Thermocouple Accuracy Table by Type and Temperature

Updated Jan 14, 2019

Reported In

Hardware

  • C Series Temperature Input Module
  • C Series Temperature Input Device
  • Temperature Input Device

Issue Details

  • What is the temperature accuracy that I can expect from thermocouple sensors?
  • I am reading the temperature of a chamber using two thermocouples of the same type but the readings are different. I have calculated the accuracy of my measurement hardware but it does not compensate for the difference in readings. What may be causing this phenomenon?

Solution

When talking about accuracy, you should consider the accuracy of the measurement hardware, as well as the inherent accuracy of the thermocouple. The accuracy of a thermocouple is affected by its type and temperature. See the table below for the maximum permitted error (in degree Celsius) for various common thermocouples that comply with IEC 584-2 (1982). 
 
 
TemperatureB TypeE TypeJ TypeK TypeN TypeR TypeS TypeT Type
-200---3.03.0--3.0
-100---2.52.5--1.5
0-1.71.51.51.51.01.00.5
200-1.71.51.51.51.01.00.8
400-2.01.61.61.61.01.0-
6001.53.02.42.42.41.01.0-
8002.04.0-3.23.21.01.0-
10002.5--4.04.01.01.0-
12003.0--9.09.01.31.3-
14003.5----1.91.9-
16004.0----2.52.5-

In addition to accuracy based on the type of thermocouple, thermocouples have a specified range of temperatures over which they can operate. This can become a problem when extreme high temperatures are being read. Their ranges are determined by numerous variables, including the following:
  1. Type (i.e. J, K, E, T, RX/SX, N, CX)
  2. Sheath material
  3. Sheath diameter

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