Showing papers on "Volumetric flow rate published in 1968"

An electromagnetic catheter flow meter for determination of blood flow in major arteries.

Abstract: In a previous communicationl an electromagnetic catheter flow meter was described which permits determination of blood flow supplied through branches of the aorta to internal organs. That approach left the important problem of measuring axial blood flow through the aorta and other major blood vessels unsolved. The present paper describes a modification of the above device which may prove applicable to the pulmonary artery and vena cava. Whereas the original intravascular flow meter1 measured the rate of volume flow in the fashion of normal performance of an electromagnetic flow meter, the same sensor in its present adaptation performs the function of a velometer, i.e., of a transducer which measures the local linear velocity of the fluid. This does not preclude, however, its use for the determination of the rate of volume flow through the cross section of the aorta, as will be pointed out below. Electromagnetic velometry, i.e., the determination of fluid velocity distribution in space and time by a sensor responding directly to the local flow velocity, was initiated in 1943.2 3 Two approaches were used. (a) An external magnetic field was generated across a channel through which a pair of fine, shielded electrodes were moved to sense the local fluid velocity. (b) A "self-contained unit" was constructed which was based on an inversion of the normal configuration of the electromagnetic flow meter (EMFM\). In the standard EMFM the fluid whose velocity is measured passes through a lumen surrounded by the magnet structure and is contacted by the electrodes on the outer rim of the lumen. In the velometer in question,3 the flowing fluid streams around the transducer so that the magnet and electrodes are internal with respect to the fluid masses whose velocity is being measured. For a more detailed description, we quote from the original paper: "a small exploring probe containing a minute a.c. electromagnet next to its pick-up electrodes was built, with the iron core of the magnet consisting of a flat, approximately elliptical disk of 2.5 by 6 mm and about 1 mm in thickness. The iron core and the coil which is wound around its rim were thoroughly insulated by a coat of water-resistant varnish. The tips of the pick-up electrodes were fixed at the extremities of the major axis. For effecting measurements, the self-contained unit is placed in the streaming with the faces of the disk parallel and the major axis perpendicular to the direction of the flow. By changing the orientation of the unit, one may determine the velocity components in any desired direction. Calibration experiments showed the deflections obtained with the self-contained unit to be a linear function of the velocity." The principle of this velometer is, of course, suitable for measurement of blood

Double rate flow controller

Abstract: A double rate flow controller including a means for permitting fluid flow at a first high flow rate, a means for reducing the first flow rate to a second lower flow rate and a means for regulating the volume of water passing through the flow controller during the high flow condition before the high flow rate is terminated and the low flow rate begins.

Testing and Analyzing Low-Permeability Fractured Gas Wells

Abstract: A series of gas wells were tested by flowing each well at a constant rate until semi-radial flow was apparent. Each well was then shut-in for a build-up. After a sufficient build-up was obtained, another flow test was commenced but at a higher flow rate than the first test. It was observed that the fractures in the wells influenced the pressure behavior for approximately 18-48 hr, depending on the flow rate, before semi-radial was predominant. When a low permeability gas well has induced fractures that are vertically oriented, the early flow geometry is essentially linear. How to determine when a flow test has been conducted long enough so that the most representative values of effective permeability, wellbore radius, and turbulence factor can be calculated is shown. From the linear pressure data, valuable information about the fracture treatment such as the effective flow area and vertical fracture efficiency can be determined. (12 refs.)

Flow-rate dependence of gel permeation chromatography

Abstract: Analysis of polystyrene standards by gel permeation chromatography over a wide range of flow rates revealed two sources of error in volume measurement. These errors arise from solvent evaporation in the siphon chamber and from solvent continuing to flow into the siphon during discharge. Appropriate corrections are discussed, and a vapor feedback loop to eliminate the solvent evaporation error is described. The flow rate dependence of the GPC calibration curve, expressed in the corrected elution volumes, appears different from that reported in the literature. The corrected flow rate dependence of peak elution volumes is in agreement with the expectation of diffusion and exclusion theories.

