Tempco offers a wide variety of sheathed, mineral insulated, thermocouple cable. We stock many varieties of sheath diameters and materials in ANSI recognized thermocouple types and can manufacture a multitude of non-stock combinations of sheath materials, O.D.'s, insulations, wire types and wire configurations on special request, consult Tempco with your specific requirements.

Tempco-Pak Thermocouples and cable are manufactured using premium quality materials along with rigid quality control standards to insure a reliable product that is state-of-the-art. The metal outer sheath protects the thermocouple wires and insulation from contamination and mechanical damage, hostile and oxidizing environments, while allowing it to be moisture proof, formable, weldable, compact and have fast response. The mineral insulation isolates the conductors from the sheath and each other while providing excellent high temperature insulation resistance.

Tempco offers a wide variety of sheath materials to choose from as there is no single sheath material that is suitable for all conditions. The most commonly stocked sheath materials are 304 S.S., 316 S.S. and alloy 600. These are offered in all ANSI recognized thermocouple calibrations.

As a standard, Tempco-Pak Thermocouple cable is made with high purity 94% minimum MgO insulation. Other types and purities are available; however, when selecting a mineral insulation, the environment, temperature rating and cost must be taken into consideration.

Tempco-Pak 

Thermocouple Data, Care and Handling

Calibration
Tempco-Pak Thermocouple Cable is normally supplied to ANSI standard limits (tolerances) of error as set forth in ANSI circular MC96.1-1982 and duplicated in ASTM E230. Special limits (tolerances) per ANSI MC96.1 are available at extra cost. (See Table 1 below.)

Annealing
Unless otherwise specified all Tempco-Pak will be furnished in a fully annealed condition.

Formability
Because Tempco-Pak is fully annealed it can normally be formed around a mandrel 4 times the sheath diameter without loss of insulation resistance or the sheath's integrity.

Insulation Resistance
Tempco-Pak should have a minimum insulation resistance wire to wire and wire to sheath at room temperature of 100 megohms at 50 VDC for 0.093" O.D. and smaller and 100 megohms at 100 VDC for .100" O.D. and larger.

Shipping and Packaging
Tempco-Pak is stocked in random lengths with the maximum stock lengths listed in the tables showing the varieties of commonly available material. Tempco reserves the right to supply random lengths of our choice unless specific lengths are specified on your order. Tempco-Pak can be furnished in coil form or in straight lengths. Normally .375" diameter and .312" diameter are shipped in straight lengths. Longer lengths are available on special order.

The following information is designed to be used as a guide and may not be correct in every application. If in doubt, consult with your Tempco sales engineer or the factory. Temperatures shown are maximum recommended operating temperatures.

Sheath Material
Note: Letters in parenthesis following the sheath material are used with the Ordering Worksheet.

304 SS (B)
Maximum temperature: 900ºC (1650ºF). Most widely used low temperature sheath material. Extensively used in food, beverage, chemical and other industries where corrosion resistance is required. Subject to damaging carbide precipitation in 482º to 871ºC (900º to 1600ºF) range. Lowest cost corrosion resistant sheath material available.

316 SS (C)
Maximum temperature: 900ºC (1650ºF). Best corrosion resistance of the austenitic stainless steel grades. Good corrosion resistance in H2S. Widely used in the food and chemical industry. Subject to damaging carbide precipitation in 482º to 871ºC (900º to 1600ºF) range.

304L (D)
Maximum temperature: 900ºC (1650ºF). Low carbon version of 304 SS (B). Low carbon content allows this material to be welded and heated in the 482º to 871ºC (900º to 1600ºF) range without damage to corrosion resistance.

316L (E)
Maximum temperature: 900ºC (1650ºF). Same as 316 SS (C) except low carbon version allows for better welding and fabrication.

310 SS (F)
Maximum temperature: 1150ºC (2100ºF). Mechanical and corrosion resistance, similar to but better than 304 SS. Very good heat resistance. This alloy contains 25% Cr, 20% Ni. Not as ductile as 304 SS.

321 SS (G)
Maximum temperature: 871ºC (1600ºF). Similar to 304 SS except titanium stabilized for intergranular corrosion. This alloy is designed to overcome susceptibility to carbide precipitation in the 482º to 871ºC (900º to 1600ºF) range. Used in aerospace and chemical applications.

Nickel 201 (K)
Maximum temperature: 1093ºC (2000ºF). Commercially pure wrought nickel with low carbon. Used in molten salt bath furnaces. Offers good resistance to caustic alkalines and fluorine.

Pure Platinum (M)
Maximum temperature: 1482ºC (2700ºF). Platinum is the only metallic material capable of operating in an oxidizing atmosphere above 1260ºC (2300ºF) for extended periods of time. Normally used with type R, S or B conductors. Used in glass manufacturing, high temperature furnaces and as control standards.

