Quartz thermometer

The calorimetric thermometer measures temperature changes within the calorimeter bucket. It must be able to provide excellent resolution and repeatability. High single-point accuracy is not required since it is the change in temperature that is important in fuel calorimetry. Mercurial thermometers, platinum resistance thermometers, quartz oscillators, and thermistor systems have all been successfully used as calorimelric thermometers. 

In a resonant-frequency thermometer, the resonance frequency of the medium serves as the temperature indicator. Included in this category are nuclear quadrupole resonance thermometers, quartz thermometers, and ultrasonic thermometers. These thermometers usually... 

Fig. 3. Metal freezing-point ceU A, pure graphite crucible B, thermometer weU C, highly pure metal and D, quartz envelope.

Groendes and Mesler (1982) studied the saturated film boiling impacts of a 4.7 mm water droplet on a quartz surface of 460 °C. The fluctuation of the surface temperature was detected using a fast-response thermometer. The maximal temperature drop of the solid surface during a droplet impact was reported to be about 20 °C. Considering the lower thermal diffusivity of quartz, this temperature drop implies a low heat-transfer rate on the surface. Biance et al. (2003) studied the steady-state evaporation of the water droplet on a superheated surface and found that for the nonwetting contact condition, the droplet size cannot exceed the capillary length. 

An industrial standard method has been developed to test the lightfastness of polymers in accelerated test equipment [103]. The apparatus consists of a quartz-xenon tube with a special optical filter between the light source and the specimen to produce light that resembles window glass-filtered daylight [104], Samples are mounted at a specific distance from the arc and are supported on a frame which revolves around the arc 1 to 5 times per minute for uniform exposure. A blower unit in the base provides a flow of air which makes it possible to maintain a black panel temperature of 45°C, measured by a black panel thermometer which is positioned at level with the samples. A black panel unit consists of a bimetallic thermometer mounted on a steel frame. Both faces of the frame plate and also the stem of the thermometer are coated with a heat-resistant glossy black enamel. The relative humidity level in the exposure cabinet is closely controlled. 

New types of thermometers include sensitive and reliable thermistors and quartz crystal thermometers. 

C, is a cylindrical glass vessel with a volume of 450 cm. The piezometer contains the solution and 330 gms of Hg. The top of the piezometer is fitted with a Taper joint for filling. A precision bore capillary, E, (2mm in diameter) is fitted to the bottom of the piezometer. The piezometer is suspended (6) in a brass or stainless steel pressure vessel, H. A glass boiler tube, J, encloses the upper portion of the capillary. The pressure vessel is filled with ethylene glycol which serves as a thermal and pressure medium. The entire apparatus is submerged in a constant temperature bath controlled to 0.001 C. The temperature inside the pressure vessel is monitored with a Hewlett-Packard quartz crystal thermometer (to determine when thermal equilibrium is reached after compression and decompression). 

Currie K. L. (1971). The reaction 3 cordierite = 2 garnet + 4 sillimanite + 5 quartz as a geological thermometer in the Ipinicon Lake Region, Ontario. Contrib. Mineral Petrol, 33 215-226. 

Several refractory accessory mineral thermometers have been applied, including aluminosilicate, magnetite, garnet and rutile in quartz-rich rocks and magnetite,... 

Clayton RN, Epstein S (1958) The relationship between 0/ 0 ratios in coexisting quartz, carbonate and iron oxides from various geological deposits. J Geol 66 352-373 Clayton RN, Kieffer SW (1991) Oxygen isotope thermometer calibrations. In Taylor HP, O Neil JR, Kaplan IR (eds.) Stable isotope geochemistry A tribute to Sam Epstein. Geochem Soc Spec Publ 3 3-10... 

Ultrasonic Thermometers. These are usually designed to respond to the temperature dependence of sound speed. In special cases where only one particular temperature is of interest, such as the temperature of a phase change, or the recrystallization temperature of a substance, the temperature dependence of attenuation may be utilized, Ultrasonic thermometers have found applications in the range —80 to +250 C, where the so-called quartz thermometer offers resolution of 0,1 millidegree and linear superiority to platinum resistance thermometers. 

