Conductivity sensor assembly
View Patent ↗A flow-through conductivity sensor assembly comprises a housing ( 4 ) having a flow passage with an inlet end and an outlet end. The cross section of at least a section of the flow passage extension between the inlet and outlet ends is divided into a conductivity measuring channel ( 2 ) and a parallel by-pass channel ( 3 ) of larger cross-sectional area than the measuring channel ( 2 ).
1. A flow-through conductivity sensor assembly for bio-process flows, comprising a housing ( 1 ; 50 ) having a flow passage ( 51 ) with an inlet end and an outlet end, wherein the cross section of at least a section of the flow passage extension between the inlet and outlet ends is divided into a conductivity measuring channel ( 2 ; 53 ) and a parallel by-pass channel ( 3 ; 51 a ) of larger cross-sectional area than the measuring channel, wherein the conductivity measuring channel ( 2 ; 53 ) is placed in the cross-section of the by-pass channel ( 3 ; 51 a ), wherein a first and a second electrode are provided adjacent to a respective end of the measuring channel and wherein a first electrode ( 4 ; 55 ) is provided within the measuring channel ( 2 ; 53 ) and a second electrode ( 5 , 6 ; 54 , 56 ) is provided adjacent to one or each end of the measuring channel ( 2 ; 53 ).
2. The conductivity sensor assembly of claim 1 , wherein the cross-section of the measuring channel ( 2 ; 53 ) is at least substantially circular.
3. The conductivity sensor assembly of claim 1 , wherein the measuring channel is disposed adjacent to the inner periphery of the flow passage.
4. The conductivity sensor assembly of claim 1 , wherein the second electrode ( 54 , 56 ) is disposed within the measuring channel ( 53 ).
5. The conductivity sensor assembly of claim 1 , comprising annular electrodes ( 5 , 6 ; 54 - 56 ).
6. The conductivity sensor assembly of claim 5 , wherein the electrodes are made of metal.
7. The conductivity sensor assembly of claim 5 , wherein the electrodes surround a liquid path through the measuring channel.
8. The conductivity sensor assembly of claim 1 , wherein the ratio of the cross-sectional area of the measuring channel ( 2 ; 53 ) to the cross-sectional area of the by-pass channel ( 3 ; 51 a ) is less than about 1:2, preferably less than about 1:4, more preferably less than about 1:10, for especially less than about 1:30.
9. The conductivity sensor assembly of claim 1 , wherein the by-pass flow channel is divided into at least two separate flow paths.
10. The conductivity sensor assembly of claim 1 , further comprising a pH probe ( 43 ; 80 ) exposed to fluid flowing in the flow passage ( 51 ).
11. The conductivity sensor assembly of claim 10 , wherein the pH probe ( 80 ) extends into the by-pass channel ( 51 a ).
12. The conductivity sensor assembly of claim 10 , wherein the housing ( 50 ) is a single-piece unit.
13. The conductivity sensor assembly of claim 12 , wherein at least the measuring electrode is provided by an electrode element ( 55 ) mounted in a recess ( 58 ) extending through the housing ( 50 ) transversely to the measuring channel ( 53 ).