Thermocouples are the most widely used electronic temperature sensor. Their advantages include reasonable cost, wide variety of styles, wide temperature ranges, normally fast speed and better durability than other sensor types.
ThermoWorks certifies that our Type K probes have been tested, inspected and found to conform to an accuracy of ±0.5°C over the range of 0°C to 100°C.
Many probes can be ordered with a flat cable or a coiled, retracting cable. Standard cable length is 39" (1 meter) unless otherwise indicated. We can also supply longer cable lengths on request and custom probe lengths or diameters. Custom probes or other thermocouple types generally require about 3 weeks for delivery.
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What does the Time Constant specification mean?
As defined by engineering sciences, a time constant is the actual time that a physical system requires to reach 62.3% of its total value. After 5 time constants, the system is considered to be at 100% value.
How do you translate 1 time constant into the time it takes a temperature probe to reach the full value of the system being measured? Multiply the time constant specification by 5 to get the time to reach full value. Here's a typically example:
Time Constant = 0.5 seconds (typically given for liquid measurements)
Results can vary with the medium being measured. Thermally speaking, liquids transfer heat faster than air so sufficient time must be allowed for the probe sensor to reach thermal equilibrium with the air. Moving air will be faster than standing air or room/ambient temperature measurements.
What is Accuracy?
NIST defines accuracy as: closeness of the agreement between the result of a measurement and the value of the measurand or "true value".
Thermocouple accuracy is typically defined by the type of wire used, i.e. Standard Limits of Error (4.0°F) and Special Limits of Error (2.0°F). Unless otherwise noted, ThermoWorks employs high performance thermocouple wire with tighter tolerances than Special Limits of Error wire over common industrial ranges in its probe construction. Probe tolerances are listed below: