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TPI Probe Fact Guide
What is the difference between thermocouple and thermistor probes?
Thermocouple probes utilize the reaction between two
dissimilar metals to produce a voltage that changes as
temperature changes. A thermistor is a resistive device
that produces a change in resistance with a change in
temperature. In general, thermocouples offer a wider
temperature range and quicker response time than
thermistors. Thermistors are typically more accurate
than thermocouples.
How are thermocouple types different?
Each thermocouple uses different metals and therefore
have different characteristics. Here are general guidelines:
K-Type: Wide temperature range, use in many digital
thermometers and multimeters. Identify by yellow
connector.
J-Type: Narrower temperature range than K-type, use in analog
and digital thermometers. Identify by black connector.
T-Type: Narrower temperature range than J-type but more
accurate than K and J types, use in digital thermometers.
Identify by blue connector.
Can different thermocouple types be interchanged?
No. Since each thermocouple type is constructed with
different metals they have different output characteristics.
Using a J-type thermocouple in a K-type thermometer
will cause measurements to be very inaccurate.
What type of probe should I use?
Probe type used depends on the specific application.
General guidelines for different probe types follow:
Penetration: General-purpose probe used for immersion and
air temperature measurements. Response time in air is
slower than an air probe because the tip is not exposed.
Chisel: General-purpose tip used for surface, immersion, and
air temperature measurements. Response time in air
or on surfaces is slower than an air or surface probe
because of the tip design.
Air: Exposed tip probe provides the fastest response
time when measuring air temperatures. Not useful
for surface or immersion testing.
Surface: Contact tip probe provides fastest response time
when measuring surface temperatures. Probe tip offers
maximum temperature transfer in surface applications.
Not useful for air or immersion testing.
Beaded: General-purpose probe used in immersion and air
temperature measurements. Exposed tip allows for
fast reaction time. Not useful in semi-solids. |
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