Self-cleaning aperture tube for coulter study apparatus

Claim 2

In a particle measuring apparatus including a container of particulate liquid suspension to be tested, an aperture tube extending into said container, a vacuum source for moving the liquid from the container into and through the aperture tube, a first electrode in the container and a second electrode in the aperture tube to establish an electrical field between said container and the aperture tube, and a detector, the aperture tube having a first and a second chamber, the first chamber having an aperture in communication with the liquid suspension in the container, said second chamber having an orifice provided therein at a point closely spaced from and directly opposite the interior of said aperture, means connecting said second chamber to said vacuum source and means to initially fill the first chamber with particle free liquid and the second chamber with the liquid suspension, the improvement comprising, a conduit extending between said chambers to provide a closed path for liquid flow therebetween, a pump interposed in said conduit to create liquid flow about said path, and a filter member in said conduit, whereby the suspension will flow from the container through the aperture and the orifice into said second chamber to mix with the liquid already therein and circulate about said path, said filter member removing the particles from the liquid before the same is returned to the first chamber.

Claim 3

The structure as claimed in claim 1 in which an elongate neck extends from the second chamber into the first chamber and said orifice is provided in said neck.

Claim 4

An aperture tube for use in particle measuring apparatus including a container of particulate liquid suspension into which the aperture tube extends, said tube including a first and a second chamber, the first chamber having an aperture in communication with the liquid suspension, said second chamber having an orifice provided therein at a location directly opposite the interior of said aperture, means for connecting said second chamber to an external source of vacuum, conduit means extending between said chambers to provide a closed path for liquid flow therebetween, a pump interposed in said conduit means to create liquid flow about said path, and a filter member in said conduit means, whereby the suspension will flow through said aperture in the first chamber and through said orifice in the second chamber and then through said conduit and said pump and said filter member where the particles from the suspension are removed before the same is forced into the first chamber and returned through said orifice.

Claim 5

An aperture tube for use in particle measuring apparatus including a container of particulate liquid suspension into which the aperture tube extends, said tube including a first and a second chamber, the first chamber having an aperture in communication with the liquid suspension, said second chamber having an orifice provided therein at a location directly opposite the interior of said aperture, means for connecting said second chamber to an external source of vacuum, conduit means extending between said chambers to provide a closed path for liquid flow therebetween, a pump interposed in said conduit means to create liquid flow about said path, and a filter member in said conduit means, whereby the suspension will flow through said aperture in the first chamber and through said orifice in the second chamber and then through said conduit and said pump and said filter member where the particles from the suspension are removed before the same is forced into the first chamber and returned through said orifice.

Claim 6

An aperture tube as claimed in claim 3 in which an elongate neck extends from said second chamber into said first chamber and said orifice is provided in said neck.

Claim 7

In a particle measuring apparatus which responds to the changes of electrical impedance due to the displacement of electrolyte by particles suspended therein in an aperture which constricts an electric field, including a container of liquid suspension to be tested, a dual-chamber aperture tube having a first and a second chamber extending into said container, a vacuum source for moving the liquid from the container into and through the aperture tube, a first electrode in the container and a second electrode in the aperture tube to establish the electric field, and a deTector, the first chamber having an aperture forming a communication between said container and said first chamber, the second chamber having an orifice forming a communication between said first and said second chambers, said orifice being positioned close to and directly opposite said aperture, the improvement comprising, means for preventing particles from the contents of the container from being transferred to suspension in the contents of the first chamber.

Claim 8

In a particle measuring apparatus which responds to the changes of electrical impedance due to the displacement of electrolyte by particles suspended therein in an aperture which constricts an electric field, including a container of liquid suspension to be tested, a dual-chamber aperture tube having a first and a second chamber extending into said container, a vacuum source for moving the liquid from the container into and through the aperture tube, a first electrode in the container and a second electrode in the aperture tube to establish the electric field, and a deTector, the first chamber having an aperture forming a communication between said container and said first chamber, the second chamber having an orifice forming a communication between said first and said second chambers, said orifice being positioned close to and directly opposite said aperture, the improvement comprising, means for preventing particles from the contents of the container from being transferred to suspension in the contents of the first chamber.

Claim 9

The structure as claimed in claim 5 in which said means comprises a conduit extending between said chambers to provide a closed path for liquid flow therebetween, a pump interposed in said conduit to create liquid circulation about said path, and a filter for removing particles from the circulating liquid, such that the volume of liquid which flows into said orifice is the sum of the circulation about said closed path plus the flow from said container into said first chamber.

Claim 10

The structure as claimed in claim 6 in which said vacuum source is adapted to withdraw liquid from the low pressure side of said pump.

Claim 11

The structure as claimed in claim 7 in which an elongate neck extends from the second chamber into the first chamber and said orifice is provided in said neck.

Claim 12

The structure as claimed in claim 7 in which filling means are provided to fill the aperture tube, said conduit and said pump with liquid prior to performing the first test of particle suspension contained in said container.

Claim 13

The structure as claimed in claim 9 in which said filling means comprise a two-way stopcock and an open-close stopcock, said two-way stopcock being adapted to apply vacuum either to said first or said second chamber or to neither, said open-close stopcock being adapted to connect one chamber to a reservoir of suspension liquid.

Claim 14

The structure as claimed in claim 10 in which an elongate neck extends from the second chamber into the first chamber and said orifice is provided in said neck.

