Sheath/Wire/Insulation Properties


TABLE 1
THERMOCOUPLE WIRE TYPES
THERMOCOUPLE COMBINATIONS Calibration Type ARi SYMBOL STANDARD LIMITS OF ERROR RECOMMENDED TEMPERATURE RANGE
Platinum 10% Rhodium (+) Vs. Platinum (-) S S
±1.5șC or .25% Per ASTM E-230
0-1450șC
Platinum 13% Rhodium (+) Vs. Platinum (-) R R
±1.5șC or .25% Per ASTM E-230
0-1450șC

Platinum 30% Rhodium (+) Vs. Platinum 6% Rhodium (-)
B B ±0.5% 870-1700șC
Tungsten 5% Rhenium (+) Vs Tungsten 26% Rhenium (-)  C AE ±4.4șC (0-426șC)
±1% (426-2315șC)
Per ASTM E-988

0-2200șC

 

Tungsten 3% Rhenium (+) Vs. Tungsten 25% Rhenium (-) D AO ±4.4șC (0-426șC)
±1% (426-2315șC)
Per ASTM E-988

0-2200șC

 

 

TABLE 2
SHEATH MATERIALS
SHEATH TYPE ARi SYMBOL RECOMMENDED MAX. TEMP MELTING TEMP. ALLOWABLE ENVIRONMENT STD SHEATH DIAMETERS
(inches)
MIN. BEND RADIUS
Inconel 600 B 1175șC. 1345șC. Inert, Vacuum, Oxidizing 0.040, 0.062, 0.125, 0.188, 0.250 5 X Sheath Diameter
Platinum 10% Rhodium AH 1550șC. 1850șC. Inert, Oxidizing 0.040, 0.062, 0.125 5 X Sheath Diameter
Tantalum N 2200șC. 2995șC. Inert, Vacuum 0.040, 0.062, 0.125 10 X Sheath Diameter
Molybdenum O 2000șC. 2620șC. Inert, Vacuum, Reducing 0.062, 0.125, 0.188, 0.250 Do Not Bend
Niobium 1% Zirconium AV 2200șC. 2495șC. Inert, Vacuum 0.062, 0.125 10 X Sheath Diameter
Coated Molybdenum OCR 1600șC. 2000șC. Inert, Oxidizing 0.125, 0.250 Do Not Bend

 

TABLE 3
INSULATION MATERIALS
INSULATION TYPE  ARi SYMBOL RECOMMENDED MAX. OPERATING TEMPERATURE APPROXIMATE MELTING TEMP. COMMENTS
Magnesia 
(MgO)
N 1700șC. 2800șC. Very hygroscopic. Used mostly in compacted sheaths.
Alumina Oxide (Al2O3 ) A 1550șC. 2040șC. Excellent with Platinum alloys.
Hafnia Oxide
(HfO2)
H 2200șC. 2790șC. Comparable to Beryllia Oxide and safe to handle
Beryllia Oxide*
(BeO)
B 2200șC. 2650șC. Excellent High Temperature thermal conductivity and resistivity.

*Beryllia is considered a toxic material and can cause health problems if particles are inhaled.

 

TABLE 4
SHEATH DIAMETER CODES
SHEATH DIAMETER
(inches)
ARi Letter Code
0.040 A
0.062 B
0.125 D
0.188 E
0.250 F

 

TABLE 5
JUNCTION NUMBER CODES
SHEATH TYPE WIRE TYPE LETTER TYPE JUNCTION CODE GROUNDED JUNCTION CODE UNGROUNDED
Inconel 600 R, S, & B (8.1) (9.5)
Platinum 10% Rhodium R, S, & B 8 9
Coated Molybdenum AE & AO N/A (9.3)
Tantalum R, S, B, AE, & AO (8.1) (9.5)
Molybdenum R, S, & B N/A (9.4)
Molybdenum AE & AO N/A (9.3)
Niobium 1% Zirconium AE & AO (8.1) (9.5)

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