Self priming conductivity cell

Claim 2

For use in a system for counting particles suspended within a liquid, a conductivity cell comprising: a cell body having an input passage therein adapted to be coupled to a supply of liquid to be analyzed, and an output passage therein adapted to be coupled to a tube through which said liquid flows during an analytical run; a support member having an aperture provided therein, said support member being removably disposed within said cell body with said aperture having one end in alignment with the input passage of said cell body and an opposite end in alignment with the output passage of said cell body; first and second electrodes respectively disposed in said input passage and said output passage and confronting respective ends of said aperture; means for providing electrical connection from said first and second electrodes to respective terminals on said cell body; a vent passage within said cell body communicating with said output passage at a position near said aperture; a bubble chamber communicating with said input passage and operative to collect gas bubbles present in said liquid in a position removed from said aperture such that said gas bubbles are not drawn through said aperture during analysis; and priming means including a valve mechanism, a first passage communicating between said valve mechanism and said bubble chamber, and a second passage communicating between said valve mechanism and a priming output port, said priming means being operative with said valve mechanism in a first position to prevent fluid flow through said first and second passages to said priming output port, and operative with said valve mechanism in a second position to allow fluid flow through said first and second passages to said priming output port.

Claim 3

The invention according to claim 1 wherein said valve mechanism includes means operative to actuate an electrical switch associated with said cell.

Claim 4

The invention according to claim 1 wherein said valve mechanism includes: an elongated opening in said cell body; a plunger slidably disposed in said elongated opening; means for sealing said plunger within said opening; and at least one channel provided in said plunger and positioned and constructed to permit said plunger in said second position to permit fluid communication between said first and second passages.

Claim 5

The invention according to claim 3 wherein said valve mechanism includes spring means for urging said plunger into said first position in the absence of an actuating force applied thereto.

Claim 6

The invention according to claim 1 wherein said aperture is disposed coaxially in said support member and said support member includes a passage therein communicating between said one end of said aperture and said input passage.

Claim 7

The invention according to claim 5 further including a baffle plate disposed in said cell body within said output passage in a position confronting said opposite end of said aperture, said baffle plate having openings therethrough and operative to minimize the effects of spraying and turbulence of liquid emanating from said aperture.

Claim 8

The invention according to claim 1 wherein said aperture is disposed within a wall of said support member with said one end in coNfronting relation with said input passage.

Claim 9

The invention according to claim 1 wherein said cell body includes a transparent window in a surface thereof confronting said bubble chamber and operative to permit viewing of said chamber.

Claim 10

The invention according to claim 8 wherein said transparent window is a lens for magnified viewing of said bubble chamber.

Claim 11

The invention according to claim 1 wherein said support member is of transparent material and said aperture is disposed coaxially therein, the end of said support member external to said cell body having a window provided in the surface thereof for viewing of said aperture along the axis of said support member.

Claim 12

The invention according to claim 10 wherein said window is a magnifying lens to provide magnified viewing of said aperture.

Claim 13

The invention according to claim 1 wherein said support member is of transparent material and said aperture is disposed coaxially therein, with a transverse passage communicating with said one end of said aperture and said input passage, the end of said support member external to said cell body having a window therein for viewing of said aperture along the axis of said support member.

Claim 14

The invention according to claim 12 wherein said support member includes a section external to said cell body detachably connected to a section including said aperture, said aperture-containing section having a coaxial opening therein communicating between said one end of said aperture and the end of said section confronting said external section to permit cleaning of said aperture with said aperture-containing section detached.

Claim 15

The invention according to claim 1 wherein said priming means is operative with said valve mechanism in said second position to permit air flow from said vent passage, aperture, and bubble chamber through said first and second passages to said priming output port for backflushing of said aperture.

Claim 16

For use in a system for counting particles suspended within a liquid, a conductivity cell comprising: a cell body having an input passage therein adapted to be coupled to a supply of liquid to be analyzed, and an output passage therein adapted to be coupled to a tube through which said liquid flows during an analytical run; first and second electrodes respectively disposed in said input passage and said output passage and operative to provide an electrical current therebetween with liquid in said passages; means for providing electrical connection from said first and second electrodes to respective terminals; a support member removably disposed within said cell body and having an aperture in said support member disposed with one end in alignment with said input passage and an opposite end in alignment with said output passage; a vent passage within said cell body communicating between the atmosphere and said output passage at a position near said aperture; a bubble chamber within said cell body communicating with said input passage and operative to collect gas bubbles present in said liquid in a position removed from said aperture such that said gas bubbles are not drawn through said aperture during analysis; and priming means including a valve mechanism, a first passage communicating between said valve mechanism and said bubble chamber, and a second passage communicating between said valve mechanism and a priming path which is of lower hydraulic impedance than the path provided by said input and output passages of said cell body; said cell being operative with said vent passage closed and said valve mechanism in a first position to allow fluid flow through said input and output passages and said aperture, and operative with said vent passage closed and said valve mechanism in a second position to allow fluid flow through said first and second passages to said priming output port, and operative with said valve mechanism in said second position and said vent passage open to allow the passage of air iNto said vent passage, through said aperture and thence through said first and second passages to said priming output port.

