Continuous measurement of CO2 dissolved in water


Thread Starter

Roger Johnsen

I am looking for some industrial equipment for continuous measuring of CO2 level in a watertank. I've only been able to find instrument for use in labs.

I need this in order to document quality in a process line (food industry). I would be thankful if anyone can tip me where to find the type of equipment or info I am looking for :)

Bob Peterson

I could envision a system where a small sample of the water in the vessel is passed through and RO membrane and the product is tested with a conductivity monitor. Should give you some idea where you are at, but is not perfect.

Michael Turnbull

Have you thought about using an online PH device? Reason is that CO2 levels in water are related to PH.

That is - as the CO2 level increases the PH drops and as the CO2 level decreases the PH increases. The reason is that CO2 forms carbonic acid in water thereby effecting PH.

The Foxboro company make industry leading online PH probes. This solution may be a possibility for you to consider.

Idealy you would take the PH measurement into a PLC or DCS. For a given PH measurement the PLC or DCS could provide a lookup value of the CO2 which then could be trended or displayed on your MMI.

Good luck

Michael Turnbull

Matthew Hyatt

Try looking up disolved oxygen meters or similar insturments, these are very common in water treatment and waste water treatment applications.

Pickup a Cole-Parmer catalog, Omega, Hach or try searching for water quality instrumentation, CO2 meters.

Good luck.
My company manufactures O2 and CO2 analyzers. Our market is primarily the fruit storage industry, where apples, pears, and other products are stored in a low oxygen environment for up to a year. CO2 must be monitored since the fruit consumes O2 and gives off CO2 as a product of respiration. If left uncontrolled, the CO2 will build up to a level that will damage the fruit. If you would like to inquire about our analyzers, please contact me at: [email protected].
Just what the doctor ordered...

See EID's CO2 Gas sensing ISE Electrode at:

For interface board between your voltmeter/PLC/ADC and the electrode:

1. For one probe:

2. For dual probes:

3. Application note:
Appl. note #39

If you aould like to measure and log the mV of the electrode directly to the PC via E-USB, look at the following URLs:

A. Appl. note #36

B. Appl. note #33

Good luck,

YSI (Yellow Springs Instruments) makes a dissolved CO2 analyzer commonly used in biotech fermentation processes.