Abstract: A method of determining viscosity can include connecting a bypass flow passage in parallel with a main flow passage, connecting a mass flowmeter and a variable flow restrictor in the bypass flow passage, and connecting at least one viscometer to the bypass flow passage. A rheology measurement apparatus can include a bypass flow passage connected in parallel with a main flow passage, a mass flowmeter connected in the bypass flow passage, and a pipe viscometer connected in the bypass flow passage. Another bypass flow passage may be connected in parallel with the main flow passage, with another mass flowmeter connected in the second bypass flow passage.

Abstract: The present disclosure relates to a method for operating a flow measuring point for media having at least one liquid phase, the flow measuring point including: a Coriolis measuring device for measuring the mass flow rate and the density of a medium flowing through a pipeline; and a pressure-difference measuring apparatus for sensing the pressure difference between a flow region arranged upstream of the Coriolis measuring device and a flow region arranged downstream of the Coriolis measuring device, wherein a flow measurement based on measured values of the pressure difference is corrected by means of measured values acquired using the Coriolis measuring device.

Abstract: Provided are apparatuses and methods for rapid viscometry of whole blood, plasma, and/or whole blood during coagulation. The disclosed technology measures the blood viscosity through the full range of flow rates found in the cardio-vascular system. This in vitro test can be performed on fresh or anticoagulated whole blood to predict the flow properties (e.g., viscosity) anywhere in the body from the aorta to the deep veins of the leg. The result is a flow-rate dependent blood viscosity curve (viscosity profile) that helps the clinician predict and manage the patient's vulnerability to thrombosis and embolism, which is of particular relevance to COVID-19 patients and/or ICU patients.

Abstract: A regulator assembly is disclosed. The regulator assembly can include a regulator having a gas inlet and a gas outlet. The regulator assembly can also include an extension pipe having a proximal end and a distal end. The regulator assemble can also include an orifice disposed in the extension pipe for modification of the gas flow.

Abstract: A fluid flow meter is provided that generates a pulsed output to account for viscosity variations. The fluid flow meter includes a controller with a data storage that is configured to store correlations of fluid pressure, volumetric flow rate and pulse frequency for different viscosities, based on a calibration of the fluid flow meter. A pressure sensor is configured to be connected in parallel to a flow chamber of the fluid flow meter for measuring the pressure across the flow chamber.

Abstract: Device that can be used in an enhanced oil recovery method by injection of a solution of water soluble polymer and brine having a viscosity below 1000 cps that includes a mixer, and preferably a static mixer, capable of homogenizing the solution on-line; a device capable of measuring the viscosity of the homogenized solution, continuously, downstream of the solution injection pump, at a pressure below or equal to 250 bars, and preferably between 50 and 250 bars, and at a temperature below or equal to 120° C., and preferably between 40 and 120° C., by measuring a pressure drop in a calibrated tube, at a constant rate of flow.

Abstract: The invention relates to a measuring nozzle for determining the extensional viscosity of polymer melts during their processing, comprising a flow channel which has a rectangular cross-section and which has a transitional section (3) between an inlet section (1) and an outlet section (2) with respective constant cross-section, which transitional section tapers hyperbolically in the flow direction (8) between two mutually opposite channel walls (6 and 7).

Abstract: An universal machine is comprised of the arrangement of a set of modules (CM) that make up means of rheological and mechanical tests for the assessment of longitudinal forces perpendicular to the rotation direction of an alternate current servomotor. Its modules are comprised of: a) structural organization; b) electronic components cabinet of the electronics system (St)/(Sw); c) dry gear reducer; d) alternate current servomotor; e) fast coupling system for changing geometries; f) test containers, as well as devices for the execution of materials in hardened state; g) load cell device for recording regular longitudinal forces. The machine provides the interconnection with a data processing system (PC) and the aforementioned modules (CM) are controlled by a specific electronic system (St) for speed control, torque control and rotation direction.

Abstract: The invention relates to a piezoelectric sensor for the improved measurement of mechanical variables such as force, pressure or measurement variables which are derived there from, particularly a PVDF film sensor having an improved sensitivity and temperature stability of the measurement signal for pressure measurements that vary in time and/or space, and for the one-and two-dimensional determination of the position and propagation velocity of pressure fluctuations and pressure waves with a single measurement sensor at a measurement location. A preferred field of application of the invention is the non-invasive, low strain and continuous measurement of the pulse rate and the systolic and diastolic blood pressure of humans and animals by determining the velocity and the signal form of the pulse waves.

