Pressure, absolute wire

Vacuum pump capable of maintaining a pressure (absolute) of at least 5mm of mercury 3.S Wire holders for solution tubes (Fig Et 7)... 

Another example of a reaction nearly independent of pressure in this way is the catalytic decomposition of hydrogen iodide on the surface of a heated gold wire. X The initial pressure of the gas can be varied from 100 mm. to 400 mm. with a resulting change in the absolute rate of reaction which amounts to about 45% only instead of 400%. 

The vibrating cylinder version of this type of transducer employs a sensing element of the straight tube type and is similar to the vibrating cylinder density meter (Section 6.6.1). The cylinder is maintained in oscillation by a feedback amplifier/limiter combination and its frequency of oscillation varies with the pressure of the fluid within it, which alters the hoop stress on the cylinder. As with the vibrating wire, the frequency of oscillation increases with the fluid pressure. In order to be able to use the sensor for the measurement of absolute pressures, it is surrounded with a cylindrical housing and the annular space between the two is evacuated. Such sensors give excellent repeatability and have a relatively low temperature sensitivity. 

Preparation. (1) 3.5 g. of lithium metal (0.5 g. atom) and absolute ethanol (0.5 mole) are added to 500 ml. of benzene under nitrogen, and when the reaction is complete the benzene is removed by distillation, and lithium ethoxide is obtained as a white solid. (2) Lithium wire (3.5 g.) is added to 100 ml. of absolute ethanol under reflux, and when the initial reaction has subsided, the mixture is refluxed for 8 hrs. Evaporation under reduced pressure gives 42 g. of a white solid presumed to be LiOCzHs C HjOH (theory 46 g.). (3) A 0.2M solution is prepared by dissolving 1.40 g. of lithium wire in 1 I. of absolute ethanol. 

For a fluid at rest with both sides exposed to the same pressure, Eq. 17.11 indicates that [l// i +1/ 2] nu st be zero. This is obviously true of a plane surface, but it is also true of many complicated surfaces, such as that shown in Fig. 17.10. This is the shape taken by an open-ended soap film attached to two circular wire loops. Here the center of curvature in the xy plane is on the z axis, and the center of curvature in the xz plane is outside the film. Since these are on opposite sides of the film, R and R have opposite signs. To make [1/7 , + I/R2] equal zero, we must make them have the same absolute value we can show (Prob. 17.10) that this is the description of a catenoid curve. 

The temperature distribution in the loop is measured with chromel-alumel thermocouples and two Pt-100 temperature sensors for reference measurements. Absolute pressure is measured at the top of the riser and at the inlet of the core. The liquid level in the steam dome is measured with a differential pressure sensor. The differential pressure over the friction settings of the individual channels is a measure for the flow distribution over the coolant channels and bypass channels. The total flow in the loop is measured at 2 different positions with electromagnetic flow meters. The void fraction at a given height can be measured with gamma transmission techniques. At a fixed height at the top of the riser the radial void distribution is measured with a wire-mesh sensor, which measures the conduction of the two-phase mixture on a two-dimensional grid. Furthermore, laser doppler anemometry is used to study the local liquid velocity in the core or in the riser. 

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