
| *Teflon is the DuPont Company's trade name. |
| M-System has flexible solutions to meet your specific
application and requirements. Consult our Signal Conditioners Data
Library. |
|
What
is a thermocouple with a thermo-well?
It
is a thermocouple assembled in a thermo-well. See the drawing for its typical
construction. A thermo-well protects the thermocouple wires from physical
and environmental damage. Before assembling, the thermocouple wires are
insulated with insulation tubes.