Abstract: A system and method for generating a change in pressure proportional to fluid viscosity is disclosed herein. The system can comprise a first pilot stream, a second pilot stream, and a pressure sensing device that reads a differential pressure across a first junction on the first pilot stream and a second junction on the second pilot stream. The first junction is between a first section having a first predominant pressure loss characteristic, and a second section having a second predominant pressure loss characteristic. Similarly, the second junction can be between a third section having a third predominant pressure loss characteristic and a fourth section having a fourth pressure loss characteristic.

Abstract: The invention relates to a rheometer (100) for high-viscosity materials and to a device and a method for estimating, by means of such a rheometer (100), the feeding pressure to be applied in order to overcome the feeding resistance of high-viscosity material in a pipe. The rheometer (100) has a receptacle for holding high-viscosity material in the receptacle. The receptacle is designed as a standard pipe section (102) that can be filled with high-viscosity material (300). In the rheometer (100), the standard pipe section (102) and high-viscosity material (300) filled into the standard pipe section (102) can be made to linearly move relative to each other at a first rate and at another rate differing from the first rate.

Abstract: In one general aspect, a capillary viscometer is disclosed that includes a source of fluid pressure, a pressure transducer responsive to the source of fluid pressure, and a first capillary tube having an inside volume that is hydraulically responsive to the source of fluid pressure. A two-dimensional array of optical detectors is positioned proximate the first capillary tube with a first plurality of its detectors optically responsive to the inside volume of the first capillary tube and including an image data output. An acquisition driver circuit is responsive to the image data output of the two-dimensional array to acquire a series of successive images of the inside volume of the first capillary tube. Viscosity computation logic is responsive to the acquisition driver circuit and the pressure transducer, and operative to compute the viscosity of the fluid from pressure values received from the pressure transducer and the succession of images of the inside volume of the first capillary tube.

Abstract: A measurement apparatus and method for determining a viscosity of a fluid are disclosed. A predetermined pre-fill portion of a sample of the fluid is injected into a capillary at a predetermined flow rate. The pressure differential across the capillary is determined, and the measurement is aborted when the measured pressure is greater than a predetermined maximum pressure. When the measured pressure is less than the predetermined maximum pressure, the remaining portion of the sample is injected into through the capillary. The viscosity of the sample is calculated based on a pressure within the capillary during the injection of the remaining portion of the sample.

Abstract: A method for measuring the dynamic viscosity and the density as physical quantities of an essentially non-compressible measuring medium may include introducing a non-compressible measuring medium in a vessel charged with a compressible medium, where the non-compressible measuring medium constitutes a fraction volume of a total volume of the vessel. The method further includes measuring an initial pressure of the compressible medium, modifying the total volume of the vessel by a predetermined modification volume, and measuring a modified internal pressure of the compressible medium in the vessel effected by the volume modification. Finally, the method may include causing liquid measuring medium to flow through an opening of the vessel through a capillary tube, where the modification internal pressure is measured at one measuring point and where the initial pressure of the compressible medium surrounding the liquid measuring medium is measured after discharge out of the capillary tube.

Abstract: A method for estimating the viscosity of a liquid in an aspirating or dispensing probe, includes: measuring a reference pressure which is the pressure inside a metering tip when no dispense or aspirate is occurring (Pref); dispensing or aspirating a liquid having a volume of air between the liquid and the pumping mechanism of the probe; stopping the aspirate or dispense; measuring the pressure (Pstop) inside the tip at a time (t) which is the time when the aspirate or dispense is stopped; measuring the pressure (Pstop?) inside the tip at a time (t?) after t; and estimating viscosity as a function of Pref, Pstop, and Pstop?. In a preferred embodiment, the method is carried out on a diagnostic analyzer.

Abstract: A rheometeris disclosed for determining flow characteristics of a fluid. The rheometer comprises a circuit in which the fluid is arranged to flow. The circuit comprises a duct and a plurality of flow elements, each comprising a flow environment arranged in fluid communication with the duct. The flow environment of each element is arranged to convey fluid from an up-stream position to a downstream position of the respective flow element. The rheometer further comprises pressure sensing means arranged to determine fluid pressure at the upstream position and the downstream position of each of the plurality of flow elements. At least two of the plurality of flow elements comprise different flow environments for the fluid such that the rheometer can determine the flow characteristics of the fluid at a particular instant in time.

