Technical Reference    |    FAQs    |    Downloads    |    Site Map
Technical Reference 
»
 Common Temperature Transducers
»
 Thermocouple
»
 RTD
» Thermistor
»
 Humidity
» References
» Watlow
» Omega
   
 
  Thermocouple
When two wires composed of dissimilar metals are joined at both the ends and one of the end is heated, there is continuous flow of current in the thermoelectric circuit.   If this circuit is broken at the center, the open circuit voltage is a function of the junction temperature and the composition of two metals.   This arrangement is termed as Thermocouple.
All dissimilar metals exhibit this effect.  The most common combinations are given below.
 
Type Composition
Application Range
 T
 Copper (+) Vs. Nickel-45% Copper (-)
-330 to 660 oF
(-200 to 350 oC)
 J
 Iron (+) Vs. Nickel-45% Copper (-)
200 to 1400 oF
(95 to 760 oC)
 E
 Nickel-10% Chromium (+) Vs. Nickel-45% Copper (-)
200 to 1650 oF
(95 to 900 oC)
 K
 Nickel-14% Chromium (+) Vs. Nickel-5% Aluminum & Silicon (-)
200 to 2300 oF
(95 to 1260 oC)
 N
 Nickel-14% Chromium-1.5% Silicon (+) Vs. Nickel-4.5%
.Silicon-0.1% Magnesium (-)
1200 to 2300 oF
(650 to 1260 oC)
 R
 Platinum-13% Rhodium (+) Vs. Platinum
1600 to 2640 oF
(870 to 1450 oC)
 S
 Platinum-10% Rhodium (+) Vs. Platinum
1800 to 2640 oF
(980 to 1450 oC)
 B
 Platinum-30% Rhodium (+) Vs. Platinum-6% Rhodium
2500 to 3100 oF
(1370 to 1700 oC)
 
TOP 
Color Codes To Identify Thermocouple
Type ANSI MC96.1 T/C ANSI MC96.1 Extension
T   Brown
+Blue
-Red		   Blue
+Blue
-Red
J    Brown
+White
-Red		   Black
+White
-Red
E    Brown
+Purple
-Red		   Purple
+Purple
-Red
K   Brown
+Yellow
-Red		    Yellow
+Yellow
-Red
N Brown
+Orange
-Red		    Orange
+Orange
-Red
R None Established   Green
+Black
-Red
S None Established Green
+Black
-Red
B None Established Grey
+Grey
-Red
 
 
Integrity Of A Thermocouple System Can Be Improved By Taking These Precautions:
•
Use the largest wire possible, which will not shunt heat away from the measurement area.
•
Avoid mechanical stress and vibration which could strain the wire.
•
Avoid steep temperature gradients.
•
Use the thermocouple wire within its range.
•
Use a guarded integrating A/D converter.
•
Use proper sheathing materials in hostile environment to protect the thermocouple wire.
•
Use extension wire only at low temperatures and only in regions of small gradients.
•
Keep an event log and a continuous record of thermocouple resistance.
 
 
..Reference Links
Emf Vs. Temp Upper Temp. Limits Thermoelement Properties
Color Codes Theory Thermocouple-based applications
TOP 
 
 
Last Updated April 28, 2009
Copyright © 2008, G-Tek Corporation. All Rights Reserved.
Contact webmaster@gtek-india.com for any questions related to the website.
Privacy | Terms & Conditions | Legal
Address : 3, Mahavir Estate, Karelibaug, Vadodara - 390 018. Gujarat. India.
Ph. : 91 265 2461912 Fax : 91 265 2460127 E-mail : info@gtek-india.com