The value indicated by the meter when measuring low conductivity samples such as pure water, semiconductor cleaning water, boiler water, tap water, groundwater, river water, or rainwater, is generally unstable. This is because such samples have very few impurities, so the measurements are easily affected by stains in the sample container or carbon dioxide in the surrounding atmosphere.
The following methods can provide measurements that are more accurate:
Measurement using a flowing sample (flow-through system)
Submersible Type Cell
- A submersible-type cell (#3551-10D) with a cell constant of 10 m-1(0.1 cm-1) (for low conductivity water) is prepared.
- A flow measurement container (see figure) is made.
- The entire cell is inserted into the shielded box and the measurement is performed. (It is best to wait for sometime until the meter displays a stable value).
Measurement of flowing sample using a submersible-type cell
- A flow-type cell (#3561-10D) with a cell constant of 10 m-1(0.1 cm-1) (for low-conductivity water) is prepared.
- Tubes are attached to the inlet and outlet of the conductivity cell and sample liquid is fed through it, as seen in the below diagram.
- A nitrogen purge of the sample tank prevents the sample from coming into contact with air.
Measurement of flowing sample using a flow-type cell
Use a clean airtight container and purge it with nitrogen or argon gas
- A submersible-type cell (#3551-10D) with a cell constant of 10 m-1(0.1 cm-1) (for low-conductivity water) is prepared.
- The sample is purged with nitrogen or argon to prevent it from coming in contact with air.
- The measurements should be performed in a shielded box as they are vulnerable to external electrical noise and should be taken only when the meter indicates a completely stable value.
- The liquid is stirred slowly at 300 rpm to decarbonize it.
This information has been sourced, reviewed and adapted from materials provided by HORIBA Scientific.
For more information on this source, please visit HORIBA Scientific.