Tips for Getting Accurate Portable Dissolved Gas Measurements


My last post was about getting accurate in-line gas measurements. There is a link to that post here. Today I’m going to follow-up with some tips on how to achieve accurate portable results.

Portable measurements are a tad more forgiving and easier to accomplish than in-line measurements. You don’t have as many sensor placement restrictions and you can measure in vessels, as opposed to using an in-line probe that needs flow. Here are the main things to remember:

  1. Just as with in-line probes, all of the gasses in your beer — the CO2 and O2 that will be in contact with the sensors — need to be clear and in solution. If there is degassing in the flow chamber then you will probably get lower than expected results.
  2. Even though you are not measuring in-line, you still need to deal with flow in the flow chamber of your instrument. Portable electrochemical oxygen sensors have specified flow rates. If you deliver the sample too slowly or too quickly, the readings will be underestimated. Slow flow will not feed sufficient product to the sensor to satisfy the requirements of the sensor’s electrochemistry. High flow may result in product degassing.
  3. Optical sensors are much more forgiving and require less flow than electrochemical sensors. The instruments used with most optical probes are designed to free you from worry about flow as long as there’s sufficient backpressure on the systems to keep them from degassing.

My final thought is to remember that different analyzers have different functions, and you may need more than one to instrument to get full control over your dissolved gasses. You can’t go wrong with a good electrochemical analyzer, but optical sensors give you a different type of flexibility, and might be the next step in a well-rounded instrument collection.

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