Expansion measurements, checking

Some remarks are made about the conception and the automation of volumetric devices for the determination of gets adsorption isotherms. The calibration problems discussed concern a procedure to check the manometer linearity the optimal pressure ratio for the calibration of volumes by gas expansion measurements of He adsorption in zeolites minimal measurable surface area. The possibility of readily setting experimentai points in a prescribed zone of the isotherm by using operating iines is discussed, and ruies for the extrapolation of the isotherms are suggested for some cases a modified BET equation for adsorption in micro/mesoporous solids, and a relation between the saturation volume and the capillary condensation pressure. 

Method (x) allows the dew point to be corrected for pressure. The basis is that the mole fraction y = p/P is the same for a given mixture composition at all values of total pressure P. In particular, the dew point measured in a compressed air duct can be converted to the dew point at atmospheric pressure, from which the humidity can be calculated. It is necessary to check that the temperature change associated with compression or expansion does not bring the dry-bulb temperature to a point where condensation can occur. Also, at these elevated pressures, it is strongly advisable to apply the enhancement factor (see BS 1339). 

The shape of the bed expansion curve can be used as an indicator of the likely behaviour of a group A powder (see section 3.2) and the ratios of bed heights at wMB and wMF are uniquely related to the ratio of the velocities. The measurement of bed expansion is, therefore, a useful check on the velocity ratio. 

We present here only one example of experimentally measured nucleation rates, those for n-butanol. Viisanen and Strey (1994) measured homogeneous nucleation rates of n-butanol in argon in an expansion chamber as a function of saturation ratio in the temperature range 225 to 265 K. In this temperature range the equilibrium vapor pressure and surface tension of n-butanol are known with sufficient accuracy that a quantitative comparison of the observed nucleation rates with those predicted by classical theory could be performed. Figure 10.7 shows the measured nucleation rates (the data points) and the predictions of the classical theory (solid lines). Nucleation rates ranging from about 10 to 10 cm s were measured. To check for possible influence of the carrier gas, measurements were also carried out with helium and xenon as carrier gases. The authors did not ob-... 

Duske [7] also discussed several other techniques of value for this material. DSC can be used to check the oxidation resistance of the wire insulation by determination of the oxidation induction time (OFT) — an isothermal technique to determine when the oxidation will occur. Thermogravimetry (TG) has also been used to examine the decomposition of the insulation and the effectiveness of flame retardants. TMA is also useful for measuring the diermal expansion of the wire insulation and this technique is also applicable to multi-layered coatings. 

The target point of the capacity expansion was set at 30,000 t-zinc annually, with minimum investment. At first, we checked bottle necks at each process, when all the equipment was in full action. Then we examined measures to increase the operation of every piece of equipment up to the maximum. Mainly, gas handling in the roasting process, iron removal capacity in the hematite process, rectifiers for zinc electrolysis, cooling capacity for the electrolyte, and a transformer at the main transforming station, were considered. 

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