Gases using

This is the most difficult part of setting up a discharge because the discharge gases used are largely insulating and, theoretically, there are no electrons to start a current flow between the electrodes. However, there are sources of electrons and ions, some natural and some artificial ... 

Gases used in the manufacture of semiconductor materials fall into three principal areas the inert gases, used to shield the manufacturing processes and prevent impurities from entering the source gases, used to supply the molecules and atoms that stay behind and contribute to the final product, and the reactive gases, used to modify the electronic materials without actually contributing atoms or molecules. 

Table 5. Thermal Conductivity at 20°C of Gases Used in Cellular Polymers ...

High Pressure in the Chemical Industry. The use of high pressure in industry may be traced to early efforts to Hquefy the so-called permanent gases using a combination of pressure and low temperature. At about the same time the chemical industry was becoming involved in high pressure processes. The discovery of mauveine in 1856 led to the development of the synthetic dye industry which was well estabUshed, particularly in Germany, by the end of the century. Some of the intermediate compounds required for the production of dyes were produced, in autoclaves, at pressures of 5-8 MPa (725-1160 psi). 

The gases used in the CVD reactor may be either commercially available gases in tanks, such as Ar, N2, WF, SiH, B2H, H2, and NH Hquids such as chlorides and carbonyls or soflds such as Mo carbonyl, which has a vapor pressure of 10 Pa (75 mtorr) at 20°C and decomposes at >150° C. Vapor may also come from reactive-bed sources where a flowing haUde, such as chlorine, reacts with a hot-bed material, such as chromium or tantalum, to give a gaseous species. 

Chapman and Enskog (see Chapman and Cowling, 1951) made a semi-empirical study of tire physical properties of gases using the Lennard-Jones... 

The methods that have been discussed require specially designed instruments. Laboratories without such instruments can measure these gases using general-purpose chemical analytical equipment. A compendium of methods for these laboratories is the "Manual on Methods of Air Sampling and Analysis"published by the American Public Health Association. (10). 

This is a low value, therefore, the possibility exists of an up-rate relative to any nozzle flow limits. At this point, a comment or two is in order. There is a rule of thumb that sets inlet nozzle velocity limit at approximately 100 fps. But because the gases used in the examples have relatively high acoustic velocities, they will help illustrate how this limit may be extended. Regardless of the method being used to extend the velocity, a value of 150 fps should be considered maximum. When the sonic velocity of a gas is relatively low, the method used in this example may dictate a velocity for the inlet nozzle of less than 100 fps. The pressure drop due to velocity head loss of the original design is calculated as follows ... 

Every gas has a critical temperature above which it cannot be liquefied by application of pressure alone (Chapter 4). As a result, gases used, e.g., as an inert medium to reduce oxygen content of atmospheres containing flammable gas or vapour (Chapter 6) are often shipped and stored as cryogenic liquid for convenience and economy. 

Absorption, in which a liquid solvent is used to remove certain compounds from a gas by virtue of their preferential solubility. Examples of absorption involve desulfurization of flue gases using alkaline solutions or ethanolamines,... 

Table 9.4 indicates some of the factors that have to be considered when dealing with the moisture content in air. In the case of inert gases used in various industrial processes, other factors have to be considered. 

Katharometer A device that compares the thermal conductivity of two gases, used to detect the presence of impurities in air. 

Tracer gases Gases used with an instrument to determine the air change rate within a space. 

Contained gases used were hydrogen (H2), air, argon (Ar), helium (He), or... 

Table 21.7.2 smnmarizes die results of applicadon of a preliminary liazard analysis (PHA) to the pyrolysis section of an ediylene plant. The major liazard to the persomiel and plant is die fire or explosion hazard of die gases used or produced in die process. 

Simplify the relation for heating and cooling gases, using... 

Figure 10-53B. Determine the inside heat transfer coefficient of common gases (Used by permission Ganapathy, V. Hydrocarbon Processing, Sept. 1977. Gulf Publishing Company, Houston, Texas. All rights reserved.)...

Determine the tube-side film coefficient for water, using Figure 10-50A or 10-50B. For other liquids and gases, use Figure 10-46. Correct hj to the outside tube surface by... 

Figure 12-72. Sonic velocity of common gases. (Used by permission Koenig, C. F. III. Refining Engineer, Aug. 1958. Hart Publications, Inc. All rights reserved.)...

Figure 12-123B-1. Speciai biade construction for handiing dirty gases. (Used by permission Bui. C-5200. The Howden Fan Co.)...

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