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- STABILIZED Type K Reduced Drift Thermocouple
Wire
THE PROBLEM
Type K* thermocouples are known to yield accurate temperature
measurements in the 1,000F (538C) range for short duration
exposures. However, after extended exposure in the 650F (343C)
to 1100F (593C) range, Type K material may exhibit a
positive drift in readings of up to 6F (3C) at 1,000F (538C)
and as much as 9F (5C) at 2,000F (1093C). This drifting could
prove disastrous in applications such as heat treating where
temperatures must be increased gradually and sustained in the
drifting range for as little as one hour.
The change in thermoelectric properties is generally attributed
to "atomic ordering". When the Type K thermocouple
is used
in the drifting range, some of the atoms of the positive thermoelement
rearrange themselves from a random state into an
ordered state. This atomic rearrangement changes the EMF output
of the conductor. Type K EMF drift causes the temperature
reading to appear higher than it actually is. Any error caused
by non-stabilized Type K drift is in addition to the initial
calibration tolerance deviation of the Type K material. For
example, a heat treat operation running at 2,000F (1093C) using
non-stabilized standard limits Type K material could experience
an initial tolerance calibration deviation up to 15F (9C)
PLUS another 9F (5C) drift error, meaning that the process could
actually be running 24F (14C) lower than the thermocouple
EMF output shows. This equates to an error of greater than 1%.
THE SOLUTION
TE Wire & Cable offers STABILIZED Type K wire
constructions. STABILIZED Type K was developed by
TE Wire & Cable through years of experience,
and testing. All STABILIZED Type K constructions are engineered
around wire that has been manufactured using proprietary processes
which essentially "lock in" the high temperature calibration.
This is a characteristic which is not addressed by non-stabilized
Type K thermocouple wire. The proprietary process involves
many procedures and not just a heat treatment of the conductors.
Heat treatment alone does not stabilize the wire.
When long term temperature control accuracy is required or if
Type K drift is a problem, STABILIZED Type K from
TE Wire & Cable is the answer.
* Type E thermocouples are similarly affected. Stabilized E
constructions are also available.
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