Gauge spiral

Both the Bourdon and spiral gauge can be used with a compensation method or with direct observation of the movement of the... 

C, static method-quartz spiral gauge, measured range -42.75 to 19.77°C, Lister 1941)... 

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. 

A few experiments made by Bircumshaw and Newman [5] at a temperature of 400°C in a spiral gauge apparatus agreed with the conclusion that the decomposition was quite different from that at the lower temperatures. There was no induction period, the whole of the reaction was a decelerating one, and decomposition went to completion. The reaction appeared to follow a simple power law, p = kf, where n varied with temperature and was always less than unity. 

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. 

Bourdon and spiral gauges with dial readout are available from Wallace Tiernan, 25 Main St., Belleville, NJ 07109. Warden quartz spiral gauges are available from Ruska Instrument Corp., Box 36010, Houston, TX 77036 Texas Instruments Inc., Display Systems, Box 1444, Houston, TX 77001. 

In the quartz spiral gauge, the semicircular metal tube is replaced by a quartz helix. 

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. 

Fig. 7. Mechanical gauges, (a) Spiral gauge (b) Bourdon spoon gauge (c) Click gauge.

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... 

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