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  • Polymer and Materials Science  (13)
  • Dosieren  (1)
  • 1
    ISSN: 0009-286X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Flow control for small metering pumps with continuous and pulsating flow. Metering of small flows with high discharge pressure is performed mainly by displacement metering pumps. The necessary mass-flow control shows problems with pulsating piston- or diaphragm metering pumps. A survey explains the presently available continuous and discountinuous methods of mass- and volume flow control. Special investigations have been performed with differential scales and mass flow meters based on the Coriolis- and the thermal principle. The differential weighing method shows good accuracy down to minimum mass flows of 0.1 kg/h. This method is expensive and requires vibration protected installation. The Coriolis flow meter, applicable over a similar range, precisely integrates the pulsating signal, but requires damping or signal averaging for regulation purposes. Thermal flow meters prove rather sensitive to temperature fluctuations. Under stable conditions and with proper calibration this principle may be applied to flows even below 0.1 kg/h.
    Zusätzliches Material: 26 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    ISSN: 0009-286X
    Schlagwort(e): Dosieren ; Schüttguttechnik ; Schneckendosierer ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 57 (1985), S. 395-409 
    ISSN: 0009-286X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Dosage of solids and liquids. Dosage of reaction components is an important step in chemical engineering processes. In an age of increasing automation, the development of dosage procedures is highly topical; electronics and data processing have long made inroads into dosage procedures. However, today's more stringent demands with regard to pressure, temperature, viscosity, and abrasion necessitate intensified research and development efforts. The present article considers mainly volumetric and geometric dosage methods. The many types of metering pumps cover a large area of dosage of liquids. Minimal flow rates, pressures up to several 1000 bar, and also dangerous and difficult fluids can all be safely handled. Leakproof designs with membranes, tubes, or bellows as displacement devices are particularly important nowadays. Volumetric dosage of solids requires establishment of a reproducible packing density. The survey considers the principle methods of dosage (also against pressure) with special emphasis on screw dosage. Gravimetric dosage methods are extremely reliable and accurate but generally require volumetric systems for energy supply. Especially when used in combination with metering pumps or screw dosage, differential balances have numerous possible applications.
    Zusätzliches Material: 25 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    ISSN: 0009-286X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Wear of automatic pump valves by abrasive suspensions. In pumping of abrasive suspensions with reciprocating displacement pumps against high pressures, the pump valves prove to be subject to serious wear. Wear of the piston seal can usually be avoided by washing or by separating membranes. Pump valves are fitted with elastic or rigid seals. To resist corrosion and temperature effects, frequently the only possible approach is to finish them in metallic or carbide materials. The major kinds of wear are demonstrated by a tribological study. The rates of wear found for a real valve model with a high pressure experimental setup depend upon the pressure and frequency of reciprocation. A hardness-dependent region of instability exists where wear scoring arises. The volume wear rate for various arrangements of materials and abrasive particles exhibits a crest/trough nature. A design strategy and construction aspects are considered and compared with practical experience.
    Zusätzliches Material: 22 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 61 (1989), S. 136-140 
    ISSN: 0009-286X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Accuracy of dosage. Confusion sometimes surrounds the concept of dosage accuracy. For this reason, standard definitions and testing and calculation procedures are proposed for dosage accuracy, dosage error, and dosage constancy. Representation of the relationship between dosage error and dosage constancy within the area of tolerance of the dosage accuracy is new. Since the measurement of all error quantities is always bound to relate terms such as short-term, long-term, and momentary dosage error to a stated time base. This also facilitates a conceptually smooth transition to operating dosage errors observed in long-term operation. It would be convenient if some standardization of the concepts, and possibly a set of rules, could be developed on this basis. Evaluation of measured results on comparing guarantees would then be conducted in relation to the accuracy of measurement.
