Abstract: A radiographic method and apparatus for nondestructively monitoring a specimen for density variations are disclosed.A positron-annihilation-radiation-emitting point source is situated approximately midway along the axis separating two detectors sensitive to positron-annihilation (0.511-MeV photon) radiation. The outputs of the two detectors are fed to an electronic circuit that reckons only time-coincident events that are sensed simultaneously in the two detectors. The specimen to be measured is positioned between the source and one of the detectors such that the cone of detected, i.e., coincident, photons intercepts the region of interest. The number of coincidences that are counted in a preset time interval are recorded, or, alternatively, the coincidence count rate is monitored directly with a ratemeter.

Abstract: Apparatus using radiation techniques for measuring coating thickness on continuously moving strip material as it travels along a predetermined path and without altering that path. A shuttle carrying a measuring probe having a radioactive isotope source and a detection device is provided in the path of the strip for reciprocation along a preselected segment of the path. The shuttle and the probe are releasably engaged with the strip and carried thereby for synchronous movement therewith in the direction of travel of the strip during a measurement cycle, and are disengaged from the strip when no measurement is being made, the movement of the shuttle then being controlled by an independent drive mechanism. The shuttle includes a strip guide plate which is tiltable about an axis substantially parallel to the longitudinal axis of the strip in order to orient the surface having the coating so it can be properly presented to the measuring probe.

Abstract: A beta backscatter type of measuring instrument including a workpiece positioning system to permit precise prepositioning of the workpiece surface to be subjected to radiation preparatory to moving the radiation source into operative proximity therewith.

Abstract: A device especially adapted for measuring the thickness of coatings on small, complexly-shaped parts, such as, for example, electronic connectors, electronic contacts, or the like. The device includes a source of beta radiation and a radiation detector whereby backscatter of the radiation from the coated part can be detected and the thickness of the coating ascertained. The radiation source and detector are positioned in overlying relationship to the coated part and a microscope is provided to accurately position the device with respect to the part. Means are provided to control the rate of descent of the radiation source and radiation detector from its suspended position to its operating position and the resulting impact it makes with the coated part to thereby promote uniformity of readings from operator to operator, and also to avoid excessive impact with the part, thereby improving accuracy of measurement and eliminating damage to the parts.

Abstract: Device for bringing about the coincidence between the axis of a measuring probe and a normal to the surface of a part to be controlled and application to the measurement of thicknesses of thin layers.Thus, device (5) forms part of probe (4) on a measuring apparatus comprising means for positioning part (3) and which is constituted by at least one probe translating member (25) making it possible to vary its distance from the part, sensing means (53) integral with the probe for controlling the achievement of coincidence, means (43) for rotating about the axis Y'Y making it possible to give probe axis (A) a direction close to that of normal (N) and means for oscillating probe axis (A) about the said direction in order to achieve the coincidence.

Abstract: An aperture piece to be used in conjunction with backscatter instruments for measuring the thickness of a coating on a substrate of a concave workpiece. The aperture piece being selectively shaped so that a sample support surface, including an aperture through which radiation from a radioisotope is transmitted, may be inserted into the interior space defined by the concave workpiece to engage the concave surface. A method of calibrating backscatter instruments using the aperture piece to make correction for the failure to have a planar mating relation between the sample support surface and the concave workpiece.

Abstract: A coating thickness measuring apparatus for step and repeat coating systems, including; a support member; a common support assembly mounted for pivotal movement about and along a vertical axis; a measuring probe carried by the common support assembly and movable with respect thereto along a horizontal axis; a calibrating disc carried by the common support assembly for rotation with respect thereto about a horizontal axis, having an opening for reception therethrough of the probe and having a plurality of angularly spaced calibration standards movable into selective alignment with the probe; actuators for moving the probe along its horizontal axis, for vertically moving the common support assembly and for rotating the calibration disc; stroke limiting means to halt probe movement between its extreme positions; an indexing bar having a plurality of variably spaced openings; an indexing pin for securing the support member into one of the indexing bar openings; and sensing switches developing signals indicative o

Abstract: A fluorimetric detector for use in detecting or determining a species contained in the flowing liquid eluant of a chromatographic separation, comprising: a .sup.147 Pm or .sup.63 Ni source of beta-particles; a light-sensitive detection means, spaced from the source, for detecting visible fluorescent radiation generated in the eluant by the action thereon of beta-particles and for measuring a count rate of said fluorescent radiation; and flow-causing means to cause the eluant to flow between the source and the detection means is disclosed. Also disclosed, is a method of detecting or determining a species contained in the flowing liquid eluant of a chromatographic separation, the species being either a fluorescent species or a species which quenches fluorescence.

