THERMOCOUPLE : TYPES, CONSTRUCTION, DETAILS

THERMOCOUPLE TYPES AND DETAILS :


Basically their are four types of Thermocouples according to the construction metals.
(i) Base Metal Thermocouple
(ii) Nobel Metal Thermocouple
(iii) Refractory Metal Thermocouple

(i) Base Metal T/C

Sr.
no
Type
Conductor Metals 
Color code
Range
EMF range(mV)
Sensitivity
1
T
Cu(+ve) – Constantan(-ve)
Blue- +
Red-  -
-270°C – 400°C
-6.258 – 20.869
40.5
2
J
Fe(+ve) –Constantan(-ve)
White- +
Red-  -
-210°C-1200°C
-8.046 - 69.536  
52.6
3
K
Chromel(+ve) –Alumel(-ve)
Yellow- +
Red-  -
-270° C-1370°C
-6.458 – 54.807
38.8
4
E
Chromel(+ve) –Constantan(-ve)
Purple- +
Red-  -
-270°C-1000°C
-9.835 - 76.358
67.9
5
N
Nicrosil(+ve) –Nisil(-ve)
Orange- +
Red-  -
-270°C - 1300°C
-4.345 – 47.502
39

(ii) Nobel Metal T/C

Sr.
no
Type
Conductor Metals
Color code
 Range
EMF range (mV)
Sensitivity
1
S
[Pt(90%)+Rhodium(10%)] –Pt(-ve)
Black- +
Red-  -
-50℃ - 1760℃
-0.236 - 18.612
10.6
2
R
[Pt(87%)+Rhodium(13%)]
(+ve) –[Pt(94%)+Rhodium(6%)](-ve)
Black- +
Red-  -
-50℃ - 1700℃
-0.026 – 21.006
12
3
B
[Tungsten(94%)+Rhodium(6%)]
(+ve) –[Tungsten(74%)+Rhodium(26%)]
(-ve)
Grey- +
Red-  -
0℃ - 1820℃
0 – 13.814
7.6

  (iii) Refractory Metal T/C



Sr.
no
Type
Conductor Metals
Color
code
Range
EMF range
(mV)
Sensitivity
1
C
[Tungsten(94%)+Rhodium(6%)]
(+ve) –[Tungsten(74%)+Rhodium(26%)]
(-ve)

     ---
0℃ - 2400℃

      ---

       ---
2
G
Tungsten (+ve) –[Tungsten(74%)+Rhenium(26%)]
(-ve)

    ---
0℃ - 2400℃

       ---

       ---
3
D
[Tungsten(97%)+Rhenium(3%)] (+ve)–[Tungsten(74%)+Rhenium(25%)]
(-ve)

    ---
0℃ - 2400℃

       --- 

       ---

 (iv) Special T/C


Sr.
no
Type
Conductor Metals
Color
code
Range
EMF range
(mV)
Sensitivity
1
---
[Indium(60%)+Rhodium(40%)]
(+ve) –Indium (-ve)
   ---
0℃ - 2000℃
    ---
    ---
2
---
Tungsten (+ve) –Molybdenum (-ve)
   ---
1250℃ – 2600℃
    --- 
    ---
3
---
[Gold(50%)+Iron(50%)] (+ve) –Chromel (-ve)
   ---
-270℃ - 0℃
    ---
    ---


NOTE:

⏺ We can get the maximum sensitivity(67.9) from the E-type Base metal Thermocouple 
⏺ [-270℃- 0℃] range is called Cryogenic range

Read Also....

BASIC DIGITAL LOGIC GATES: http://www.theincredibletruths.com/search/label/www.theincredibletruths.com%3EBasic%20Digital

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