Abstract: In both the method and system for clearing the debris from the aperture of a particle study device combinations of pulses of predetermined, waveform amplitude and frequency are developed and coupled through the conductive fluid passing through the particle study device aperture. The pulses cause the fluid in the aperture to vaporize and form a gas. The gas explodes away any debris clogging the aperture as it escapes from the aperture.

Abstract: An automatic diluting device draws and dispenses a volume of sample along with a volume of diluent so as to maintain a precise ratio between the volume of sample and the volume of diluent. The device includes a diluent chamber having a plunger therein which is reciprocable between a first and second position for displacing a first volume therein when moved, and at least a first sample chamber having a plunger therein reciprocable between a first and second position for displacing a second volume therein when moved. The first and second volumes are arranged to have a fixed precise ratio with respect to one another for any equal distance moved by said first and second plungers in their chambers. A coupling device couples the plungers together for simultaneously reciprocally moving the plungers an equal distance in the chambers between first and second positions.

Abstract: A particle separator for separating particles suspended in a fluid according to certain characteristics, including a device for adjusting an electrical delay to be equal to the time between the emergence of a particle from a jet forming aperture to the point of break-off. The device includes a variable scale graticule coupled to a potentiometer.

Abstract: The pulse amplitude discriminating circuit is utilized in a system where particles in a fluid are caused to flow through a sensing zone and a particle pulse is generated for each particle sensed with the amplitude of each pulse being related to the size of the particle sensed. The discriminating circuit is operative to determine which pulses have an amplitude falling between predetermined upper and lower amplitude levels, for remembering each pulse while the determination is being made and for passing to a pulse analyzing circuit only the pulse heights of those remembered pulses which have an amplitude falling between the predetermined upper and lower amplitude levels.

Abstract: A particle analyzer for obtaining a narrow distribution of particles suspended in a liquid wherein electric pulses are produced by moving the liquid through a sensing zone. The analyzer includes elements for differentiating the pulses, short circuiting to ground pulse portions of one state and measuring the heights of pulse portions of another state as indications of particle sizes.

Abstract: A method for the elimination of sample turbidity in blood serum samples where the turbidity is caused by the presence of chylomicrons, by forming an interface between the sample and a fat specific solvent, centrifuging the thus prepared unit and thereafter either decanting the solvent or withdrawing the cleared serum.

Abstract: The photometer circuit is operative to receive and store a reference voltage which is generated in a photosensor by light which passes through a blank solution in a cuvette and is received at the photosensor. The photometer circuit includes reference voltage input control circuitry for placing the photometer circuit in a receiving and storage mode of operation for a predetermined period of time while the reference voltage is being generated in the photosensor. The photometer circuit includes a comparator having two inputs, a first electronic switch for coupling the output of the comparator to a voltage storage circuit and a second electronic switch for coupling the output of the voltage storage circuit to a voltage run-down circuit.

Abstract: By creating at least two related raw counts N.sub.1 and N.sub.2, of particles in a fluid suspension either as two physcially derived particle counts, or one physical count and an artificial count derived from the physical count, there can be developed a mathematic function relationship by which the "scanning constant" K of a particle analyzer, for example of a Coulter type, can be factored out and a resultant equation obtained. The resultant equation is employable in operating upon the input N.sub.1 and N.sub.2 raw counts for generating the ultimately desired corrected particle count N.sub.0, which eliminates particle coincidence errors. The disclosure encompasses several methods and apparatuses by which the raw counts are developed and by which the related mathematic functions are defined and then employed to obtain corrected counts.

Abstract: By creating at least two related raw counts n and n.sub.i, of particles in a fluid suspension as at least two physically derived particle counts, there can be developed a mathematic function relationship by which the "scanning constant" k of a particle analyzer, for example of a Coulter type, can be factored out and a resultant equation obtained. The resultant equation is employable, for instance, in operating upon the input n and n.sub.i raw counts for generating the ultimately desired corrected particle count N.sub.i which largely eliminates particle coincidence errors. The disclosure encompasses several methods and apparatuses by which the raw counts are developed and by which the related mathematic functions are defined and then employed to obtain corrected counts. Specially considered are multichannel analysis and optical apparatus for facilitating the count correction.

Abstract: The electrical sensing circuitry includes a power supply and a signal-detecting circuit which are coupled through the resistance of an electrolyte in a liquid in an aperture of a particle-analyzing device between sensing electrodes positioned on either side of the aperture. The liquid containing an electrolyte and the passage of a liquidborne particle through the aperture causes a change in the resistance of the aperture thereby generating a signal which is detected by the signal-detecting circuit. The parameters of the circuit elements are chosen to provide circuit relationships which render the particle-generated signal independent of the diameter of the aperture. This is achieved by utilizing a power source having a low output impedance and a signal-detecting circuit which has a low input impedance for both D.C. and A.C., namely, at the signal frequencies of the signals sensed.

