Pumping Aids

They are used to piunp marginally pumpable concrete. Materials that are used for this purpose are water-soluble S5mthetic and natural organic compounds such a cellulose ether, polyethylene oxide, alginates, organic water-soluble flocculants, emulsion of organic materials, fine clays, kaolin, diatomaceous earth, and calcined pozzolans. 

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Construction. The addition of PEO to concrete has been a subject of several iavestigations (172). Research studies and patent Hterature suggests that PEO can be used as a pumping aid to concrete where the lubricity of PEO allows concrete to be pumped to longer distances (173—176). In addition, PEO is also used to disperse the water more uniformly ia the concrete mixture that promotes better uniformity of the concrete mixture. Eormulations ia the constmction industry are proprietary and not easily available. 

Miscellaneous admixtures Those other than what have already been described and are known to impart many benefits to concrete. Examples are latexes, corrosion inhibiting admixtures, alkali-aggregate expansion reducing admixtures, pigments, pumping aids, shotcreting admixtures, etc. 

This type of filtration is almost invariably performed with the aid of a Buchner flask and funnel, by means of which a rapid and almost complete separation can be obtained. The Buchner flask A (Fig. 4) consists of a simple thick-walled conical flask with a short side-arm for connection to a water-pump. Into the neck of the flask is fitted the Buchner funnel B which consists usually of a cylindrical porcelain funnel, the bed of which is pierced by a... 

Toluene-/ sulplionamide is almost insolubb in cold water, but dissolves readily in sodium hydroxide solution (as the sodium derivative) aid is immediately reprecipitated on the addition of strong acids. To show the formation of the sodium derivative, dissolve about o-2 g. of metallic sodium in about 10 ml, of ethanol, cool the solution, and then add it to a solution of 1 g. of the sulphonamide in 20 ml. of cold edianol. On shaking the mixture, fine white crystals of the sodium derivative, CH,C,HjSO,NHNa, rapidly separate, and may be obtained pure by filtering at the pump, and washing firet with a few ml. of ethanol, and then with ether. 

The action of the manostat may be explained with the aid of Fig. II, 23, 6. Mercury is introduced into the container until the disc of the float just makes contact with the oriflce, when the pressure is equalised inside and outside the float. The device is connected to the pump and to the system by way of a large reservoir and a manometer. With the stopcock open, the pressure in the system is reduced by way of a by-pass between the pump and the system until the desired value as read on the manometer is reached, then both the stopcock and by-pass are... 

This pressure is readily attained by placing an air leak between the water pump and the apparatus or, better, with the aid of a manostat. Figs. II, 23, 4-7. 

METHYL y-BROMOCROTONATE JV-Bromosuccinimide. Dissolve, with the aid of rapid mechanical stirring, 80 g. of pure succinimide (Section V,14) in a mixture of 150 g. of finely crushed ice and a solution of 32 g. of sodium hydroxide in 200 ml. of water contained in a litre beaker and cooled externally by ice. Immediately the imide has dissolved, continue the vigorous stirring and introduce 42 -5 ml. of bromine in one lot from a separatory funnel supported over the beaker it is essential that the bromine be instantly suspended in the solution. After stirring vigorously for 2 minutes, filter at the pump and... 

Most process plant engineers utilize some form of preprinted pump calculation worksheet or a computer to aid in the coUection of information. 

T. Dahl and L. Nelik, Computer Aided Design of a Centrifugal Pump Impeller, ASME 85-WA/EE-lO, Washington, D.C., 1985. 

Techniques for handling sodium in commercial-scale appHcations have improved (5,23,98,101,102). Contamination by sodium oxide is kept at a minimum by completely welded constmction and inert gas-pressured transfers. Residual oxide is removed by cold traps or micrometallic filters. Special mechanical pumps or leak-free electromagnetic pumps and meters work well with clean Hquid sodium. Corrosion of stainless or carbon steel equipment is minimi2ed by keeping the oxide content low. The 8-h TWA PEL and ceiling TLV for sodium or sodium oxide or hydroxide smoke exposure is 2 mg/m. There is no defined AID for pure sodium, as even the smallest quantity ingested could potentially cause fatal injury. 

Feed Slurry Temperature Temperature can be both an aid and a limitation. As temperature of the feed slurry is increased, the viscosity of the hquid phase is decreased, causing an increase in filtration rate and a decrease in cake moisture content. The limit to the benefits of increased temperature occurs when the vapor pressure of the hquid phase starts to materially reduce the allowable vacuum. If the hquid phase is permitted to flash within the filter internals, various undesired resiilts may ensue disruption in cake formation adjacent to the medium, scale deposit on the filter internals, a sharp rise in pressure drop within the filter drainage passages due to increased vapor flow, or decreased vacuum pump capacity. In most cases, the vacuum system should be designed so that the liquid phase does not boil. 

Turbulence and high fluid velocities resulting from normal pump operation accelerated metal loss by abrading the soft, graphitically corroded surface (erosion-corrosion). The relatively rapid failure of this impeller is due to the erosive effects of the high-velocity, turbulent water coupled with the aggressiveness of the water. Erosion was aided in this case by solids suspended in the water. 

In a 3-I. round-bottomed flask 250 g. of commercial calcium hypochlorite is dissolved in i 1. of warm water and a warm solution of 175 g. of potassium carbonate and 50 g. of potassium hydroxide in 500 cc. of water is added. The flask is stoppered and shaken vigorously until the semi-solid gel which first forms become quite fluid. The suspended solid is removed by filtration on a large Buchner funnel, washed with 200 cc. of water, and sucked as dry as possible with the aid of a rubber dam and an efficient suction pump. The filtrate of approximately 1500 cc. is placed in a 3-I. round-bottomed flask and is ready for the addition of methyl /3-naphthyl ketone. 

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