Abstract: A portable device for measuring coating thickness incorporating a radioactive isotope source and a detector. The device is capable of being readily moved from place to place to measure the thickness of thin film coatings applied to various types of substrates, and incorporates spring means for bringing the isotope source holder into intimate contact with the area to be measured and for holding it in that position. The device also includes a locating system whereby a cross-hair or other image is projected onto the surface of the coating the thickness of which is to be measured, at the point where the source holder would contact the coating surface, permitting extremely accurate locating of the device with respect to the area being measured to thereby facilitate the measuring operation and to permit it to be done in an accurate, speedy, and efficient manner.

Abstract: Apparatus for measuring the density of a cigarette rod which is moved lengthwise has a source of penetrative radiation at one side and a single ionization chamber at the other side of the path of the rod. A reciprocable slide or diaphragm causes the radiation to alternately penetrate through the rod and thereupon into the chamber in a first position and to bypass the rod in a second position of the slide or diaphragm. The ionization chamber converts radiation which has penetrated through the rod into first electric signals and the radiation which has bypassed the rod into second electric signals. An evaluating circuit stores each second signal during the next-following interval of generation of first signals, and the evaluating circuit compares the first signals with that second signal which is then stored in the evaluating circuit.

Abstract: A tube arrangement has a first partial tube and a second partial tube, and one fine adjustment arrangement for coaxially displacing the partial tubes with respect to one another. The partial tubes, an aperture ring with a small aperture opening, a beta radiator point source and a GM-counter are coaxially arranged. The partial tubes are connected each with one or two of the following: an aperture ring, the beta radiator point source, and the GM-counter. A blocking means blocks the fine adjustment arrangement. One of the partial tubes is connected galvanically conducting with the GM-counter anode and the other partial tubes are connected galvanically conducting with the GM-counter cathode.

Abstract: An in situ non destructive method employing a radiation device to rapidly determine the density of very thin top layers of material independently of the underlying base material comprising of the steps of: measuring the density D.sub.b of the base layer with an radiation measuring device, determining the thickness t of the top layer, measuring the density D.sub.g of the composite with the radiation measuring device, and determining the density of the top layer from the expression: ##EQU1##where k is a constant.

Abstract: A method and apparatus using radiation techniques for measuring coating thicknesses on continuously moving strip material as it travels along a predetermined path and without altering that path. A shuttle carrying a measuring probe having a radioactive isotope source and a detection device is provided in the path of the strip for reciprocation along a preselected segment of the path. The shuttle and the probe are releasably engaged with the strip and carried thereby for synchronous movement therewith in the direction of travel of the strip during a measurement cycle, and are disengaged from the strip when no measurement is being made, the movement of the shuttle then being controlled by an independent drive mechanism.

Abstract: The present invention is directed to an ionization cell for detecting the presence of very minute concentrations of certain chemical agents. The effective sensitivity of conventional chemical agent detectors is restricted in the presence of certain interferants such as jet fuel, gasoline, smoke, turpentine and the like. Herein a "chemical bias," that is a background concentration of a simulant is provided at the inlet of an ionization detector, which chemical bias is effective by charge exchange to prevent the interferants from dominating the signal.

Abstract: An alpha-ray radiation source photographing device comprising a glove box having an optical window formed in a part of a wall thereof, alpha-ray radiation scintillator, on which an alpha-ray radiation source-containing sample is placed, disposed within the glove box and adjacent to the optical window, and photographing mechanism which includes an optical multiplier tube, a close-up lens system and a camera and is disposed outside the glove box such as to oppose the scintillator. According to this photographing device, the postion of the alpha-ray radiation source can be photographed from the outside of the glove box without inserting a film therein.