Abstract: A viscometer for molten plastic has a housing having first and second relatively displaceable parts with generally complementary and substantially planar faces. The first part is formed with a throughgoing melt passage adapted for connection in a flow system of the molten plastic. A hinge interconnects the parts. An outgoing conduit extends from the melt to a pump intake and from a pump output to an opening on the face of the first housing part. A plurality of sensors on one of the parts are connected to respective openings on the face of the one part. A return conduit extends from another opening on the face of the first housing part offset from the opening of the outgoing line. An exchangeable metal foil formed with a slot into which all of the openings open is engaged tightly between the two faces.

Abstract: Controlling a well injection operation, such as a well fracturing operation, includes identifying a flow characteristic of a fracturing fluid, identifying a flow characteristic of a base fluid used for forming the fracturing fluid, determining an amount of friction reduction change of the fracturing fluid, and adjusting the amount of friction reduction of the fracturing fluid to coincide with a selected friction reduction amount. Identifying a flow characteristic may be performed by a rheology measuring device including a measurement tube, a first pressure sensor disposed at a first position on the measurement tube, a second pressure sensor disposed at a second position on the measurement tube, a flow meter disposed at a third position along the measurement tube, a temperature sensor disposed at a fourth location along the measurement tube, and a control unit interconnected to the first and second pressure sensors, the flow meter, and the temperature sensor.

Abstract: Method and apparatus for estimating an apparent viscosity of a non-Newtonian fluid. The results may be used for selecting equipment for pumping systems.

Abstract: Controlling a well injection operation, such as a well fracturing operation, includes identifying a flow characteristic of a fracturing fluid, identifying a flow characteristic of a base fluid used for forming the fracturing fluid, determining an amount of friction reduction change of the fracturing fluid, and adjusting the amount of friction reduction of the fracturing fluid to coincide with a selected friction reduction amount. Identifying a flow characteristic may be performed by a rheology measuring device including a measurement tube, a first pressure sensor disposed at a first position on the measurement tube, a second pressure sensor disposed at a second position on the measurement tube, a flow meter disposed at a third position along the measurement tube, a temperature sensor disposed at a fourth location along the measurement tube, and a control unit interconnected to the first and second pressure sensors, the flow meter, and the temperature sensor.

Abstract: A micro-fluidic device and methods for measuring one or more rheologic properties of a fluid. The micro-fluidic device includes a substrate and at least one cover bonded to a surface of the substrate with a fluid channel formed in at least one of the cover or the substrate. Further, the micro-fluidic device includes a first differential pressure gauge that can have a first differential pressure sensor in fluid communication with both a first pressure site and a second pressure site. Further still, the micro-fluidic device includes the first pressure site and the second pressure site that can be spaced apart by a first section of the fluid channel. Also, the micro-fluidic device includes a data processor communicatively coupled to the first differential pressure sensor, so as to receive data generated by the first differential pressure sensor.

Abstract: A micro-rheometer for measuring flow characteristics such as viscosity, elasticity, and flow rate of a sample liquid combines well defined micro-fabricated flow channels having geometry changes forming a constriction region therein to a monolithically fabricated pressure sensor arrays. The pressure sensor array positions pressure sensors to measure the viscosity of the sample liquid while flowing in a uniform length of the flow passage and to measure the extensional viscosity while flowing through the constriction region of the passage. The invention can improve the measurement accuracy of the flow rate, viscosities, or elasticities over a wide range of shear rate. The accuracy of the viscosity over a broader range of shear rate or flow rate measurement over broader range of flow rates can be accomplished by employing monolithically integrated pressure sensors fabricated with different sensitivities disposed in a known manner.

Abstract: A method for determining the viscosity and relative change of viscosity of a fluid over plural shear rates caused by a decreasing or increasing pressure differential resulting from fluid flow to a defined chamber in a capillary system. The flow of liquid through the capillary restriction, the pressure variation rate and known dimensions of the system can be used typically by a processor to determine a rheological property of a fluid.

Abstract: Methods and apparatus are disclosed for characterizing flow of magneto-rheological suspensions through microchannels. The apparatus includes a pump for pumping a the magneto-rheological suspension; a microchannel hydraulically coupled to the pump and configured to receive the magneto-rheological suspension from the pump; a manifold hydraulically coupled between an outlet of the microchannel and the pump; a static pressure tap configured to convey a static pressure of the manifold; a pressure sensor hydraulically coupled to the pressure tap and configured to receive the static pressure conveyed therefrom; and a magnet positioned to direct a magnetic field toward the microchannel and contents disposed therein.

