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Thermocouple Calibration Services Calibration services for all commonly used types of thermocouples and thermocouple materials are provided by NIST from -196 ºC to +2100 ºC. The temperature range for a particular calibration depends on the type of wire or thermocouple submitted. The thermocouples are calibrated by one or more of three general methods, depending on the type of thermocouple, the temperature range, and the accuracy required. All three methods provide traceability to the International Temperature Scale of 1990 (ITS-90). In the first method, thermocouples are calibrated by comparison with a reference thermocouple maintained at NIST. In the second method, thermocouples are calibrated against a standard platinum resistance thermometer (SPRT). In the third method, thermocouples are calibrated at four defining temperatures of the ITS-90: the freezing points of zinc, aluminum, silver, and gold. Single-leg thermoelements are tested against the NIST maintained platinum thermoelectric reference standard, Pt-67, by the first or second method. Thermocouple and thermoelement calibrations below 0 ºC are made in a cryostat; those above 0 ºC are made in stirred liquid baths, metal freezing-point cells, or electric tube-type furnaces. Vacuum or inert-gas furnaces are also available if needed. Calibration tables giving values of the thermocouple emf at 1 degree intervals are provided for B, S, R, and T types of thermocouples. Current fees, the temperature ranges, and calibration uncertainties for standard letter-designated thermocouples calibrated by the three methods described above are given in the NIST Calibration Services User Guide. While over 90% of the thermocouples calibrated at NIST are letter-designated types, calibration services are also provided to temperatures as high as 2100 ºC for nonstandard types of thermocouples formed from various W-Re, Ir-Rh, and Pt-Rh alloys. Calibrations for the non-standard types are performed as special tests on an actual cost basis, and the temperature ranges and calibration uncertainties depend on the thermocouple type. Only bare wires are needed for NIST thermocouple calibrations. We would prefer customers not to send ceramic insulating and protecting tubes since they may get broken during shipment. If the thermocouple is shipped in a mount such as a protection tube assembly, a special dismantling fee may be charged and the parts will be returned unassembled. All thermocouple calibration data furnished in reports are based on a reference junction temperature of 0 ºC (32 °F). The customer may request that calibration results be given either in degrees Celsius or Fahrenheit. For base-metal thermocouples (types E, J, K, N, and T) and thermocouple materials, only those that are unused will be accepted for test. A calibration will be undertaken only if the thermocouple is likely to yield the specified accuracy. Information about the NIST thermocouple calibration services and the requirements for thermocouples to be submitted for special tests may be obtained by contacting: Christopher Meyer or Karen Garrity Inquiries about thermocouple calibrations performed by comparison with a standard platinum resistance thermometer should be directed to:
Shipment of thermocouples for calibration should be made to the above address. Shipping costs are paid by the customer. NIST assumes no responsibility for damage in shipment. A formal purchase order for the calibration or test should be sent to NIST at or before the time the thermocouple material is shipped. The purchase order should provide: 1. Clear identification of the types of thermocouple materials submitted; 2. The calibration procedure to be followed; 3. The name and telephone number of the person responsible for the procurement; 4. The name and telephone number of a technical contact familiar with the calibration request; and 5. Instructions for return shipment including the shipping and billing addresses and the customer's choice of carrier. References on Thermocouples 1. Manual on the Use of Thermocouples in Temperature Measurement. ASTM manual series: MNL-12; 1993, 290 p. 2. Burns, G. W.; Scroger, M. G.; Strouse, G. F.; Croarkin, M. C.; Guthrie, W. F., Temperature- Electromotive Force Reference Functions and Tables for the Letter-Designated Thermocouple Types Based on the ITS-90. Nat. Inst. Stand. Technol. Monograph 175; 1993. 630 p. 3. Burns, G. W.; Scroger, M. G., The Calibration of Thermocouples and Thermocouple Materials. Nat. Inst. Stand. Technol. Special Publication 250-35; 1989. 200 p. 4. Ripple, D.; Burns, G. B.; Scroger, M. G., Assessment of Uncertainties of Thermocouple Calibrations at NIST. Nat. Inst. Stand. Technol. NISTIR 5340; 1994. 34 p. 5. Ripple, D.; Young, S., NIST ITS-90 Thermocouple Database. Nat. Inst. Stand. Technol. Standard Reference Database 60; 1995. Diskette and manual, 56 p. Contact Andrea Swiger to obtain copies of the references. |
Last Updated on: 2/25/04
| Contacts Tests and Fees Calibration Uncertainties Industrial Thermometers Low Temperature SPRTs Thermocouples |
| Bibliography Fixed Points Humidity IPRTs ITS 90 Liquid in Glass Meas. Assurance Publications RTP SPRTs SRMs Tempmeko 2001 Thermistors Thermocouples Thermodynamic |
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Precision Themometry Workshop: ITS 90 Fixed Point Cell Mini Workshop: Liquid In
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Calibration for RTP |
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