Abstract: For hot hydrocarbon liquids and slurries containing a vapor portion derived from a hydrogenation process, the vapor portion is separated from the liquid portion within a separation zone by providing a liquid vortex flow pattern having a gas core. The vapor is withdrawn from the vortex core through an inwardly-extending conduit, and the remaining rotating liquid portion is passed to below the vortex. If catalyst particles are also contained in the hot hydrocarbon liquid, such as in a coal or oil hydrogenation reaction effluent liquid at elevated temperature and pressure conditions, such catalysts can be conveniently separated from a product liquid stream and returned to the reaction zone along with the recycled liquid. A clean liquid stream is withdrawn from the recycled liquid for further processing. If desired, the phase separation zone utilizing a liquid vortex can be provided within the catalytic reaction zone.

Abstract: A component positioning fixture is provided for use with a beta backscatter measuring platen having an apertured seat. The fixture has a plate with an opening therethrough for the apertured seat, and alinement pins properly position the plate on the platen. At least one component positioning member is carried by the fixture plate, the member being selectively adjustable relative to the fixture opening for proper positioning of the component to be measured on the apertured seat of the platen. The positioning member is releasably secured in adjusted position and can include a stop member engageable by the component, a member shaped to receive and position the component and interchangeable with other members shaped to receive and position other components, and a pair of positioning guide members movable relative to each other and to the fixture opening along an axis which can be arranged normal to the axis of movement of the stop member.

Abstract: Process and apparatus for measuring variations in a stream of material, such as thickness in a strip from a mill. A radiation source and detector are positioned at a gauging station. The stream of material moves past the station providing an electrical signal varying as a function of material at the station which signal includes a lower frequency component, a higher frequency cyclical component, and a higher frequency noise component. A circuit for providing a thickness output varying as a function of the lower frequency component of the signal, and a circuit providing an output indicating chatter varying as a function of the higher frequency cyclical component. Digital and analog versions are disclosed.

Abstract: An apparatus for contactless measurement of the thickness of a sheet material comprises a radioactive source located in a protective container which has a collimating hole to output a flow of radiation. There is a radiation detector to sense the radiation passed through the material under control, which is electrically connected to a radiation intensity meter, and also compressed air means for delivery of a jet of compressed air to the measurement point.

Abstract: The apparatus measures the thickness of thin layers on strips and wires which are moved relative to the apparatus. The apparatus is stationary and includes one or more beta emitters directed towards the layer and spatially arranges relative to the longitudinal axis of a beta radiation detector or counting tube which is arranged to the rear of the beta emitter for counting the backscattered beta radiation, and a guide for the strip or wire at a specified distance from the beta emitter. The ratio of the characteristic cross-sectional dimension (D) of the window of the beta radiation detector to the intersecting surface diameter (d) of the intersecting surface layer/intensity distribution curve of the beta emitter, being expressed as D/d=15 . . . 2; with the distance between the layer and the beta radiation emitter being in the plateau region of the curve of the counting rate/distance characteristic obtained by the above feature.

Abstract: A material density radiological measurement system is provided. The system comprises a material density radiological detector, a squaring circuit connected to the output terminal of the detector, a constant multiplying circuit connected to the output terminal of the squaring circuit, and a subtracting circuit connected to the material density radiological detector and the constant multiplying circuit. The system eliminates the nonlinearity of the relationship between the ionization current and the density of tobacco during a measuring operation of tobacco density of a cigarette.

Abstract: The beta ray gauge is augmented with a radiation inspection system for automatically improving products formed into a continuous web such as non-woven paper, non-woven textiles, plastics, etc. For example, the basis weight of a continuous web of paper is measured by passing the web through a beta ray gauge which generates a first signal based on the weight of the paper web. The first signal generated by the beta ray gauge is compared with a predetermined preset reference signal representing the basis weight desired. After the beta ray gauge measures the basis weight in the paper making process, a light inspection system applies a light source across the paper web and detects the light emanating therefrom to provide a second signal based on the characteristics of the paper web.

Abstract: A method of determining the concentration of a substance containing a component capable of induced .gamma. radiation upon irradiation in a neutron flux, especially for the determination of the concentration of fats in meat, in which the body is subjected to the neutron flux, especially from a Cf-252 source, and the induced .gamma. radiation is discriminated and analyzed, especially for the .gamma. radiation at 1.26 MeV, 2.23 MeV and/or 5.3 MeV.

Abstract: A height sensor is provided in a vehicle leveling system having an air spring including a pressurized chamber connected between sprung and unsprung vehicle masses. Two radioactive material sources located within the chamber and attached for movement with the unsprung mass emits beta radiation which passes through the wall of the chamber and a pair of beta detectors outside the chamber and mounted on the sprung mass for movement therewith detects the beta radiation to determine the relative spacing of the sprung and unsprung masses.

