Liquid across

For nonisothermal flow of liquids across tube bundles, the fric tion factor is increased if the liquid is being cooled and decreased if the liquid is being heated. The factors previously given for nonisotherm flow of liquids in pipes ( Tncompressible Flow in Pipes and Channels ) should be used. 

E/ig. Exp. Sta. Bull., 2 [1950]) recommend the following equations for pressure drop with laminar flow (Re, < 100) of liquids across banks of plain tubes with pitch ratios P/D( of 1.25 and 1..50 ... 

Packed columns must be provided with good initial distribution of liquid across the column cross section and redistribution of liquid at various height intei vals that decrease with increasing column diameter. A wide variety of distributors and redistributors are available. Packed columns should be considered when ... 

Effective area should not be confused with wetted area. While film flow of liquid across the packing surface is a contributor, effective area includes also contribiidons from rivulets, drippings, and gas bubbles. Because of this complex physical picture, effecdve interfacial area is difficnlt to measure directly. 

I. Hs - the static head, or the change in elevation of the liquid across the system. It is the difference in the liquid surface le el at the suction source or ve.s.sel, subtracted from the liquid surface level where the pump deposits the liejuid. The Hs is measured in feet of elevation change. Some systems do not have Hs or elevation... 

It is important to set close tolerances on the weir height, downcomer clearance, and plate flatness, to ensure an even flow of liquid across the plate. The tolerances specified will depend on the dimensions of the plate but will typically be about 3 mm. 

Inlet weirs, or recessed pans, are sometimes used to improve the distribution of liquid across the plate but are seldom needed with segmental downcomers. 

Substances that can potentially be taken up across the skin include gases and vapors, liquids and particulates. Liquids and substances in solution are taken up more readily than dry particulates. Dry particulates will have to dissolve into the surface moisture of the skin before uptake can begin. Absorption of volatile liquids across the skin may be limited by the rate at which the liquid evaporates off the skin surface. As a result of binding to skin components, the uptake of chemicals with the following groups can be slowed certain metal ions, acrylates, quaternary ammonium ions, heterocyclic ammonium ions, and sulfonium salts. 

With large-surface-area membrane filter media, the interpretation of the true bubble point can be further complicated because of the diffusion of the test gas through the media. Because the filter media are more than 70% void space, a liquid-wetted membrane is virtually a thin film of liquid across which a test gas will diffuse, governed by Fick s law. 

The catalyst is often loaded on screens supported by a stainless steel grid near the bottom of the reactor. Often, large inert ceramic balls are loaded at the very bottom, with slightly smaller ceramic balls above the first layer, and then the catalyst. Smaller inert ceramic balls can also be loaded above the catalyst bed and topped off with the larger balls. The layer of inert balls can be 6 in to 2 ft in depth. The balls restrict the movement of the bed and distribute the liquid across the catalyst. 

In concept, this definition describes the flux of liquid across the tray. An alternative definition sometimes used for describing liquid load is the flow parameter, Fw... 

Adhesion between two liquids. The attraction exerted by one liquid across the interface on the other requires that work must be done to separate them. It may easily be shown that this work, called the adhesional work9 between the liquids, is equal to the sum of the surface tensions of the liquids singly, less the interfacial tension of the liquid-liquid interface. Suppose A and B (Fig. 1) are the liquids in a column one square centimetre in cross-section then when they are in contact the energy of the interface is yAB when they have been separated by a direct... 

As stated by Holmes and Chen [12], the reasons for using gas-liquid or vapor-liquid separators are to recover valuable products, improve product purity, reduce emissions, and protect downstream equipment. Gas-liquid separators are used after flashing a hot liquid across a valve. In this case the separator is called a flash drum. 

Centrifugation was also used for automation of one incarnation of SPOT synthesis. In this case the synthesis is performed on a functionalized polypropylene disk of the size of a conventional compact disk. The surface properties of this material allow for the discrete delivery and therefore synthesis at 2500 locations. After coupling, deprotection and washing are realized by delivering appropriate solvents close to the disk center and rapid rotation efficiently sweeps the liquid across the disk surface (108). 

In spite of its name, it uses hydrodynamic drag to exert a removal force on the siuface particles. Brush bristles do not contact the particle or the surface but rather act as oars or paddles that push liquid across the wafer surface, dislodging particles. This technique is effective for particles larger than 1 pm. It is suitable for both hydrophilic and hydrophobic wafers. 

Conversion to Murphree Tray Efficiency. For complete liquid mixing on the tray, as found in small columns (e.g., Oldershaws) and in some vacuum columns where the volumetric flow of vapor is much higher than that of the liquid, Eog = Emv- For the opposite case of plug flow of liquid across the tray. 

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