For both type of microwave reactors, if the reactor is not supplied with a temperature sensor or more likely accurate temperature measurment is prerequisited during an experiment, the fiber-optic temperature sensor is directly applied to the reaction mixture. In order to secure the sensor from harsh chemicals, the sensor is inserted into a capillary that in turn is inserted into the reaction mixture. In such a case, it is strongly advocated to use capillaries that are made of quartz glass and are transparent to microwave irradiation. Any capillary that is made of glass or even borosilicate glass can always slightly absorb microwave energy, in particular, while the reaction mixture does not absorb microwaves efficiently, and in turn lead to failures of fiber-optic thermometer performance. 

Liquid in Glass Thermometers. Mercury-in-glass thermometers (or better yet, mercury-in quartz) function well between -25°C and 360°C their typical precision is 0.1 K. They must be corrected for (1) relatively small pressure effects and (2) a relatively large "exposed-stem correction," due to the different coefficients of thermal expansion of mercury and glass in the part of the thermometer not immersed in the system being measured. 

Quartz Crystal Thermometer. The temperature coefficient of the resonant frequency of quartz (14-20 MHz), using the piezoelectric effect, is a function of temperature (1 kHz per degree). In the temperature range -80°C to 230°C, an electronically controlled quartz crystal thermometer can be accurate to 0.02°C and has a sensitivity of 10 microdegrees centigrade in temperature difference measurements. 

A quartz crystal thermometer sustains a capacitance if the frequency of the RLC circuit is precisely tuned to 14 or 20 MHz (depending on the exposed crystal faces). The quartz crystal will then transmit a very precise frequency, which has a temperature coefficient (typically 1 kHz per degree centigrade). If the temperature fluctuations are precisely compensated by a feedback heater circuit, then a quartz crystal oscillator is precise to about 1 part in 1.4 x 108. 

Cuvettes Use 10-mm light-path fused quartz. Thermometer Use a partial immersion thermometer with a suitable range, graduated in 1/10°. 

Thermostat bath with a heater, adjustable thermoregulator, and stirrer thermometer with a resolution of at least 0.01 K (a platinum resistance thermometer, thermocouple or quartz thermometer could be used see Chapter XVII) illuminating light and cathetometer for reading the vertical position of the menisci number of sealed capillaries of uniform bore containing varying amounts of carbon dioxide, prepared in advance. 

In this section, the design and operation of familiar liquid thermometers, thermocouples, platinum resistance thermometers, thermistors, and optical pyrometers are discussed in detail. Briefer descriptions are also given of a variety of special thermometric devices such as quartz thermometers, germanium resistance thermometers, and sihcon-diode thermometers. 

Another attractive and widely used special thermometer is the quartz frequency thermometer, which is described in the next subsection, since it can be used over the very wide range from 4 K to 500 K. 

A modified version of the M-100 boiling point apparatus, made by the James F. Scanlon Co., Whittier, Calif, was used temperature was measured by a Hewlett-Packard model 2801A quartz thermometer. All measurements were made at atmospheric pressure with the temperature corrected then to 760 mm Hg. 

The elements of group Illb, gallium, indium, and thallium, are very rare and have small practical importance. Their principal compounds represent oxidation state - -8 thallium also forms thailous compounds, in which it has oxidation number - -1. Gallium is liquid from 29° C. its melting point, to 1700 C, its boiling point. It has found use as the liquid in quartz-tube thermometers, which can be used to above 1200° C. 

Tuttle OF (1949) The variable inversion temperature of quartz as a possible geologic thermometer. Am Mineral 34 723-730... 

Quartz glass thermometers filled with mercury under pressure have been constructed to measure temperatures up to 750 C. They are not used in this country, however, except to a negligible extent. Reports as to their behavior have not been promising. 

The thermometer is protected by a porcelain tube glazed on the outside, or by a quartz tube which fits into the terminal head. Por industrial use the refractory tube is itself protected by an outer metal tube. The metal tube is usually fitted to an extra terminal head through which the lead wires to the line are carried. On account of the deterioration of the platinum, thermometers constructed of fine wire are not very satisfactory for industrial use above 900°C. Heavy platinum wire, 0.6 mm. in diameter, may be employed up to 1,100°C. but the resistance of the thermometer is so low that it is necessary to use methods of measurement which do not depend upon constancy in the resistance of the lead wires, e.g. Thomson bridge or potentiometer. 

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