Abstract: A fluidic analysis device includes a small plate (2), at least one flow channel (4) formed in this plate, means (18) for directing a fluid into the flow channel, and at least two analytical means (28?, 28?, 361, 362 46) suitable for analyzing a sample of unique composition of said fluid.

Abstract: Method and apparatus are disclosed for estimating an apparent viscosity of a non-Newtonian fluid. The results may be used for selecting equipment for pumping systems.

Abstract: A method for differentiating between a liquid sample having clogs therein and a liquid sample having an abnormally elevated viscosity during a liquid aspiration process by relating the ratio between the maximum negative pressure during aspiration and an equilibrium pressure prior to dispensation to viscosity.

Abstract: A gas viscosity sensor comprises a signal processing circuit and a sensor element, including a gas pressure generating system and a differential pressure measuring system in fluid communication therewith, the differential pressure measuring system comprising a measuring chamber (14) bounded by a thin membrane (28), an inlet-outlet channel or orifice interconnecting the measuring chamber to a source of gas for which the viscosity is to be determined, the inlet-outlet channel or orifice having dimensions adapted to provide resistance to the outflow and inflow of gas in the measuring chamber, and a membrane displacement sensor (32) adapted to measure a time dependent displacement of the membrane due to pressure variations in the measuring cavity.

Abstract: A system for determining a viscosity of a fluid is provided. The system includes an intake chamber, a tube, a piston, an actuator, a sensor, and a processor. The tube communicates with the intake chamber and includes a channel including a cylindrical portion with a constant diameter cross section. The piston is mounted in the intake chamber. The actuator is configured to move the piston within the intake chamber at a constant speed during a time window to regulate a fluid in the cylindrical portion. The sensor is configured to measure a pressure a plurality of times during the time window to define a plurality of pressure measurements. The processor is configured to receive the defined plurality of pressure measurements, to determine a slope associated with the received plurality of pressure measurements, and to determine a viscosity of the fluid based on the determined slope.

Abstract: A method and device for assessing rheological properties of a fluid, including lubricity and viscosity. The invention utilizes a tube into which the fluid is introduced, and relies on tracking the movement of the fluid through the tube either alone or with one or more particles intentionally introduced into the fluid to assess the rheological properties of the fluid. The method and device generally entail flowing the fluid and the optional suspended particle through a passage within the tube, and assessing a rheological property of the fluid within the tube by tracking the movement of the fluid and/or particle through the portion relative to the flow of the fluid through the portion.

Abstract: A micro-rheometer for measuring flow characteristics such as viscosity, elasticity, and flow rate of a sample liquid combines well defined micro-fabricated flow channels having geometry changes forming a constriction region therein to a monolithically fabricated pressure sensor arrays. The pressure sensor array positions pressure sensors to measure the viscosity of the sample liquid while flowing in a uniform length of the flow passage and to measure the extensional viscosity while flowing through the constriction region of the passage. The invention can improve the measurement accuracy of the flow rate, viscosities, or elasticities over a wide range of shear rate. The accuracy of the viscosity over a broader range of shear rate or flow rate measurement over broader range of flow rates can be accomplished by employing monolithically integrated pressure sensors fabricated with different sensitivities disposed in a known manner.

Abstract: An apparatus and method for determining the viscosity and relative change of viscosity of a fluid over plural shear rates caused by a decreasing or increasing pressure differential resulting from fluid flow to a defined chamber in a capillary system. The flow of liquid through the capillary restriction, the pressure variation rate and known dimensions of the system can be used typically by a processor to determine a rheological property of a fluid.

Abstract: A method for determining the viscosity and relative change of viscosity of a fluid over plural shear rates caused by a decreasing or increasing pressure differential resulting from fluid flow to a defined chamber in a capillary system. The flow of liquid through the capillary restriction, the pressure variation rate and known dimensions of the system can be used typically by a processor to determine a rheological property of a fluid.

