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Vapor Pressure Thermometry Thermometers

A descriptive flowchart has been prepared by Sparks (Materials at Low Temperatures, ASM, Metal Park, OH, 1983) to show the temperature range of cryogenic thermometers in general use today. Parese and Molinar (Modem Gas-Based Temperature and Pressure Measurements, Plenum, New York, 1992) provide details on gas- and vapor-pressure thermometry at these temperatures. [Pg.959]

Vapor Pressure Thermometry. The pressure exerted by a saturated vapor in equilibrium with its liquid is a very definite function of temperature, and can be used to measure the temperature of the liquid. A number of useful fixed points for several cryogenic fluids are given in Table 8.3. With a good pressure-measuring device, the vapor pressure thermometer is an excellent secondary standard since its temperature response depends upon a physical property of a pure compound or element. Many expressions have been... [Pg.522]

Most thermometry using the KTTS direcdy requites a thermodynamic instmment for interpolation. The vapor pressure of an ideal gas is a thermodynamic function, and a common device for reali2ing the KTTS is the helium gas thermometer. The transfer function of this thermometer may be chosen as the change in pressure with change in temperature at constant volume, or the change in volume with change in temperature at constant pressure. It is easier to measure pressure accurately than volume thus, constant volume gas thermometry is the usual choice (see Pressure measurement). [Pg.396]

The ITS-90 has its lowest point at 0.65 K and extends upward without specified limit. A number of values assigned to fixed points differ from those of the immediately previous scale, IPTS-68. In addition, the standard platinum resistance thermometer (SPRC) is specified as the interpolation standard from 13.8033 K to 961.78°C, and the interpolation standard above 961.78°C is a radiation thermometer based on Planck s radiation law. Between 0.65 and 13.8033 K interpolation of the scale rehes upon vapor pressure and constant-volume gas thermometry. The standard thermocouple, which in previous scales had a range between the upper end of the SPRT range and the lower end of the radiation thermometer range, has been deleted. [Pg.399]

The ITS-90 scale extends from 0.65 K to the highest temperature measurable with the Planck radiation law (—6000 K). Several defining ranges and subranges are used, and some of these overlap. Below —25 K, the measurements are based on vapor pressure or gas thermometry. Between 13.8 K and 1235 K, Tg is determined with a platinum resistance thermometer, and this is by far the most important standard thermometer used in physical chemistry. Above 1235 K, an optical pyrometer is the standard measrrremerrt instmment. The procedtrres used for different ranges are sttmmarized below. [Pg.558]

A special case of constant-volume gas thermometry is that based on the vapor pressure of a liquid. As the temperature of a solvent is increased, its vapor pressure increases proportionately over a wide range of conditions. The temperature range is Umited to temperatures between the boiling point and freezing point of the solvent and it must also be lower than the critical point of the fluid. These thermometers are easy to adapt to common experimental equipment. [Pg.160]

In the last few years a program of precision secondary thermometry in the 2-4 K range has been greatly facilitated by the use of metallic storage dewars which contain a few liters of liquid helium. The temperature distribution in these nearly "constant temperature" baths have been explored with both resistance and vapor-pressure thermometers. The results of these investigations, and also the reproducibilities of resistance thermometers, are presented. [Pg.542]

Vapor pressure and gas thermometry offer sensitive methods of temperature measurement with the advantage that no calibration is necessary. Further advantages are that these transducers are not sensitive to magnetic fields or electric fields. In the case of vapor pressure thermometers, the time response may be made comparable to the resistance thermometers. [Pg.546]


See other pages where Vapor Pressure Thermometry Thermometers is mentioned: [Pg.25]    [Pg.25]    [Pg.25]    [Pg.21]    [Pg.41]    [Pg.28]    [Pg.31]    [Pg.40]    [Pg.25]    [Pg.523]   
See also in sourсe #XX -- [ Pg.2 , Pg.4 , Pg.6 , Pg.542 ]




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