Viscous dissipation in capillary flow of rigid PVC and PVC degradation

Abstract: The steady state, non-isothermal behavior of rigid polyvinyl chloride melt, flowing in capillaries of circular cross-section, was investigated by solving, with the aid of a digital computer, the momentum and energy balance equations. It was assumed that the polymer melt can be described by the “Power Law” constitutive equation. The shear rate, temperature and pressure dependent properties of the fluid were obtained experimentally. The effects of the thermal degradation of PVC on its viscosity, were also introduced in the equations of momentum and energy. The velocity, temperature and pressure profiles, obtained for both adiabatic flow and flow through a tube of constant wall temperature, indicate that considerable heating of the melt, due to viscous dissipation, can be achieved at moderate flow rates. Thermal degradation occurs in the capillary under certain conditions of temperature history and residence time of the fluid. The results of this work are in fair agreement with experimental results in this area.

Devices for venting gaseous and/or vaporous media

Abstract: A vent device for venting a gaseous and/or vaporous medium into the atmosphere, in particular for venting such a medium from a generally enclosed liquid container when liquid is entering the container, said vent device providing a vent orifice arranged for flow therethrough of the medium being vented, and comprising means for varying the cross-sectional area of the orifice in response to the volumetric rate of flow of the medium being vented, said cross-sectional area increasing with increasing flow rate of the medium and decreasing with decreasing flow rate of the medium.

Fluid flow system

Abstract: In a fluid flow system having at least two flow branches whose pressure drop variations with flow rate changes are different, a flexible orifice is placed in a branch with the lesser pressure drop. The pressure drop across this orifice, which expands with increasing flow rate, tends to balance the pressure drop in the other branch or branches so as to make possible predetermined control of the fluid flow in the system.

Response of a tubular heterogeneous catalytic reactor to a step increase in flow rate

Abstract: The vapor phase dehydration of ethanol to diethyl ether, as catalyzed by ion exchange resin, has been studied experimentally and theoretically for the transient state period following a step increase in flow rate A mathematical model is developed to account quantitatively for the effects of adsorption and surface reaction on the product distribution in the effluent of a tubular reactor The solution of the model is in good agreement with the experimentally observed behavior

A model for the prediction of velocity and void fraction profiles in two‐phase flow

Abstract: An experimental study of velocity and void-fraction profiles has been carried out for the cocurrent two-phase flow of both air and water, and air and glycerine-water systems. The investigation was restricted to flow in a horizontal, 1 in. diam. tube with primary emphasis on the bubble flow regime. The assumptions which must be made to reduce the general equations of continuity, momentum, and energy to the forms appropriate for two-phase flow are presented and the equations simplified for the case of no local slip. A model is proposed which allows the determination, by trial, of the two-phase velocity and void-fraction profiles. The profiles generated by the use of the model in conjunction with experimental sampling data are presented, the profile shapes are discussed, and their variations with Reynolds and Froude numbers and gas volumetric flow fraction are shown to be self-consistent. The horizontal profiles are found to be in fair agreement with those predicted from Levy's mixing length theory. A correlation scheme is outlined which, supplemented by data over wider ranges of operating conditions, would serve as a method for estimating pressure drops in two-phase flow.

Performance Characteristics of a New Continuous-Flow Electrophoresis Instrument

Abstract: An instrument is described for the continuous separation of particles by means of electrophoresis. The effect of field strength, electrolyte flow rate, and sample flow rate on migration distance and particle band width were investigated. The interrelationships between the various operational parameters and particle band resolution are discussed.

Flow rate and low flow indicator

Abstract: A flow measuring and monitoring system is provided that both measures flow and provides an indication when the flow falls below a predetermined minimum flow rate.

Measurement of flow rate of participate solids in solid-liquid mixtures

Abstract: Although N. Brook has mentioned in his research on flow measurements of particulate solid-liquid mixtures that the flow in vertical pipes should be modified by slip between the particles and the water, the slip effect has not been taken into account. !n this paper, theoretical and experimental methods are presented for measuring the flow rate of particulate solids in solid-liquid mixtures in view of the slip velocity by using vertical connected

On Float-Area-Type Flow Meters : (Non-Newtonian Fluid)

Abstract: The float-area-type flow meter, frequently known as a rotor meter, is an important flow rate measuring device for the flow rate is small. The purpose of this report is to introduce relations about the performance of float-area-type flow meters for non-Newtonian fluids following the "power law" model, and to verify the theoretical performance by experiments. It is shown, as a result, that the procedure for obtaining the flow rate characteristics for this kind of flow meter is theoretically formulated. The theoretical results are compared with those of experiments which are carried out with several-percent solutions of CMC and good agreement is found to exist between them.