Density Changes in Thermometer Glasses

Abstract

A study was made of the density changes in the thermometer glasses, Corning 0041, 7560, 1720 and an experimental glass, Corning EXP175EK.Thermometers fabricated from these glasses were given similar heat-treatments in their respective annealing ranges. Measurements were then made of the ice point changes at various fixed temperatures from room temperature to the normal upper useful limits of the glasses. Holding periods extended to 1 year. The ice point change in a thermometer is a measure of the per cent density change in the glass from which the bulb is fabricated. The relation of this change in density to temperature for a given duration of roasting appears to be well represented by two curves of the form of a constant times a temperature to a power. The value of the power appears to change rather abruptly at some temperature, To, in the neighborhood of 150OC. below the strain point temperature and to be constant in the regions on either side of TO.At equal temperatures below the strain point the behavior of the glasses is quite similar.

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

“…The changes in volume of LiG thermometer bulbs came under detailed examination in the mid-19th century and continued well into the 20th [94,[117][118][119][120][121][122][123][124][125][126][127]. Starting in April 1844, James Joule began an ice-point drift experiment using a long high-resolution Dancer Hg-LiG Fahrenheit thermometer that had been manufactured a few months earlier.…”

Thermometer calibration :

“…Some types of glasses commonly used in the manufacture of thermometer bulbs and reasonable upper temperature limits are estimated by Thompson [12] in table 13. Thompson's estimates are based upon the work of Liberatore and Whitcome [13]. The results show that significant changes in bulb volume may occur if the bulb is heated for long periods of time at temperatures higher than 130 °C (234 °F) below the strain point of the bulb glass.…”

“…the time of exposure to the high temperature, and the rate of cooling. Evidence from many investigations [13,15,16] seems to indicate that when a glass is held indefinitely at some fixed temperature, density (and volume) changes proceed toward a preferred density corresponding to a quasi equilibrium condition characteristic of the particular kind of glass and the temperature.…”

Calibration of liquid-in-glass thermometers

“…Thus, when during use the correction at the ice point is found to be higher (or [5,6]. This is conveniently carried out with a faden thermometer ("thread figure 8(a) These estimates by Thompson [8] are based upon the work of Liberatore and Whitcomb [9] All high-temperature thermometers should be filled with a dry inert gas under sufficient pressure to prevent separation of the mercury at any temperature for which the scale is graduated. Total-immersion thermometers graduated above 150°C or 300°F must be gas fSled to minimize the distillation of mercury from the top of the column.…”

“…Gas filling for lower temperatures is optional, but is strongly recommended. Evidence from many investigations [9,11,12] [14].…”