Abstract: An improved micro slit viscometer includes a combined micrometer depth rectangular slit flow channel with monolithically integrated multiple pressure sensors in the flow channels and a pumping system that injects a test sample to the channel at a desired flow rate. Pressure sensing diaphragm of the monolithically integrated pressure sensors is smooth to minimize the flow disturbance thereby measuring accurate local pressures. With the measurement of the pressures at various locations of the channel the true viscosity of test sample can be calculated. The viscometer may consist of multiple flow channels and thus the true viscosity at multiple shear rates can be measured simultaneously for a given flow rate thereby obtaining a full viscosity curve as a function of shear rate of non-Newtonian liquids in a much faster manner. The viscometer needs only a miniscule amount of sample, which minimizes a waste of test material.

Abstract: An apparatus and methods for analysis of a petroleum product, specifically determining the viscosity of a sample, are disclose. The apparatus includes a sample reservoir for receiving a liquid sample and a pressure regulator for applying hyperbaric pressure to a sample within the reservoir. When pressure is applied to the sample reservoir, the sample is forced through a passageway and a pressure sensor monitors the pressure in the sample reservoir. A drop in the pressure can be used to determine when the reservoir is empty and sample viscosity can be calculated based on the time required to empty the reservoir.

Abstract: A thermally controlled stage is connected within one arm of a bridge of a capillary bridge viscometer so that the bridge can be balanced in situ to provide accurate measurement signals. The thermally controlled stage includes a tuning capillary tubing portion that is wrapped around a thermally conductive core. A resistance heater or a Peltier thermoelectric device is located in close proximity to the capillary tubing portion. The heater or Peltier device and the capillary tubing portion are located within a thermally insulated housing. The heater or Peltier device varies the temperature of the capillary tubing portion to cause a corresponding change in the flow impedance of the tuning capillary tubing portion of the arm of the bridge in which the thermally controlled stage is connected. The temperature of the tuning capillary tubing portion is monitored and adjusted until any pressure differential across the bridge is eliminated, whereby to trim in the balance of the bridge.

Abstract: A microfabricated, a nanoliter capillary viscometer includes a first channel that is defined by a first channel-defining surface in a first substrate and a second channel defining surface in a second substrate. The progress of liquid through this first channel is monitored and used to determine viscosity. Viscosities in the range of 1 cP to 1000 cP are easily measured. Self-calibrating versions of the viscometer are also disclosed.

Abstract: A flow measuring valve device (1) for fluid, the flow measuring valve (1) comprising a first restriction (48) and a second restriction (76) connected in series with the first restriction (48), the flow rates of said restrictions (48, 76) being unequally dependent on the viscosity of the fluid, and a method for determining the viscosity of the fluid by means of the device.

Abstract: Microfluidic devices, systems, and methods measure viscosity, flow times, and/or other flow characteristics within the channels, and the measured flow characteristics can be used to generate a desired flow. Multi-reservoir pressure modulator and pressure controller systems, electrokinetic systems and/or other fluid transport mechanisms can generate the flow, controllably mix fluids, and the like.

Abstract: A viscosimeter for measuring the viscosity of a solution in a solvent includes flow resistances having the smallest possible thickness and a small volume compared with all other parallel and following capillaries in a flow conduit system with two legs. The flow conduit system has three parallel flow circuits among which at least two flow circuits are connected by a differential pressure sensor or sensor for differential pressure. The arrangement includes an inlet which divides into two legs, wherein one of the two legs includes a pressure reducing element, a following branch going to a differential pressure sensor and a pressure reducing element in the feeding conduit to a junction which runs into an outlet conduit. The other leg starting from the branch point includes a pressure reducing element which is connected to the differential pressure sensor and to a resistance capillary in the conduit.

Abstract: A method and apparatus for studying the properties of a fluid are provided in which in which a rheometer is used to obtain, for example, value(s) indicative of the shear stress in the fluid to thereby obtain a set of data. The data is then directly compared using, for example, multivariate analysis, with previously obtained data corresponding to a fluid(s) with known rheological properties. The results of this comparison can then be used, for example, to control a manufacturing process.

