Pressure quartz spiral gauge

G. Bourdon Gauges. As an alternative to mercury manometers there is a variety of gauges based on mechanical or electrical pressure transducers. This section presents a description of purely mechanical gauges which still find use in this electronic age.4 The metal Bourdon gauge (Fig. 7.5) is fashioned around a semicircular thin-walled metal tube with mechanical linkage to a pointer. Fused-quartz spiral gauges are also available. In this case, a thin spiral is sensitive to a pressure differential, and the deflection is balanced with air pressure in the surrounding envelope. The air pressure is then measured with a manometer. 

Vapor Pressure Measurements. Total vapor pressures were measured at 30°C with a Texas Instruments quartz spiral gauge. The procedure used was similar to that given previously (5). The concentration of water after the experiment was checked by Karl Fischer titration, while that of ether was found by weighing the cell before and after the vapor pressure determination the loss of weight was that of ether. Since Sb( V) interferes with the Karl Fischer titration of water, the water concentration in the HSbClG solutions was also obtained from the loss of weight of the cell. 

The two small needle valves I, integral with the lid, are used to control the flow of liquid from the pressurized injectors into the cell. The pressure is measured with a quartz spiral gauge thermostatted at 322 K. The connecting line J is heated to a temperature above the bath temperature to prevent condensation. With... 

The spiral gauge consists of a hollow spiral of very thin glass or quartz fixed at the end at which it is connected to the vacuum line, the other end being closed. Changes in the difference between inside and outside pressure lead to expansion or contraction of the spiral. The resulting movement can be magnified by a mechanical or optical lever. 

Sullivan has carried out a very interesting study of the room temperature photo-induced reaction of Bt2 and H2. The photolysis of Br2 at 5780 A forms two ground-state bromine atoms which react with hydrogen to form HBr. Sullivan measured the absorbed intensity with a calibrated solar cell and the amount of HBr produced with a quartz-spiral pressure gauge. In experiments at 0 and 25 °C he found the rate of HBr production to be directly proportional to the absorbed light intensity. Furthermore, the temperature dependence of the rate corresponded to an activation energy of 0 kcal.mole . Finally, the rates of HBr formation at both 0 and 25 °C are faster by a factor of more than 200 than can be accounted for by the reaction... 

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