| STANDARD ISA THERMOCOUPLE CALIBRATION INFORMATION |
|---|
LETTER
DESIGNATION
ANSI CODES |
CONDUCTOR
MATERIAL |
COLOR
CODE |
MAG-
NETIC |
TEMPERATURE
RANGE
(Degrees F) |
LIMITS OF ERROR
STANDARD SPECIAL
(% or Degrees F) |
APPLICATIONS |
|---|
| J |
IRON
CONSTANTAN |
+WHITE
-RED |
YES
NO |
32 - 530
530 - 1400 |
±4°
±3/4% |
±2°
±3/8% |
May be used in vacuum, oxidizing, reducing, and inert, atmospheres. Since iron oxidizes rapidly, use heavyguage wire above 1000 degrees F. This calibration is the most used becuase of its versatility and low cost. |
| K |
CHROMEL®
ALUMEL® |
+YELLOW
-RED |
NO
YES |
32 - 530
530 - 2300 |
±4°
±3/4% |
±2°
±3/8% |
Use in oxidizing atmospheres above 1000 degrees. Cycling above and below 1800 degrees should be avoided due to alterations in EMF caused by ageing of alloys. "Pre-ageing" of thermocouples prevents the action. Avoid using this calibration in reducing atmospheres. Preferential oxidation of chromium takes place in reducing atmosphere (commonly called "green rot"). This causes a large negative shift of EMF and rapid deterioration of the
thermoelement. |
| T |
COPPER
CONSTANTAN |
+BLUE
-RED |
NO
NO |
-300 - -75
-75 - +200
200 - 700 |
±2%
±1.5°
±3/4% |
±1%
±3/4°
±3/8% |
Resistant to corrosion in oxidizing / reducing atmospheres (avoid Chlorine). Best for Cryogenic applications. Do not use above 700 degrees F due to poor oxidation resistance of copper. |
| E |
CHROMEL®
CONSTANTAN |
±PURPLE
-RED |
NO
NO |
-300 - +600
600 - 1600 |
±3°
±1/2% |
N/A
N/A |
Has the highest EMF per degree of any standard thermocouple. Since one leg of this thermocouple is CHROMEL®, the same precautions used with type "K" should be taken. |
| N |
NICROSIL
NISIL |
+ORANGE
-RED |
NO
NO |
32 to 2300 |
±4° |
±3/8% |
Replaces "K". Does not exhibit preferential oxidation problem found with "K". Longer life and better stability than type "K". |
| S |
PLATINUM
10% RHODIUM
PLATINUM |
+BLACK
-RED |
NO
NO |
32 to 1000
1000 to 2700 |
±DEGREES
±1/4% |
N/A
N/A |
Avoid reducing atmospheres.
Will cause excessive grain growth resulting in calibration drift (up to -2 mv). |
| R |
PLATINUM
13% RHODIUM
PLATINUM |
+GREEN
-RED |
NO
NO |
32 to 1000
1000 to 2700 |
±DEGREES
±1-4% |
N/A
N/A |
N/A Avoid reducing atmospheres.
Will cause excessive grain growth resulting in calibration drift (up to -2 mv). |
| B |
PLATINUM
30% RHODIUM
PLATINUM
6% RHODIUM |
+GREY
-RED |
NO
NO |
32 to 1000
1000 to 2700 |
±DEGREES
± 1/4% |
N/A
N/A |
Avoid reducing atmospheres.
Will cause excessive grain growth resulting in calibration drift (up to -2 mv).
|
| NO ANSI CODES |
| W |
TUNGSTEN
TUNGSTEN
26% RHENIUM |
+WHITE
-RED |
NO
NO |
32 to 4208 |
±1% |
N/A |
Vacuum or inert atmospheres only.
Very high temp applications only. |
| C (W5) |
TUNGSTEN
5% RHENIUM
TUNGSTEN
26% RHENIUM |
+WHITE
-RED |
NO
NO |
32 to 4208 |
±1% |
N/A |
Somewhat less brittle than W. |
19 ALLOY /
20 ALLOY |
Ni-18Mo
Ni-1Co |
+N/A
-N/A |
YES
YES |
32 to 2300 |
±3/4% |
N/A |
Developed for measuring temps. in hydrogen or reducing atmospheres. Should not be used in oxidizing atmospheres. |
| OTHER TYPES OF THERMOCOUPLES USED PRIMARILY FOR
SPECIAL APPLICATIONS. |
| PLATINEL II® |
Approximates the type "K" curve. Can be used unprotected in air for extended periods of time.
Has less drift than type K if aged in hydrogen for 1000 hrs. at 1000 degrees C. Cannot be used in
sulfur, phosphorus or silicon atmospheres. |
IRIDIUM /
RHODIUM |
Can be used for short periods of time up to 2180 degrees C.
Can be used in inert atmospheres and in vacuum. Cannot be used in reducing atmospheres. |
PLATINUM -
MOLYBDENUM |
Used for measuring temperatures from 1100 to 1500 degrees C. under neutron radiation. You cannot use Platinum thermocouples containing Rhodium in neutron radiation due to rhodium being transmuted into palladium under neutron bombardment. |
