Bubble-through measurement

While simple mechanical fiHing-level meters such as dipsticks and inspection glasses are reliable and accurate, they are not suitable for transmitting measured values. A cheap and reliable method is bubble-through measurement (Figure 2.8-4), which in principle measures the hydrostatic pressure and thus transforms the measurement of level into the measurement of pressure difference, which can readily be... 

Breath alcohol testing is accompHshed by a number of techniques. The oldest rehable procedure involves bubbling a measured volume of deep-lung air containing alcohol through an acidic solution of potassium dichromate, Deep-lung air is the last portion of expired breath. It is collected in... 

Gas streams can be analy2ed for ammonia by bubbling a measured quantity of the gas through a boric acid solution to absorb the ammonia. The solution is then titrated against sulfuric acid. This analysis is applicable only if other constituents in the gas stream do not react with boric acid. 

Viscosity can also be determined from the rising rate of an air bubble through a Hquid. This simple technique is widely used for routine viscosity measurements of Newtonian fluids. A bubble tube viscometer consists of a glass tube of a certain size to which Hquid is added until a small air space remains at the top. The tube is then capped. When it is inverted, the air bubble rises through the Hquid. The rise time in seconds may be taken as a measure of viscosity, or an approximate viscosity in mm /s may be calculated from it. In an older method that is commonly used, the rate of rise is matched to that of a member of a series of standards, eg, with that of the Gardner-Holdt bubble tubes. Unfortunately, this technique employs a nonlinear scale of letter designations and may be difficult to interpret. 

Precipitated Calcium Carbonate. Precipitated calcium carbonate can be produced by several methods but only the carbonation process is commercially used in the United States. Limestone is calcined in a kiln to obtain carbon dioxide and quicklime. The quicklime is mixed with water to produce a milk-of-lime. Dry hydrated lime can also be used as a feedstock. Carbon dioxide gas is bubbled through the milk-of-lime in a reactor known as a carbonator. Gassing continues until the calcium hydroxide has been converted to the carbonate. The end point can be monitored chemically or by pH measurements. Reaction conditions determine the type of crystal, the size of particles, and the size distribution produced. 

In the MBP method, an inert gas passes through a precision bore capillary of radius r which then creates a gas bubble at the tip. The pressure within the bubble is measured and the maximum pressure P(m) in g/cm2 is related to the surface tension y in dyne/cm by means of... 

Several other methods have been employed to access the conditions of bubble collapse. Misik et al. studied H20—D20 mixtures and through measurements with the use of spin traps, were able to determine the temperature from the relative rates of O—H and O—D cleavage [21]. They reported temperatures ranging from 2,000 to 4,000 K. Hart et al. developed a method based on the gas phase recombination of methyl radicals (MRR method), formed from the decomposition of methane [22]. They calculated temperatures of 2,000-2,800 K depending on the methane concentration. 

Figure 2 shows the essential parts of such an arrangement. There is a (smaller) cell with provisions for measurement of pH, titration, stirring with an inert stirrer, and gas bubbling through the solution. When the solution in this cell has been titrated to the selected pH value, a peristaltic pump takes the solution to the inlet of the flow cell. Before the solution comes to the metal electrode, it passes two thin holes in the bottom of the... 

Figure 3. Long-term corrosion measurement of an electrolytic Sn-Zn alloy containing 26% Zn (by weight) in a 3% NaCI solution, pH = 4.000, with argon bubbling through the solution. Upper diagram corrosion potential vs. time lower diagram CMT and EC measurements vs. time. After 80-100 min, the ratio CMT/BC is close to 4. (Reprinted from Ref. 2, with kind permission from Elsevier Science Ltd., Kidlington, Oxfmd, UK.)...

Experiment 3. Rates of Formation of Ethylenediamine and Ammonia vs. Rate of Disappearance of Cobalt (II). Carbon dioxide-free air was bubbled through the solution. Ammonia, ethylenediamine, and cobalt (II) were determined periodically over a total reaction time of 5 hours. The results of this experiment are collected in Table I and plotted in Figure 3. The ammonia measured was actually the ammonia volatilized during the reaction, but it was calculated as moles per liter of solution in order to be consistent with the ethylenediamine and cobalt (II) results. 

This method can be used for the determination of the ozone concentration in the gas and/or liquid phase. The measurement takes place in the liquid phase, though, so that to measure a process gas containing ozone, the gas must first be bubbled through a flask containing potassium iodide KI. For the measurement of the liquid ozone concentration, a water sample is mixed with a KI solution. The iodide F is oxidized by ozone. The reaction product iodine 12 is titrated immediately with sodium thiosulfate Na2S203 to a pale yellow color. With a starch indicator the endpoint of titration can be intensified (deep blue). The ozone concentration can be calculated by the consumption of Na2S203. 

A sample is heated, usually at or above 100°C, while air is bubbled through it, and the volatiles created are transferred to a water trap where conductivity is measured (Fig. D2.3.1). The induction period endpoint is determined by the time it takes for the sample to begin a rapid increase in conductivity. The time required for the sample to reach its induction period endpoint is termed the Oil Stability Index (OSI). The Oil Stability Index is Official Method Cd 12b-92 of the American Oil Chemists Society (AOCS, 1996). 

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