Conductivity Measurement

Dec 31, 2005 6 Replies
N

Hi,



I recently bulit a Conductivity Meter for my project, initially the conductivity was displayed as per the cell constant set by me, but over a few days the conductivity displayed is reasonably dropped by about 5 Siemens. I found that if i took the Dieelectric liquid in a small volume vessel the conductivity was properly shown. But when i used a comparatively large vessel the conductivity drops dowm by 5 Siemens. Area wise the two vessels are 1:1000 times approx.



I am using a AC generator section of 1Khz @ 2.8 VAC.



thanks in advance guys...



Vote
Twitter Facebook LinkedIn
J

It's probably NOT 4-point ;-)

...Jim Thompson

| James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC\'s and Discrete Systems | manus | | Phoenix, Arizona Voice:(480)460-2350 | | | E-mail Address at Website Fax:(480)460-2142 | Brass Rat | | http://www.analog-innovations.com | 1962 | "Winners never quit, quitters never win", Jack Bradley Budnik ~1956
Vote
Twitter Facebook LinkedIn
K

I assume you had a question you forgot to include.

How much total voltage are you applying to the sample in each case? Is the temperature constant and uniform?

What % change are you seeing?

Do the batteries in your meter need changing? (Once bitten)

-- kensmith@rahul.net forging knowledge
Vote
Twitter Facebook LinkedIn
G

Or perhaps his electrode geometry is such that conductivity outside of the electrodes, "fringing" of sorts, is significant in the larger vessel but cut off by the vessle walls in the smaller vessel. Small electrode area and relatively large spacing would cause this. Concentric electrodes with spacing very small compared to area would minimize it. It would seem impossible to entirely eliminate fringing (and some attendant sensitivity to vessel shape) without a closed sample cell.

Vote
Twitter Facebook LinkedIn
N

hi,

I am using a transformer to convert 230VAC to 18 VAC and then convert it to 15vdc. i am using a wein bridge oscillator for ac generation section.. please suggest.

the change i am observing is of 5Siemens...

Best regards...

Vote
Twitter Facebook LinkedIn
N

hi,

I am using a transformer to convert 230VAC to 18 VAC and then convert it to 15vdc. i am using a wein bridge oscillator for ac generation section.. please suggest.

the change i am observing is of 5Siemens...

Best regards...

Vote
Twitter Facebook LinkedIn
K

[...]

Or about 50 other things. Without far more detailed description of what he's doing, it is worthless to try to figure it out.

-- kensmith@rahul.net forging knowledge
Vote
Twitter Facebook LinkedIn

Join the Discussion

Have something to add? Share your thoughts — no account required.

Didn't find your answer?

Ask the community — no account required