Abstract: A backscatter measurement device for measuring the thickness of a coating on a strip of substrate material moving from a feed supply to a take up location at a predetermined speed. A measurement wheel is provided on the rim of which are mouted backscatter probes for irradiating and detecting the backscattered radiation from the coated substrate. The coated strip of substrate material is threaded around the outer surface of the rim. The measurement wheel is rotated at a speed such that the tangential speed of a point on the rim equals the speed of the moving strip whereby the probe and an adjacent point on the strip are stationary relative to one another while the point on the strip is adjacent the rim. Thus thickness measurements may be taken without stopping the movement of the coated strip.

Abstract: In a radioactive ray gauge system, a measuring head continuously detects the thickness of coated material on an advancing sheet. The head has a non-contact type sheet surface-to-head distance detector thereon. The distance detector continuously detects the distance so as to maintain the distance constant thereby eliminating error in the thickness measurement caused by sheet thickness variation, sheet-bending, warping or fluttering.

Abstract: Apparatus and method for determining helium to hydrogen ratios in a gaseous sample by measurement of forward scattering products due to alpha particle collisions with helium and hydrogen contained within the gaseous sample. More specifically, an apparatus is disclosed in which a gaseous sample, contained within an enclosure, is bombarded by alpha particles created by a self contained radioactive source. Baffles are positioned in the enclosure so that only scattering products falling within a predetermined forward scattering angular range can impact a detector assembly. In an embodiment scattered particles are detected by two detectors mounted in tandem, the first completely blocking the second detector with respect to incident scattering products. This embodiment is based on the principle that scattering products have a forward scattering angle .theta. greater than 15 degrees due to alpha particle/hydrogen collisions comprise only recoil protons.

Abstract: The device for non-contact gauging of the thickness of various materials, such as paper, textiles, films and others utilizes the principle of non-contact measurement of said parameter by means of a radioactive source and comprises a radiation source of charged radiation and a radiation detector located on one side of the material to be gauged. The invention is characterized by the fact that the radiation source and the radiation detector are interposed between the poles of a magnetic means. According to one of the embodiments of the invention, the magnetic means comprises two pole sections of which one accommodates the radiation source and the other, the radiation detector, and the section accommodating the radiation source has pole shoes adapted to vary the distance therebetween.This device features a higher accuracy of measurements, makes it possible to use a low-active radiation source, simplifies radiation protection and reduces the mass and size of the device sensing unit.

Abstract: A backscatter measurement device for measuring the thickness of a coating on elements forming a web of substrate material moving from a feed supply to a take-up location at a predetermined speed. A measurement wheel is provided, adjacent to the rim of which is mounted a backscatter probe for irradiating and detecting the backscattered radiation from a coated substrate. The web of substrate material is threaded around the outer surface of the rim. The measurement wheel is rotated at a speed such that the tangential speed of a point on the rim equals the speed of the moving web whereby the probe and an adjacent point on the web are stationary relative to one another while the point on the web is adjacent the rim. Thus thickness measurements may be taken without stopping the movement of the coated web. This backscatter measurement device is further provided with indexing apparatus to position automatically the probe directly adjacent an element to be measured on the web.

Abstract: In order to assay the tritium fuel content in laser fusion targets and/or to measure the pressurization of laser fusion targets of the type which use deuterium and tritium (DT) gas mixtures, without destroying the targets, the flux of beta particles which emerges from the target is measured with the aid of a gas flow proportional counter. The count rates are related to the tritium content and the pressurization. The tritium content in terms of the mass of the tritium in the target can be derived from the counting rate.

Abstract: At least one radioactive source emitting at least two types of radiation is used with two detectors to measure properties of a material which are related to radiation attenuation by that material.

Abstract: The fuel flow into the gasifier of a partial oxidation installation using solid fine-grain or dust-like fuel is determined by a radiometric density measurement of the fuel immediately prior to its entry into the gasifier and while the fuel particles are suspended in a gaseous or vaporous medium.

Abstract: Apparatus for the continuous measurement of increases and decreases in moisture condensation at soil and/or plant surfaces, including a dew measuring probe composed of a sample material, a radiation source disposed underneath the probe and emitting beta particles, and a beta particle detector disposed in alignment with the radiation source and on the opposite side of the probe from the source.

