Coulter Electronics, Inc.

Coulter International Corp.

Harvey J Dunstan

Marshall Donnie Graham

John Geoffrey Harfield

Ted W Britton

Ervin Fayer

George G Dominick

Ian D Gilbert

Avelino De Oliveira

Henry Howard Gulliford

James S King

Harvey J Podgorney

Gerry Graham

Paul Knight

Apparatus for sensing and characterizing particles suspended in a liquid medium includes a particle-sensing structure having a continuous wall defining a hydrodynamically smooth conduit through which the liquid suspension of particles is caused to pass simultaneously with an electrical current. Particles passing through the conduit are sensed and characterized by monitoring changes in the electrical current through the conduit. According to the invention, the continuous, conduit-defining wall is made entirely of a material having an electrical resistivity less than or equal to that of the liquid medium. Thus, the apparatus of the invention is similar to the conventional Coulter aperture (conduit) except that the aperture is formed from an electrically conductive material instead of a dielectric material.

Apparatus incorporating a sensing conduit in conductive material and method of use thereof for sensing and characterizing particles

A Coulter apparatus comprises a volumeter assembly containing a conduit through which a particle suspension is caused to pass simultaneously with an electrical current. In preferred embodiments the volumeter assembly comprises at least one traditional Coulter conduit wafer, i.e., a dielectric wafer containing a central circular conduit, and at least two electrically conductive collars. The conductive collars approximate the conduit diameter in thickness, are uninsulated, and are attached to opposite sides of the conduit wafer, the openings being congruent with the Coulter conduit. The Coulter conduit in the dielectric wafer and the openings in the conductive collars collectively form a hydrodynamically smooth conduit, in which the electric and hydrodynamic fields of the Coulter conduit are amended. The electric field is shaped to confine the particle-sensitive zone of the novel volumeter conduit within the conduit's physical boundaries, thereby decreasing the zone's coincidence volume. The hydrodynamic field is caused to develop quasi-laminar flow, thereby increasing the proportion of particles per second transiting the zone's electrically homogeneous areas. The conductive collars are provided with electrical connections and also function as electrodes, used either in a passive mode to allow potential-sensing of particle characteristics or in an active mode in response to such particle characteristics. The volumeter assembly substantially eliminates need to compensate for the effects of particles either transiting the sensitive zone on trajectories near the conduit wall or recursing through the exit portion of the particle-sensitive zone.

Potential-sensing method and apparatus for sensing and characterizing particles by the Coulter principle

A solenoid operated pinch valve including a housing and a hollow molded body coupled to said housing by a snap-on connection, a solenoid coil assembly seated within the housing, a plunger accommodated within said solenoid coil assembly for axial movement relative thereto controlled by energization of said solenoid coil assembly and between a pair of positions, said plunger having an end portion extending from the housing into said body and an opposite end portion received within said solenoid coil assembly, the body having a circumferential flange capable of being seated on one end of the housing and a pair of inflexible arms extending from the body in a coaxial direction relative thereto, said arms defining a passage for receiving a conduit across the path of movement of said plunger, a first orthogonal slot and a pair of resilient arms extending to the opposite end of the housing and engagable therewith in a snap-on coupling. One end of the plunger carries a second orthogonal slot. A flexible conduit having longitudinal ears unitary therewith is threadable thorugh the passage with the ears engaged within said orthogonal slots. A spring is provided for biasing the plunger against the flexible conduit to compress same closed, the solenoid coil assembly being energizable to move the plunger linearly against said bias by causing the plunger to pull the conduit open.

Snap-together solenoid operated pinch valve assembly

Method and apparatus for editing particle produced electrical pulses

Method and apparatus for providing a concentration study of particles in a large system of continuously flowing fluid which is coupled to a sampling chamber that has a detector of the Coulter type therein. A regulator is provided to maintain constant the pressure in the sampling chamber irrespective of pressure changes in the large system. The regulator establishes a boundary surface between fluid from the sampling chamber and a column of liquid, such as mercury, immiscible with said fluid and of greater density than said fluid; whereby, a predetermined pressure is produced at said surface and permits sample fluid to pass through said column liquid as the pressure on the fluid variably exceeds the pressure at the boundary surface.

On-line sampling system for monitoring particles suspended in a fluid

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Herts, United Kingdom

Harvey J Dunstan