|
A vacuum furnace manufacturer
employs a heat treating process
in which the metal parts experience an
electrical potential of 1000 volts. To control the heating
process to produce the correct metallurgical properties,
a conventional thermocouple embedded in
one of the parts produces the temperature signal for
the controller. However, since the parts are at 1000
volts, an elaborate electrical isolation system has
to be employed to permit the thermocouple to work
safely, at a cost of well over $2,000.
Replacing the contact thermocouple
with a non-contact IRt/c, the
manufacturer effectively replaced $2,000
worth of equipment with about 1 inch (2.5 cm)
of vacuum separation between the IRt/c and test
part - which is free. Unlike a contact thermocouple, the IRt/c can easily see the part through the
vacuum,
measure its temperature without touching, remaining
completely isolated electrically by the gap between
the part and IRt/c. Since the part is heated to
1000°F (538°C), an aluminum clamp is employed as
a heat sink to keep the IRt/c itself below 200°F (93°C).
Since the part emissivity is low (shiny metal) the
test part has a small area painted with RustoleumŽ
Barbecue Black Paint, rated to 1300°F (704°C),
to raise the emissivity.

|