NIST Calibration Uncertainties of Liquid-in-Glass Thermometers over the Range from −20 °C to 400 °C

Vaughn, C D.; Strouse, Gregory F.

doi:10.1063/1.1627166

Cited by 7 publications

(6 citation statements)

References 6 publications

(10 reference statements)

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“…LiG Thermometers: Resolution, Linearity, and Joule-Drift 3.1.1. Resolution Until relatively recently, the U.S. National Institute of Standards and Technology (NIST) carried out detailed calibrations and evaluations of LiG thermometers [99,100]. NIST publications list the visually indistinct physical imperfections that can degrade the accuracy of a LiG thermometer, including "changes in bulb volume, microscopic alterations in glass geometry at elevated temperature, microscopic cracking, degradation of the thermometer liquid", and endogenous solids, such as glass particles in the capillary [101,102].…”

Section: Resultsmentioning

confidence: 99%

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LiG Metrology, Correlated Error, and the Integrity of the Global Surface Air-Temperature Record

Frank

2023

Sensors

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The published 95% uncertainty of the global surface air-temperature anomaly (GSATA) record through 1980 is impossibly less than the 2σ = ±0.25 °C lower limit of laboratory resolution of 1 °C/division liquid-in-glass (LiG) thermometers. The ~0.7 °C/century Joule-drift of lead- and soft-glass thermometer bulbs renders unreliable the entire historical air-temperature record through the 19th century. A circa 1900 Baudin meteorological spirit thermometer bulb exhibited intense Pb X-ray emission lines (10.55, 12.66, and 14.76 keV). Uncorrected LiG thermometer non-linearity leaves 1σ = ±0.27 °C uncertainty in land-surface air temperatures prior to 1981. The 2σ = ±0.43 °C from LiG resolution and non-linearity obscures most of the 20th century GSATA trend. Systematic sensor-measurement errors are highly pair-wise correlated, possibly across hundreds of km. Non-normal distributions of bucket and engine-intake difference SSTs disconfirm the assumption of random measurement error. Semivariogram analysis of ship SST measurements yields half the error difference mean, ±½Δε1,2, not the error mean. Transfer-function adjustment following a change of land station air-temperature sensor eliminates measurement independence and forward-propagates the antecedent uncertainty. LiG resolution limits, non-linearity, and sensor field calibrations yield GSATA mean ±2σ RMS uncertainties of, 1900–1945, ±1.7 °C; 1946–1980, ±2.1 °C; 1981–2004, ±2.0 °C; and 2005–2010, ±1.6 °C. Finally, the 20th century (1900–1999) GSATA, 0.74 ± 1.94 °C, does not convey any information about rate or magnitude of temperature change.

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Section: Resultsmentioning

confidence: 99%

“…After about year 2000, NIST calibration and testing of LiG thermometers utilized a computer-driven digital camera and 10× magnification to visualize the meniscus of the liquid column [100,103]. System resolution was 1/34 of the smallest stem division, equivalent to ±0.03 • C for a 1 • C/division LiG thermometer.…”

Section: Resultsmentioning

confidence: 99%

LiG Metrology, Correlated Error, and the Integrity of the Global Surface Air-Temperature Record

Frank

2023

Sensors

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“…As an alternative, values of s for mercury-filled thermometers may be estimated based on literature values of liquid-in-glass thermometer uncertainties [12] and on the resolution of various methods to read thermometers. Typical reading resolutions for various methods are listed in Table 2.…”

Section: Uncertainties With Correctionmentioning

confidence: 99%

“…From Ref. [12], values of s obtained with a video readout may be approximated as s = 0.02 °C for temperatures less than 100 °C, and s = 0.04 °C for temperatures between 100 °C and 200 °C. (For thermometers graduated in Fahrenheit, the equivalent values are s = 0.036 °F for temperatures less than 212 °F, and s = 0.072 °F for temperatures between 212 °F and 392 °F.)…”

Section: Uncertainties With Correctionmentioning

confidence: 99%

Maintenance, validation, and recalibration of liquid-in-glass thermometers

Cross¹,

Miller²,

Ripple³

et al. 2009

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Liquid-in-glass thermometers are pervasive throughout industry. These thermometers provide a convenient method for measuring temperature over a broad range of applications with reasonable stability and accuracy. However, like all thermometers, liquid-in-glass thermometers are subject to drift as a function of time and maximum temperature of use. This paper describes methods for the validation and recalibration of previously calibrated liquid-in-glass thermometers to maintain the metrological traceability established with the initial calibration. Procedures and examples are given for visually inspecting a thermometer, using an ice point for a single-point recalibration, and determining uncertainties for thermometers with a single-point recalibration. We discuss when a single-point recalibration is acceptable, and when a full recalibration is needed.

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“…Optimal uncertainties achievable for the calibration of a LiG thermometer are discussed in Ref. [11]. On the other hand, use for extended periods of time at high temperature may cause drift of the LiG thermometer outside the original manufacturer's tolerance, if not corrected by later recalibration.…”

Section: Comparison Of Uncertaintymentioning

confidence: 99%

Selection of Alternatives to Liquid-in-Glass Thermometers

Dean¹,

Ripple

Strouse

2005

Journal of ASTM International

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A desire to increase automation or to eliminate the use of mercury has prompted several ASTM committees to consider alternatives to ASTM Liquid-in-Glass (LiG) thermometers. In this paper, we address the technical issues of choosing an alternative. We first discuss the basic properties and relative merits of platinum resistance thermometers, thermistors, and thermocouples in the context of replacements for LiG thermometers; then list uncertainty components for measurements with alternative thermometers; and finally discuss other factors in temperature measurement and control that are important in the development and execution of ASTM standards.

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NIST Calibration Uncertainties of Liquid-in-Glass Thermometers over the Range from −20 °C to 400 °C

Cited by 7 publications

References 6 publications

LiG Metrology, Correlated Error, and the Integrity of the Global Surface Air-Temperature Record

LiG Metrology, Correlated Error, and the Integrity of the Global Surface Air-Temperature Record

Maintenance, validation, and recalibration of liquid-in-glass thermometers

Selection of Alternatives to Liquid-in-Glass Thermometers

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