Platinum 10% Rhodium (N)
Maximum temperature: 1552ºC (2825ºF). Excellent oxidation resistance. Same type of uses as platinum 20% rhodium except lower cost and reduced operating range.

Platinum 20% Rhodium (P)
Maximum temperature: 1649ºC (3000ºF). Excellent oxidation resistance. Very expensive oxidation resistant alloy used in glass manufacturing and in research applications. Also used for gas turbine test thermocouples.

Hastelloy X® (Q)
Maximum temperature: 1204ºC (2200ºF). Widely used in aerospace applications. Resistant to oxidizing, reducing and neutral atmospheric conditions. Excellent high temperature strength along with superior oxidation resistance. Resistant to stress corrosion cracking in petrochemical applications.

Inconel® 601 (R)
Maximum temperature: 1177ºC (2150ºF) Continuous; 1260ºC (2300ºF) Intermittent. Similar to Alloy 600 with the addition of aluminum for outstanding oxidation resistance. Designed for high temperature corrosion resistance. This material is good in carburizing environments, and has good creep rupture strength. Do not use in vacuum furnaces! Susceptible to intergranular attack by prolonged heating in 538º to 760ºC (1000º to 1400ºF) temperature range.

Incoloy® 800 (S)
Maximum temperature: 1093ºC (2000ºF). Widely used as heater sheath material. Minimal use in thermocouples. Superior to Alloy 600 in sulfur, cyanide salts and fused neutral salts. Susceptible to intergranular attack in some applications by exposure to the temperature range of 538 to 760ºC (1000º to 1400ºF).

Incoloy® 800HT (T)
Maximum temperature: 1093ºC (2000ºF). Same as Incoloy 800® (S) except carbon content is limited to upper end of range. This provides significantly higher creep and rupture strength. Used in the chemical and petrochemical industry for long term exposure to high temperatures.

Molybdenum (V)
Maximum temperature in air: 399ºC (750ºF). Melting point: 2610ºC (4730ºF). Refractory metal. Brittle; cannot be bent. Use only in inert, vacuum or reducing atmospheres. Most commonly used with BeO insulation and Tungsten Rhenium conductors. Uncompacted assemblies only.

Insulation
Note: Letters in parenthesis following the insulation material are used with the Ordering Worksheet.

Beryllium Oxide--BeO 99.7% Minimum Purity (B)
This excellent high temperature insulation is used primarily with tungsten rhenium conductors and either a molybdenum or tantalum sheath. Beryllia is the only material other than diamond which combines excellent electrical insulating properties along with high thermal conductivity. The two disadvantages of this material are cost, (approximately 10x  greater than MgO), and the toxicity of BeO. Beryllia dust can cause potential health problems if it is inhaled. We highly recommend that assemblies containing Beryllium insulation be made at Tempco where our work stations are designed for handling this material. Maximum recommended temperature is 1900ºC (3452ºF).

Calibration
Note: Standard and Special Tolerance Calibration information to be used with the Ordering Worksheet.

Table
1

Tolerances in this table apply to new essentially homogeneous thermocouple wire, normally in the size range 0.25 mm to 3 mm in diameter (No. 30 to No. 8 Awg) and used at temperatures not exceeding the recommended limits of Table 1. If used at higher temperatures these tolerances may not apply.

The Fahrenheit tolerance is 1.8 times larger than the ºC tolerance at the equivalent ºC temperature. Note particularly that percentage tolerances apply only to temperatures that are expressed in ºC.

Caution: Users should be aware that certain characteristics of thermocouple materials, including the emf versus temperature relationship may change with time in use; consequently, test results and performance obtained at time of manufacture may not necessarily apply throughout an extended period of use. Tolerances given in this table apply only to new wire or MI cable or thermocouples as delivered to the user and do not allow for changes in characteristics with use. The magnitude of such changes will depend on such factors as wire size, temperature, time of exposure, and environment. It should be further noted that due to possible changes in homogeneity, attempting to recalibrate used thermocouples is likely to yield irrelevant results, and is not recommended. However, it may be appropriate to compare used thermocouples in-situ with new or known good ones to ascertain their suitability for further service under the conditions of the comparison.

Table
2

This table gives the recommended upper temperature limits for the various thermocouples and wire sizes. These limits apply to protected thermocouples; that is, thermocouples in conventional closed-end protecting tubes. They do not apply to sheathed thermocouples having compacted mineral oxide insulation.

The temperature limits given here are intended only as a guide to the user and should not be taken as absolute values nor as guarantees of satisfactory life or performance. These types and sizes are sometimes used at temperatures above the given limits, but usually at the expense of stability or life or both. In other instances, it may be necessary to reduce the given limits in order to achieve adequate service. ASTM MNL-125 and other literature sources should be consulted for additional applications information.