Abstract: A method and an instrument are, herein, disclosed for measuring the absorbed dose rate of beta-rays in sites of the human body. The instrument of this invention consists of a filter, a thin scintillator, a photomultiplier tube, a linear amplifier, a discriminator having a plurality of pulse height selection potentiometers for selectively taking in only pulses of pulse heights above specified upper limit of pulse height discrimination, a shaper for shaping the selected pulses, and a dose rate indicator for counting the shaped pulses.The method and the apparatus of this invention are characterized by making the relationship between the counting rate per fluence rate and the maximum energy of beta-ray equal to the relationship between the absorbed dose rate per fluence rate and the maximum energy of beta-ray, and therefore, the absorbed dose rate can be measured independent of the energy of beta-ray.

Abstract: An improved backscatter instrument for the nondestructive measurement of coatings on a substrate. A memory having selectable memory areas, each area having stored intelligence available which is determinative of the shape of a functional plot of coating thickness versus backscatter counts per minute unique for each particular combination of emitting isotope, substrate material, coating material and physical characteristics of the measuring instrument. A memory selector switch connects a selected area of memory to a microprocessor operating under program control whereby the microprocessor reads the intelligence stored at the selected area and converts the backscattered count of the coating being measured into indicia of coating thickness.

Abstract: Metal layer thicknesses on articles during formation or degradation, as in electroless or electrolytic deposition or chemical etching, are measured and controlled by a process comprising determining the radiation scattering capacity of a corresponding metallic layer deposited on or removed from a test sample while the test sample is present in a bath solution during formation or degradation of the metal layer. Also provided is a novel immersible sensor for measuring the rate and thickness of metal layers being deposited or degraded.

Abstract: A device for taking air gap backscatter radiation measurements at a pair of predetermined distances from the surface of a material is disclosed. The ratio of the first and second measurements are a function of the density of the material when one of the distances is sufficiently large that the measurement is dependent on the chemical content of the material but is independent of surface irregularities and density and when the second distance is greater than the average surface irregularity but sufficiently proximate to the material so that the measurement is independent of surface irregularities but is dependent on the density and the chemical content of the material. The device includes a housing slidably supported between a pair of end plates, a carrying handle for the device and a source within the housing. When the handle is in a first position, the source is disposed in a storage or "safe" position.

Abstract: The disclosure is directed to a non-contacting gage apparatus and method of the type wherein radiation attenuation is measured to obtain thickness information. A first function is developed and is representative of the thickness of standard pieces versus measurement values. A second function is developed and is representative of the Absorption Index of alloy material (to be measured) versus thickness. Calibration can then be effected using the two functions and the nominal thickness of material to be measured.

Abstract: A backscatter measurement device for measuring the thickness of a coating on a strip of substrate material moving from a feed supply to a take up location at a predetermined speed. A measurement wheel is provided on the rim of which are mounted backscatter probes for irradiating and detecting the backscattered radiation from the coated substrate. The coated strip of substrate material is threaded around the outer surface of the rim. The measurement wheel is rotated at a speed such that the tangential speed of a point on the rim equals the speed of the moving strip whereby the probe and an adjacent point on the strip are stationary relative to one another while the point on the strip is adjacent the rim. Thus thickness measurements may be taken without stopping the movement of the coated strip.

Abstract: An apparatus for measuring the weight per unit length of a cigarette rod has a radioactive source to one side of the rod and a detector to the other side of the rod. The source emits a beam of radiation through the rod to the detector. Guide tubes, having air ducts, are located on both sides of the beam. Pressurized air is introduced into the tubes via the air ducts to maintain the rod centrally within the tubes.

Abstract: A normalized count from a digital computer in a layer-thickness measuring device of the beta ray back-scatter type, is fed to a digital-analog converter and a correction circuit which realizes the function X.sub.n corr = X.sub.n +A a.sub.2 X.sub.n.sup.p (1-x.sub.n).sup.q and then to an indicator having a non-linear scale, in which X.sub.n is the normalized count, A is a dimensionless number between +1 and -1, a.sub.2 is a dimensionless number between +0.1 and -0.1, and p and q are dimensionless positive values around unity but different from one another which are permanently wired into the correction circuit.

