B).IRON – CONSTANTAN (J TYPE)

24 Field Instrumentation GEN Rev)
E). PLATINUM RHODIUM/PLATINUM (RB, S TYPE)
•
• This thermocouple is used in Oxidizing atmosphere.
• In R type thermo couple, pt = 87% & Rh = 13%
• Range Up to +2700 o
F
• In S type thermo couple, pt = 90% & Rh = 10%
• Range 0 o
F to +2100 o
F
• In B type thermo couple, pt = 70% & Rh = 30%
• Range 1472 o
F to +3092 o
F
TEMPERATURE
RANGES
OF
DIFFERENT
THERMOCOUPLES

25 Field Instrumentation GEN Rev)

26 Field Instrumentation GEN Rev) An extension wire made of the same material as the thermocouple is referred to as thermocouple wire, but a wire made of different material (with characteristics similar to the thermocouple’s) is referred to as compensating lead wire. thermocouple wire can be used for type T and J because material is not expensive. Compensating lead wire is normally made of copper or copper/nickel alloy.
A
PICTURES
EXPLAINING
THE
REFERENCE
JUNCTION
OF
A
THERMOCOUPLE

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