Thermodynamic Quantities

Laboratory and Industrial-Grade Thermometers

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Technical Contact:
C. Dawn Cross
Tel: 301/975-4822
E-mail: dawn.cross@nist.gov

Please contact the technical staff before shipping instruments or standards to the address listed below.

Mailing Address:
National Institute of Standards and Technology
100 Bureau Dr., Stop 8363
Gaithersburg, MD 20899-8363

NOTE: The minimum number of test points per thermometer is two. Fahrenheit ranges are not direct conversions of the Celsius ranges. 

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Laboratory Thermometers (31010C-31100C)

This service provides for the calibration of a variety of thermometers covering the range from -196 °C to +550 °C (-321 °F to +1022 °F). Thermometers belonging to the large and varied group which may be classified as laboratory, or "chemical," thermometers are regularly accepted. These are of the liquid-in-glass type with either solid-stem or enclosed scale. Ordinary household or meteorological thermometers will not, in general, be accepted unless the scale is graduated on the glass stem itself and the thermometer can be readily detached from its mounting for insertion in a liquid bath. Every thermometer submitted must be uniquely identified by a serial number and must pass a preliminary examination for fineness and uniformity of graduation; for cleanliness of the mercury and the capillary bore; for freedom from moisture, gas bubbles, and cracks in the glass; for adequacy or omission of gas filling where needed; for insufficient annealing; and, for misnumbered graduations. When these or other serious defects are found, the thermometer is returned untested.

The thermometers to be calibrated are placed in a constant temperature bath along with a NIST-calibrated standard platinum resistance thermometer (SPRT). The SPRT maintains calibrations traceable to the International Temperature Scale of 1990 (ITS-90), with a maximum expanded uncertainty of 0.7 mK. (See Table 6.2)

Table 6.2. Calibration Uncertainties for Total Immersion Thermometers

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Special Tests of Thermometers (31110S-31150S)

Special tests may be conducted on temperature-measuring devices such as industrial grade platinum resistance thermometers, digital thermometers, and thermistors. Laboratory personnel should be consulted before submitting items.

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References-Laboratory and Industrial-Grade Thermometers

ASTM Standard E 1, Standard Specification for ASTM Thermometers, Annual Book of ASTM Standards 14.03, p. 1, Amer. Soc. for Test. And Matls., Philadelphia, PA (1996).

ASTM Standard E 77, Standard Test Method for Inspection and Verification of Thermometers, Annual Book of ASTM Standards 14.03, p.61, Amer. Soc. for Test. and Matls., Philadelphia, PA (1996).

A Procedure for the Effective Recalibration of Liquid-in-Glass Thermometers , J. A. Wise, Natl. Inst. Stand. Technol. Spec. Publ. 819 (Aug. 1991).

Assessment of Uncertainties of Liquid-in-Glass Thermometer Calibrations at the National Institute of Standards and Technology, J. A. Wise, NISTIR 5341 (Jan. 1994).

The International Temperature Scale of 1990 (ITS-90), H. Preston-Thomas, Metrologia 27, 3-10 (1990); Metrologia 27, 107 (1990).

NIST Measurement Services: Liquid-in-Glass Thermometer Calibration Service , J. A. Wise, Natl. Inst. Stand. Technol. Spec. Publ. 250-23 (Sept.1988).

Thermometer Calibration: A Model for State Calibration Laboratories, J. A. Wise, and R. J. Soulen, Natl. Bur. Stand. (U.S.), Monogr. 174 (Jan.1986).

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