    Zusätzliches Material: 13 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 6
    ISSN: 0009-286X
    Schlagwort(e): Oszillierende Verdrängerpumpen ; Druckschwingungen ; Pulsationsdämpfung ; Blenden ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 7
    ISSN: 0009-286X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Developments in dosage of bulk solids. Dosage of bulk solids is a fast developing field of process- and production automation. Developments are determined directly by the current demands of the production process, with the properties of the bulk solids and the process itself playing an important role. A survey of proven dosage techniques from the viewpoint of the operating principles, properties, applications, and limitations demonstrates the great variety of problem solutions. An important difference between the individual dosage techniques is the nature and accuracy of mass limitation. The most accurate techniques are the gravimetric dosage methods, with discontinuous weighing giving the greatest accuracy. Developments have been greatly influenced by the state of weighing cell techniques, weighing electronics and computer engineering. The development of measured data acquisition and processing of control, and of instrumentation are described, compared, and assessed. A trend towards system responsibility and development on the part of manufacturers is noted. A accurate dosage of bulk solids requires constant flow of the solids and finely adjustable control devices. The principal interferences in bulk solids flow and measures for their avoidance are shown by means of examples. Successful solution of dosage tasks ultimately requires agreement between manufacturers and processors with regard to definition, determination, and control of dosage accuracy during calibration and during long term operation.
    Zusätzliches Material: 20 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 8
    ISSN: 0009-286X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Stirring Devices in Screw Metering Equipment - Action and Design Strategy. The accurarcy of metering by screw dosage equipment with or without gravimetric control depends primarily on the flow of material to the discharging screw. In the case of cohesive solids, stirring devices are generally required to prevent bridging. Experimental observations show that flow conditions correlate directly with the intensity of stirring. Mass flow in the metering container and hence optimum constancy of metering are attainable only from certain stirring efficiencies upwards. Cases of interference to metering due to poor flow of solids can be explained and overcome by modified dimensioning. The effects of the principal parameters - geometry and speed of rotation of the stirrer - are studied with the aid of two stirrer configurations - viz. overhead and concentric. Straightforward model calculations provide a mathematical method of estimation for optimum and reliable stirrer dimensioning also applicable to strongly cohesive solids.
    Zusätzliches Material: 22 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 9
    ISSN: 0009-286X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Pressure Pulsations Caused by Reciprocating Pumps in Piping Systems. The safe design of piping installations for reciprocating pumps requires proper knowledge about the pump/installation interaction. In many cases critical resonance effects can be avoided by proper piping geometry or improved pump performance with respect to the volumetric efficiency (primary measures). Normally it is necessary to use various secondary dampening methods which can influence the acoustics of the piping system. Several examples of experimental computer simulations of damper action - upstream and downstream - are presented for fluidand gas-filled damper versions. The influence of entry geometry of the dampers is explained, hints on the proper geometry of the entries are given and the effects of various dampers and their influence on the total acoustics are discussed. Special reference is made to the effect of orifices as dissipative and acoustic elements in piping systems. The investigation shows the importance of analyzing of the total system of pump, piping installation and vessels or reactors and the application of computer simulation for piping design.
    Zusätzliches Material: 28 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 10
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 58 (1986), S. 183-195 
    ISSN: 0009-286X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Pumps and compressors for high pressures - strength, seals, wear. In high pressure processes pumps and compressors are used for the pressure range of 100 to 4 000 bar. Very careful design is necessary because of the extreme mechanical demands. The special features of high pressure technology are explained. The methods used for generating high pressures - displacement or fluid flow machine - impose design limitations, partly by the final temperature, Mach number, material fatigue, or vibrations. A survey of typical high pressure pumps and compressors shows the range and limitations of application. There is a definite trend to leak-free systems. The best design of thick-walled components with pulsating pressureload avoids grooves, requires smooth surfaces, and uses tough, clean, and high-strength steels. The various designs of dynamic seals are explained and the state of the art is depicted. Detailed reference is also made to the exceptionally difficult wear problem of oscillating pump valves with abrasive suspensions.
    Zusätzliches Material: 26 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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