Abstract: A viscosimeter for measuring the relative, intrinsic or inherent viscosity of a solution in a solvent with at least one flow resistance and one feeding point for the solution to be examined in a conduit system as well as with respective manometers on the flow resistance which are coupled with a differential amplifier, wherein the viscosimeter includes flow resistances such as disk-shaped or leaf-shaped Venturi nozzles or different KV flow resistances with the smallest possible thickness and with a small volume with respect to all other parallel and following capillaries in a flow conduit system with two legs which contains in the first leg at least three pressure reducing elements, for example capillaries, whereby behind the capillary following the branch point a pressure manometer is provided for with a connected bigger vessel, whereby behind further capillaries connected with each other with different diameters and with a big volume which corresponds to 100 to 1000 times the KV flow resistance in the second

Abstract: The current invention provides a process and apparatus for determining the density of a flowing fluid without requiring knowledge of the fluid's Theological properties. The process of the current invention is capable of providing continuous “real time” analysis of fluid density. The apparatus of the current invention comprises at least two pressure assessment zones fitted with fluid pressure sensing points. Pressure sensing devices connected to the pressure sensing points provide the data necessary to enable the calculation of fluid density.

Abstract: There is disclosed a method of rheometry and to a corresponding rheometer apparatus having particular application to the manufacturing of polymers. The invention provides a method of studying the properties of a polymer. A rheometer having a pump (2) and a die(3) is arranged such that polymer is pumped through the die. Transducers (4) measure pressures within the rheometer. The polymer is supplied to the rheometer with the pump (2) at one speed and value(s) indicative of the shear stress in the fluid within the die are obtained from the transducers (4). This provides a set of data. The data is then directly compared, using multivariate analysis with previously obtained data corresponding to polymer(s) with known rheological properties. The results of this comparison may then be used to control the manufacturing process.

Abstract: Apparatus for measuring the viscosity of a Newtonian fluid, includes a tubular housing which defines an internal cavity; a fluid restriction structure disposed in a first portion of the cavity; and a pressure measuring device disposed to measure the differential pressure in the cavity of the fluid which has flowed through the fluid restriction structure. The apparatus further includes a device for applying pressure to the fluid upstream from the fluid restriction structure to cause the fluid to flow through the fluid restriction structure so that the pressure measuring device measures the pressure differential which is inversely proportional to the fluid viscosity squared.

Abstract: The invention concerns a method whereby a fluid sample is brought (1) at constant pressure Pe and temperature maintaining the heavy fractions, in particular asphaltenes, in dissolved state and/or in stable colloidal state, at the intake (4) of a capillary passage with high pressure drop. Said sample is forced to flow through the capillary conduit, at an increasing flow rate. The method consists in measuring (11) the fluid pressure Ps and the fluid flow rate D (12) at the outlet (5) of the capillary conduit and in representing the variation curve of the quantity &Dgr;P=Pe−Ps or the quantity D as a function of the other quantity or as a function of time. The deposit pressure, characteristic of the threshold of deposit of heavy fractions, is defined as the value of pressure Ps, which corresponds to a change of the slope in the variation curve of the quantity &Dgr;P or the quantity D.

Abstract: A reciprocating pump and a capillary viscometer utilizing the same. Preferably, the inventive reciprocating pump is a syringe pump comprising: a cylinder, an actuated piston, and a floating piston. A chamber is created between the actuated piston and floating piston which may be filled with a pressurant to establish the quiescent pressure of the test fluid. The capillary viscometer comprises: a capillary tube wound about a heated mandrel, a differential pressure transducer, and a reciprocating pump. Test fluid is first pumped at a known rate from a first chamber, through the capillary tube, and into a second chamber. The pump is then reversed and the test fluid is then pumped from the second chamber, back through the capillary tube, and back into the first chamber. The process may be repeated in a continuous, reciprocating manner.

Abstract: In an apparatus for measuring the viscosity of plastic materials including a heatable housing structure, enclosing a controllable material pump for generating a certain material flow, a plurality of capillaries, a melt distributor is provided in the supply line of the material from the material pump to the capillaries with which the material can be directed to either of the plurality of capillaries and each capillary is provided with a pressure and a material temperature sensor providing the values needed for determining the viscosity of the material.

Abstract: Apparatus for measuring the viscosity of a Newtonian fluid, includes a tubular housing which defines an internal cavity; a fluid restriction structure disposed in a first portion of the cavity; and a pressure measuring device disposed to measure the differential pressure in the cavity of the fluid which has flowed through the fluid restriction structure. The apparatus further includes a device for applying pressure to the fluid upstream from the fluid restriction structure to cause the fluid to flow through the fluid restriction structure so that the pressure measuring device measures the pressure differential which is inversely proportional to the fluid viscosity squared.

Abstract: The invention pertains to a process for preparing thermoplastic fibres by melt-spinning an alternating co-polymer composed of alkenes and carbon monoxide in which the polymer is heated to a temperature of at least TNF+5° C.