Cell Constant of a Commercial Graphite Probe
Estimating the cell constant of an Oakton(tm) conductivity probe available from Cole-Parmer.
An Oakton™ conductivity probe is available from Cole-Parmer (PN EW-35820-62). The data on this page is provided so that you may use an Oakton™ conductivity probe to meter the conductivity or ion concentration in your own fluid instrumentation applications.
The probe uses parallel graphite electrodes and incorporates a 100Ω RTD. The electrodes are approximately planar – 1cm long, 2 mm wide, and separated by 5 mm. From geometrical considerations1) we would expect an upper limit on the cell constant to be,
Owing to fringing fields beyond the region directly between the electrode plates the cell's conductance is greater and the actual cell constant is lower. Cole-Parmer specifies the cell at K = 1.0 cm-1
The cell's 10 foot cable is terminated with the following wires:
| Color | Connection |
|---|---|
| white | conductivity electrode |
| black | conductivity electrode |
| green | RTD compensating wire (high) |
| red | RTD high |
| brown | RTD return |
| clear | shield wire |
See also → Conductivity Sensing Wildcard