Claim 15

In a particle measuring apparatus including a vessel for containing a body of particulate liquid suspension to be tested, an aperture tube extending into said vessel and including an aperture, fluid moving means for establishing pressure differentials and adapted for moving the suspension from the vessel through the aperture into and through the aperture tube to a waste collection container, a first electrode in the vessel and a second electrode in the aperture tube to establish an electrical field in the aperture between said vessel and the aperture tube, means including electrical leads connected to the electrodes and adapted to extend connections to a detector to respond to electrical measuring signals produced across said electrodes with passage of particles through said aperture, the aperture tube having an inlet chamber adapted for fluid connection with a source of particle free liquid, said inlet chamber having said aperture in fluid communication on one side thereof with the suspension in the vessel to permit passage of the suspension through the aperture into the inlet chamber, there being a zone in the aperture tube proximate to and downstream of the aperture in which spurious signals may normally be produced, an outlet chamber in fluid connection with said inlet chamber, means for connecting said outlet chamber to said fluid moving means and said waste collection container, means for initially filling the inlet and outlet chambers with particle free liquid; the improvement comprising, said aperture tube having a restriction in the path of flow of said particle free liquid to cause the flow velocity thereof to increase in the spurious signal producing zone and continuously to wash the zone simultaneously with passage of the suspension through the aperture such that particles which have been measured within the aperture while the apparatus is in use for measuring particles and the means for initially filling the inlet and outlet chambers are rendered inoperative and thereafter passing out of the same immediately are swept out of the spurious signal producing zone by the particle free liquid and moved into the outlet chamber.

Claim 16

In a particle measuring apparatus including a vessel for containing a body of particulate liquid suspension to be tested, an aperture tube extending into said vessel and including an aperture, fluid moving means for establishing pressure differentials and adapted for moving the suspension from the vessel through the aperture into and through the aperture tube to a waste collection container, a first electrode in the vessel and a second electrode in the aperture tube to establish an electrical field in the aperture between said vessel and the aperture tube, means including electrical leads connected to the electrodes and adapted to extend connections to a detector to respond to electrical measuring signals produced across said electrodes with passage of particles through said aperture, the aperture tube having an inlet chamber adapted for fluid connection with a source of particle free liquid, said inlet chamber having said aperture in fluid communication on one side thereof with the suspension in the vessel to permit passage of the suspension through the aperture into the inlet chamber, there being a zone in the aperture tube proximate to and downstream of the aperture in which spurious signals may normally be produced, an outlet chamber in fluid connection with said inlet chamber, means for connecting said outlet chamber to said fluid moving means and said waste collection container, means for initially filling the inlet and outlet chambers with particle free liquid; the improvement comprising, said aperture tube having a restriction in the path of flow of said particle free liquid to cause the flow velocity thereof to increase in the spurious signal producing zone and continuously to wash the zone simultaneously with passage of the suspension through the aperture such that particles which have been measured within the aperture while the apparatus is in use for measuring particles and the means for initially filling the inlet and outlet chambers are rendered inoperative and thereafter passing out of the same immediately are swept out of the spurious signal producing zone by the particle free liquid and moved into the outlet chamber.

Claim 17

The invention as claimed in claim 12 in which said fluid moving means comprise a source of vacuum.

Claim 18

An aperture tube for use in particle measuring apparatus including a container of particulate liquid suspension into which the aperture tube extends, said tube comprising, an inlet chamber, an outlet chamber in fluid connection with the inlet chamber, the inlet chamber having an aperture adapted to be in communication on one side thereof with the liquid suspension, there being a zone in the aperture tube proximate to and downstream of the aperture in which spurious signals may normally be produced, means for connecting the inlet chamber to a source of particle free liquid, means for directing flow of said particle free liquid from said source into and through said inlet chamber and thereafter into and through said outlet chamber, means for connecting the outlet chamber to fluid moving means to move the suspension from the container through the aperture into the spurious signal producing zone while said particle free fluid is so flowing, the tube having a restriction in the path of flow of the particle free liquid to cause the flow velocity thereof to increase in the spurious signal producing zone and continuously wash the zone simultaneously with passage of the suspension through the aperture such that particles which have passed through the aperture immediately are swept out of the spurious signal producing zone by the particle free liquid and moved into the outlet chamber.

Claim 19

An aperture tube for use in particle measuring apparatus including a container of particulate liquid suspension into which the aperture tube extends, said tube comprising, an inlet chamber, an outlet chamber in fluid connection with the inlet chamber, the inlet chamber having an aperture adapted to be in communication on one side thereof with the liquid suspension, there being a zone in the aperture tube proximate to and downstream of the aperture in which spurious signals may normally be produced, means for connecting the inlet chamber to a source of particle free liquid, means for directing flow of said particle free liquid from said source into and through said inlet chamber and thereafter into and through said outlet chamber, means for connecting the outlet chamber to fluid moving means to move the suspension from the container through the aperture into the spurious signal producing zone while said particle free fluid is so flowing, the tube having a restriction in the path of flow of the particle free liquid to cause the flow velocity thereof to increase in the spurious signal producing zone and continuously wash the zone simultaneously with passage of the suspension through the aperture such that particles which have passed through the aperture immediately are swept out of the spurious signal producing zone by the particle free liquid and moved into the outlet chamber.