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ARi High Temperature Thermocouple is used in applications where base metal thermocouples cannot be used because of excessive temperatures or severe atmosphere. ARi can provide a wide variety of wire combinations and sheath materials to meet the harshest demands. By selecting certain materials, temperature measurements up to 2300°C can be achieved.
ARi manufactures it’s own mineral insulated cable and many of our high temperature thermocouple are available in bendable sheath and longer lengths. This in-house capability enables us to manufacture a variety of custom material combinations. Applications include;
Processes include sintering, annealing and carburizing. While many process variables affect service life, there are two (2) important considerations for selecting the proper thermocouple for a particular application.
With this information, it is possible to use these tables to select a suitable wire, sheath and insulation combination. The physical requirements of the thermocouple (sheath diameter, junction type and termination style) can then be selected to complete the design. Of course, you can always contact our ARi sales staff for help in selecting the proper high temperature thermocouple.
Sheath Materials | ||||||
|---|---|---|---|---|---|---|
| Sheath Type | ARi Symbol | Maximum Temp (°C) | Melting Temp (°C) | Allowable Environment | Standard Sheath Diameter (inches) | Minimum Bend Radius |
| Inconel 600 | B | 1175 | 1345 | Inert, Vacuum, Oxidizing | 0.040, 0.062, 0.125, 0.188, 0.250 | 5X Sheath Diameter |
| Platinum 10% Rhodium | AH | 1550 | 1850 | Inert, Oxidizing | 0.040, 0.062, 0.125 | 5X Sheath Diameter |
| Tantalum | N | 2200 | 2995 | Inert, Vacuum | 0.040, 0.062, 0.125 | 10X Sheath Diameter |
| Niobium 1% Zirconium | AV | 2200 | 2495 | Inert, Vacuum | 0.062, 0.125 | 10X Sheath Diameter |
| Molybdenum | O | 2000 | 2620 | Inert, Vacuum, Reducing | 0.062, 0.125, 0.188, 0.250 | Do Not Bend |
| Coated Molybdenum | OCR | 1600 | 2000 | Inert, Oxidizing | 0.125, 0.250 | Do Not Bend |
Wire Types | ||||
|---|---|---|---|---|
| Thermocouple Combinations | Calibration Type | ARi Symbol | Standard Limits Of Error | Recommended Temperature Range |
| Platinum 30% Rhodium (+) Vs. Platinum 6% Rhodium (-) | B | B | ± 0.5% | 870 – 1700 °C |
| Tungsten 5% Rhenium (+) Vs. Tungsten 26% Rhenium (-) | C | AE | ± 4.4 °C (0 – 426 °C)* | 0 – 2200 °C |
| ± 1% (426 – 2315 °C)* | ||||
| Tungsten 3% Rhenium (+) Vs. Tungsten 25% Rhenium (-) | D | AO | ± 4.4 °C (0 – 426 °C)* | 0 – 2200 °C |
| ± 1% (426 – 2315 °C)* | ||||
| Platinum 13% Rhodium (+) Vs. Platinum | R | R | ± 1.5 °C or 0.25% ** | 0 – 1450 °C |
| Platinum 10% Rhodium (+) Vs. Platinum | S | S | ± 1.5 °C or 0.25% ** | 0 – 1450 °C |
*Per ASTM E-988
**Per ASTM E-230
Insulation Materials | ||||
|---|---|---|---|---|
| Insulation Type | ARi Symbol | Maximum Operating Temp (°C) | Approximate Melting Temp (°C) | Comments |
| Magnesia (MgO) | N | 1700 | 2800 | Very hydroscopic. Used mostly in compacted sheaths. |
| Alumina Oxide (Al²O³) | A | 1550 | 2040 | Excellent with Platinum alloys. |
| Hafnium Oxide (HfO²) | H | 2200 | 2790 | Comparable to Beryllium Oxide and safe to handle. |
| Beryllium Oxide (BeO)*** | B | 2200 | 2650 | Excellent High Temperature thermal conductivity and resistivity. |
***Beryllium is considered a toxic material and can cause health problems if particles are inhaled.
ARi Part Numbering Symbols/Codes | |||||||
|---|---|---|---|---|---|---|---|
| Wire Type | Symbol | Sheath Type | Symbol | Insulation Type | Symbol | Sheath Diameter (inches) | Code |
| S | S | Inconel 600 | B | Magnesia (MgO) | N | 0.040 | A |
| R | R | Platinum 10% Rhodium | AH | Alumina Oxide (Al²O³) | A | 0.060 | (.060)* |
| B | B | Tantalum | N | Hafnia Oxide (HfO²) | H | 0.062 | B |
| C | AE | Molybdenum | O | Beryllia Oxide (BeO) | B | 0.118 | (.118)* |
| D | AO | Niobium 1% Zirconium | AV | 0.125 | D | ||
| Coated Molybdenum | OCR | 0.177 | (.177)* | ||||
| 0.188 | E | ||||||
| 0.236 | (.236)* | ||||||
| 0.250 | F | ||||||
*Non-standard/ metric size.
Junction Number Codes | ||||
|---|---|---|---|---|
| Sheath Type | Wire Type Letter Code | Insulation Type Letter Code | GROUNDED – Junction Code | UNGROUNDED – Junction Code |
| Inconel 600 | R, S, B | N | (8.1) | 9 |
| Platinum 10% Rhodium | R, S, B | N | 8 | 9 |
| Coated Molybdenum | AE, AO | A | N/A | (9.4) |
| AE, AO | N, H, B | N/A | (9.3) | |
| Tantalum | R, S, B | A | (8.1) | (9.4) |
| R, S, B | N, H, B | (8.1) | (9.5) | |
| AE, AO | H, A | (8.1) | (9.3) | |
| AE, AO | N, B | (8.1) | (9.5) OR (9.3)* | |
| Molybdenum | R, S, B | A | N/A | (9.4) |
| R, S, B | N, H, B | N/A | 9 | |
| AE, AO | N, H, B, A | N/A | (9.3) | |
* Assembly style.
