California Fine Wire CompanyDefinitions Relevant to Thermocouple Wires California Fine Wire Company

ANSI: American National Standards Institute

COMPENSATING ALLOYS: Alloys used to connect thermocouples to instrumentation. These alloys are selected to have similar thermal electric properties as the thermocouple alloys.

Emf: The electrical potential difference, which produces or tends to produce an electric current (Electromotive force).

EXTENSION GRADE: A pair of wires having such a temperature/emf characteristics relative to the thermocouple with which the wires are intended to be used that, when properly connected to the thermocouple, the reference junction is transferred to the other end of the wires.

LIMITS OF ERROR: A tolerance band for the electric response of thermocouple wire expressed in degrees or percentage as defined by ANSI specification MC-96.1.

Notes:

1. The limits of error for each type of thermocouple apply only over the temperature range for which the wire size in question is recommended.

2. Limits of error apply to thermocouples as supplied by the manufacturer. The calibration of a thermocouple may change during use.

MEASURING JUNCTION: The thermocouple junction referred to as the hot junction that is used to measure an unknown temperature.

REFERENCE JUNCTION: That junction of a thermocouple, which is at a known temperature.

THERMOCOUPLE: A device for measuring temperatures, consisting of two dissimilar metals which produce an electromotive force (emf) roughly proportional to the temperature difference between their hot and cold junction.

THERMOELEMENT: One of the two dissimilar electrical conductors comprising a thermocouple.

California Fine Wire CompanyTHERMOELEMENT TYPES AND DESCRIPTIONS:California Fine Wire Company

TYPE

DESCRIPTION

J

Iron/Constantan

K

Chromel®/Alumel®

T

Copper/Constantan

E

Chromel®/Constantan

R

Platinum 13% Rhodium/Platinum

S

Platinum 10% Rhodium/Platinum

B

Platinum 30% Rhodium/Platinum
 

Tungsten/Tungsten 26% Rhenium
 

Tungsten 5% Rhenium/Tungsten 26% Rhenium
 

Tungsten 3% Rhenium/Tungsten 25% Rhenium

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