Abstract: An improved beta backscatter instrument for the non-destructive measurement of the thickness of thin coatings on a substrate. Included therein is the utilization of a bank of memory stored data representative of isotope, substrate, coating material and thickness range characteristics in association with a control card having predetermined indicia thereon selectively representative of a particular isotope, substrate material, coating material and thickness range for conditioning electronic circuit means by memory stored data selected in accord with the predetermined indicia on a control card for converting backscattered beta particle counts into indicia of coating thickness.

Abstract: An improved gas ionization cell with compensation for variations in flow rate of the gas and variations in radioactive source intensity. A gas sample is directed past a source of ionizing radiation and through a recombination region to an ion collection screen, where output current is monitored to give an indication of trace gases or vapors present in the gas under surveillance. Compensation for changes in gas flow rate and source intensity is provided by taking a portion of the gas subjected to the ionizing radiation and directing that portion of the gas through a channel by-passing the recombination region of the cell and past a pair of conductive probes. The first probe of the pair is biased at a predetermined voltage, while electric current is monitored at the second probe spaced downstream from the first probe.

Abstract: A nondestructive system and method for the determination of the presence and extent of hydrogen embrittlement in metals, alloys, and other crystalline structures subject thereto. Positron annihilation characteristics of the positron-electron annihilation within the tested material provide unique energy distribution curves for each type of material tested at each respective stage of hydrogen embrittlement. Gamma radiation resulting from such annihilation events is detected and statistically summarized by appropriate instrumentation to reveal the variations of electron activity within the tested material caused by hydrogen embrittlement therein. Such data from controlled tests provides a direct indication of the relative stages of hydrogen embrittlement in the form of unique energy distribution curves which may be utilized as calibration curves for future comparison with field tests to give on-site indication of progressive stages of hydrogen embrittlement.

Abstract: A self-supporting portable field multichannel X-ray chemical analyzer system comprising a lightweight, flexibly connected, remotely locatable, radioisotope-excited sensing probe utilizing a cryogenically-cooled solid state semi-conductor crystal detector for fast in situ non-destructive, qualitative and quantitative analysis of elements in solid, powder, liquid or slurried form, utilizing an X-ray energy dispersive spectrometry technique.

Abstract: A method of determining a depth of an accumulation of snow in which the water-equivalent depth of an accumulation of snow is determined from the count of survival neutrons of cosmic rays after passing through an accumulation of snow.

Abstract: Apparatus and method for continuous measurement of thickness of a sheet at a rolling mill or the like without contacting the sheet. A system directing radiation through the sheet in two energy bands and providing a measure of change in composition of the material as it passes the thickness gauging station. A system providing for changing the absorption coefficient of the material in the thickness measurement as a function of the change in composition so that the measured thickness is substantially independent of variations in composition.

Abstract: Method and apparatus for measuring the concentration of various components, such as the iron component in iron ore, by exposing the material to irradiation between a neutron source and a gamma ray detector. The emitted gamma rays are captured by the detector and transformed into a signal which is transmitted to a recording device for measuring the gamma ray radiation.

Abstract: The density of a rod-like tobacco filler in a cigarette making machine is measured and regulated by placing a source of beta radiation adjacent to one side of the moving filler and a transducer at the other side of the filler opposite the source whereby the transducer furnishes a continuous series of electric signals which indicate the weakening of beta rays during passage through successive minute increments of the filler as a function of density of the corresponding increments as well as fluctuations in the intensity of beta rays due to stochastic disintegration of nuclei in the source. The signals from the transducer are integrated, either for fixed periods of time or for periods which are necessary to produce a signal of given intensity, and the thus obtained signals are used to regulate the density of the filler by controlling one or more trimming devices and/or to segregate cigarettes having fillers of unsatisfactory density.

Abstract: A method and apparatus to practice the method for rapidly determining the size and mass distribution of a sample of randomly sized particles of a known total mass. A series of substantially identical hydrocyclones are connected by conduits to each other and to a temperature controlled water feed. By restricting the cross-sectional areas of these conduits to progressively smaller values, the slurry containing the sample particles is caused to increase its velocity as it moves from hydrocyclone to hydrocyclone. As described by the Stokesian theory which relates particle diameter and settling velocity, the largest sized particles are suspended in the closed apex of the first hydrocyclone with smaller sized particles, in given size ranges, being suspended in the next succeeding hydrocyclone's apexes. In this manner, the particles are separated into discrete fractional sizes with a residual slurry of the very smallest particles being discharged.