Claim 17

For use in a system for counting particles suspended within a liquid, a conductivity cell comprising: a cell body having an input passage therein adapted to be coupled to a supply of liquid to be analyzed, and an output passage therein adapted to be coupled to a tube through which said liquid flows during an analytical run; first and second electrodes respectively disposed in said input passage and said output passage and operative to provide an electrical current therebetween with liquid in said passages; means for providing electrical connection from said first and second electrodes to respective terminals; a support member removably disposed within said cell body and having an aperture in said support member disposed with one end in alignment with said input passage and an opposite end in alignment with said output passage; a vent passage within said cell body communicating between the atmosphere and said output passage at a position near said aperture; a bubble chamber within said cell body communicating with said input passage and operative to collect gas bubbles present in said liquid in a position removed from said aperture such that said gas bubbles are not drawn through said aperture during analysis; and priming means including a valve mechanism, a first passage communicating between said valve mechanism and said bubble chamber, and a second passage communicating between said valve mechanism and a priming path which is of lower hydraulic impedance than the path provided by said input and output passages of said cell body; said cell being operative with said vent passage closed and said valve mechanism in a first position to allow fluid flow through said input and output passages and said aperture, and operative with said vent passage closed and said valve mechanism in a second position to allow fluid flow through said first and second passages to said priming output port, and operative with said valve mechanism in said second position and said vent passage open to allow the passage of air iNto said vent passage, through said aperture and thence through said first and second passages to said priming output port.

Claim 18

The invention according to claim 15 further including means for regulating electrical current applied to said electrodes to compensate for variations in liquid conductivity and aperture area, said means comprising: a difference circuit having one input coupled to said electrodes and operative to sense a change in current flow between said electrodes and to provide an error signal representative of said change; a reference source for providing a reference current to a second input of said difference circuit, said reference current being of a magnitude equal to an intended current between said electrodes for a predetermined liquid conductivity and aperture area; an integrator coupled to said difference circuit and operative to provide a correction signal in response to an error signal provided by said difference circuit; and resistor means for coupling said correction signal to said electrodes to adjust the electrode current to a magnitude at least substantially equal to said reference current.

Claim 19

For use in a system for counting particles suspended within a liquid, the combination comprising: a conductivity cell including a liquid path having an aperture therein through which particle-containing liquid is caused to flow and a pair of electrodes on respective opposite sides of said aperture operative to sense the electrical impedance of the liquid path and to provide electrical pulses in response to the passage of particles through the aperture; means for regulating the electrical current applied to said electrodes to compensate for variations in liquid conductivity and aperture area, said means including: a difference circuit having one input coupled to said electrodes and operative to sense a change in voltage drop across said electrodes and to provide an error signal representative of said change; a reference source for providing a reference current to a second input of said difference circuit, said reference current being of a magnitude equal to an intended current between said electrodes for a predetermined liquid conductivity and aperture area; an integrator coupled to said difference circuit and operative to provide a correction signal in response to an error signal provided by said difference circuit; and resistor means for coupling said correction signal to said electrodes to adjust the electrode current to a magnitude which tends to reduce the error signal to zero.

Claim 20

For use in a system for counting particles suspended within a liquid, the combination comprising: a conductivity cell including a liquid path having an aperture therein through which particle-containing liquid is caused to flow and a pair of electrodes on respective opposite sides of said aperture operative to sense the electrical impedance of the liquid path and to provide electrical pulses in response to the passage of particles through the aperture; means for regulating the electrical current applied to said electrodes to compensate for variations in liquid conductivity and aperture area, said means including: a difference circuit having one input coupled to said electrodes and operative to sense a change in voltage drop across said electrodes and to provide an error signal representative of said change; a reference source for providing a reference current to a second input of said difference circuit, said reference current being of a magnitude equal to an intended current between said electrodes for a predetermined liquid conductivity and aperture area; an integrator coupled to said difference circuit and operative to provide a correction signal in response to an error signal provided by said difference circuit; and resistor means for coupling said correction signal to said electrodes to adjust the electrode current to a magnitude which tends to reduce the error signal to zero.

Claim 21

For use in a system for counting particles suspended within a liquid, a conductivity cell comprising: a cell body having an input passage therein adapted to be coupled to a supply of liquid to be analyzed, and an output passage therein adapted to be coupled to a tube through which said liquid flows during an analytical run; a support member having an aperture provided therein, said aperture having one end in alignment with the input passage of said cell body and an opposite end in alignment with the output passage of said cell body; first and second electrodes respectively disposed in said input passage and said output passage and confronting respective ends of said aperture; means for providing electrical connection from said first and second electrodes to respective terminals on said cell body; a vent passage within said cell body communicating with said output passage at a position near said aperture; a bubble chamber communicating with said input passage and operative to collect gas bubbles present in said liquid in a position removed from said aperture such that said gas bubbles are not drawn through said aperture during analysis; and priming means including a valve mechanism, a first passage communicating between said valve mechanism and said bubble chamber, and a second passage communicating between said valve mechanism and a priming output port, said priming means being operaTive with said valve mechanism in a first position to prevent fluid flow through said first and second passages to said priming output port, and operative with said valve mechanism in a second position to allow fluid flow through said first and second passages to said priming output port.

Claim 22

For use in a system for counting particles suspended within a liquid, a conductivity cell comprising: a cell body having an input passage therein adapted to be coupled to a supply of liquid to be analyzed, and an output passage therein adapted to be coupled to a tube through which said liquid flows during an analytical run; a support member having an aperture provided therein, said aperture having one end in alignment with the input passage of said cell body and an opposite end in alignment with the output passage of said cell body; first and second electrodes respectively disposed in said input passage and said output passage and confronting respective ends of said aperture; means for providing electrical connection from said first and second electrodes to respective terminals on said cell body; a vent passage within said cell body communicating with said output passage at a position near said aperture; a bubble chamber communicating with said input passage and operative to collect gas bubbles present in said liquid in a position removed from said aperture such that said gas bubbles are not drawn through said aperture during analysis; and priming means including a valve mechanism, a first passage communicating between said valve mechanism and said bubble chamber, and a second passage communicating between said valve mechanism and a priming output port, said priming means being operaTive with said valve mechanism in a first position to prevent fluid flow through said first and second passages to said priming output port, and operative with said valve mechanism in a second position to allow fluid flow through said first and second passages to said priming output port.