Abstract: An apparatus for determining the correct particle sizes at predetermined percentiles of the size distribution of a particulate system having a known size distribution characteristic such as for example a normal or log-normal size distribution, wherein a portion of the particles are too small to be measured. The particulate system is first passed through a particle detecting device which can be of the Coulter type. The particle detecting device produces particle pulses proportional to the size of the particles in the particulate system which can be measured. At least three percentile size determining circuits receive the particle pulses and develop first, second and third particle size signals respectively, indicating the size of the particles in the particulate system at the first, second and third predetermined percentiles.

Abstract: A particle analyzer of the Coulter type has at least one sensing zone arrangement for generating a first train of particle pulses having a first number of particle pulses in response to passage through the sensing zone of a sample containing a plurality of particles to be counted. Generating circuitry is provided for generating a second train of particle pulses having a second number of particle pulses based upon a second sample containing a plurality of particles, or a hypothetical second sample. The second sample has a specific relationship to the first sample defined by one of either the first and second sample volume ratios, the first and second sample dilution ratio and the sensing zone volume ratio.

Abstract: A particle study device includes a sample metering device having an input for receiving a sample of particulate matter, a drain for expelling the sample of particulate matter, an ejection port, and means for trapping a volume of sample within the device. The sample metering device also includes an ejecting device operative to eject a predetermined amount of the trapped sample through the ejecting port. A coupling device coupled to the sample metering device, a source of diluent and the sensing zone in the particle study device, combines the ejected predetermined amount of particulate matter and diluent to form a liquid suspension and couples the liquid suspension to the sensing zone.

Abstract: A method and apparatus are disclosed wherein each particle pulse developed in response to passage of particles in a particulate system through a sensing zone is integrated to develop a first voltage whose amplitude varies in accordance with the number of pulses. The pulses are also integrated to develop a second voltage whose amplitude varies in accordance with the duration and, therefore, the size of all of the particle pulses. The first and second voltages are multiplied together to yield an error corrected voltage representing an error corrected particle pulse count, which is then converted to an error corrected particle pulse count.

Abstract: An apparatus which includes circuitry for automatically sampling each pulse in a series of pulses a predetermined average number of times, sequentially storing the samples for a period of time, and reproducing the pulses from the samples, delayed in time.A method of operation is encompassed within the invention as well as use of the above apparatus in a particle study device.

Abstract: A particle study apparatus which in response to passage of particles in suspension through a sensing device produces electrical pulses which are proportional in amplitude to the size of the respective particles. The apparatus includes a system for ascertaining the particle size above and below which size predetermined fractions of one of the total mass and total number of the particles in suspension are respectively included. If total mass is desired electrical quantities are accumulated in response to each electrical pulse which are proportional to the amplitudes of the electrical pulses. If total number is desired constant electrical quantities are accumulated in response to each electrical pulse. The electrical quantities are designated as being in one of two categories depending upon whether the electrical pulses producing same are greater than or less than a variable threshold.

Abstract: A method and apparatus for automatically generating error corrected pulses in response to particle pulses which are subject to error due to coincidence. The subject apparatus includes a generator for generating error corrected pulses which has a variable pulse repetition rate controlled via an applied variable control signal. A pulse duration modifying circuit receives the particle pulses and develops first pulses each having a duration equal to a predetermined function of the duration of a particle pulse. A control circuit receives the error corrected pulses and develops a second signal in response thereto. The development of the second signal via the control circuit is inhibited in response to the presence of first pulses coupled thereto from the pulse duration modifying circuit. A comparison circuit develops the control signal which varies in accordance with the difference between the repetition rate of the particle pulses and the third signal.

Abstract: A method and apparatus for correcting a particle pulse count subject to coincidence error is disclosed wherein particle pulses, developed in response to passage of particles in a particulate system through a sensing zone, are counted for a predetermined period of time. The predetermined period of time is increased or extended in response to each pulse counted by a time increment that is a function of a characteristic of the counted pulse, such as the pulse width, duration, or amplitude. The total additional time period allows the counting of additional particle pulses such that the total count at the end of the extended time period is an error corrected count for the number of particles detected in the predetermined time period.

Abstract: A pneumatically controlled liquid transfer system for delivering a liquid from a source to a delivery location, said liquid source being provided with a pneumatic cylinder for driving the liquid from said source, a pneumatically operated pinch valve of the make-before-break type and flexible conduit paths leading through the valve to the delivery location. The make-before-break pinch valve comprises a valve shell having two pistons movable laterally therein. The shell has a window. One piston has a yoke, each arm thereof having a passageway, one aligned with the other. A stop extends between the arms of the yoke. One of the flexible conduits is arranged through the window between the first piston and the yoke and the other flexible conduit is arranged also through the window but within the aligned passageways and between the piston and post. The second piston is spring biased to bear against the second conduit to place same in a normally closed condition. The first conduit is normally open.

Abstract: An apparatus used in a particle measuring device where liquid suspensions of particles to be measured are brought into contact with the apparatus. The apparatus includes an aperture tube and a thief conduit which are secured to one another and form a unitary structure. The unitary structure has its exterior surface constructed and arranged so as to minimize contamination via carry over from one suspension to another.