View Full Version : DO meter or air tester?

Alley Kat
01-14-2005, 09:04 PM
We have money in our lab budget to purchase either an air tester or a do meter. We bottle beer at our brewery so an air tester would be very useful, but I'm wondering if I can use a do meter to give me similar qc information as it would also provide some useful information up-stream from the bottler. Any opinions?


Alex T
01-15-2005, 08:21 PM

i think that you require both - suprised that you don't already have a DO meter for wort aeration checks and filtration purposes. might be playing with fire quality-wise. think you had better find a way to purchase both.

if you check only head space air, you may find that they are OK, but you don't know if you are sending high DO beer to the bottle in the first place.

if you check only DO, that may be great, but you may be oxidising the beer due to high air in package.

hmmm, maybe someone else has a way use only one instrument for both purposes?????



Sir Brewsalot
01-15-2005, 08:35 PM
Well, I suppose you could shake up the bottle, and dissolve any oxygen into the beer, and test for it there - maybe after it has a minute to settle?


Alley Kat
01-16-2005, 08:48 AM
That's what I am thinking might work as a poor brewer's air tester. In the end isn't an increase in total disolved oxygen the result of high (or for that matter any) head space air?


dick murton
01-17-2005, 02:54 AM
If you only have money for one, get yourself an oxygen meter for in line analysis.

For crude (but actually surprisingly accurate for quick assessment) testing air in headspace, as soon as the bottle has been crowned, turn the bottle on it's side. If all the gas bubbles are fine, and of even size, say under 1 or 2 mm diameter, then chances are you haven't picked up much oxygen. If you have one or more large bubbles - these indicate air. The more large bubbles - the more air you have entrained - so you need to turn up your pre crowner fobbing unit.

Simple ! Hope this helps


01-17-2005, 08:49 AM
With a budget for only one tester, we chose an air tester. With an optional sample bottle, you can check the air levels in your bright tank then in your package, allowing you to check air pickup during the packaging. If you're concerned about consistent carbonation levels in package, then a DO meter won't help much anyway.

If you package in cans or kegs you won't be able to do the murton "crude air" test.

01-17-2005, 09:31 AM
Here's a novel idea: buy, beg, borrow, or steal a copy of the latest ASBC method on testing for dissolved oxygen in the package, otherwise known as Total Package Oxygen. With this method and a portable DO meter in hand, you can McGiver yourself a pretty accurate idea of how much oxgyen is in the head space and how much is dissolved in the beer.
The air method is really not all that accurate it turns out.........

Alley Kat
01-17-2005, 09:46 AM
Originally posted by tallmatt67
With an optional sample bottle, you can check the air levels in your bright tank then in your package, allowing you to check air pickup during the packaging.

How do you check the air levels in bright beer using the optional bottle? I was under the impression that the air tester just tested for head space air and, secondarily, CO2 levels. As for checking CO2 levels in bright beer, we use a Zahm SS-60 CO2 meter (the kind that you fill from a sample cock and then shake).

Regarding the Murton test, do you let the fob in the bottle settle at all before this test, or do you do it right away?


01-17-2005, 09:49 AM
If only buying one unit then I would suggest the purchase of a dissolved oxygen (DO) meter.
1) Head space air tester (HSAT) using a caustic shake test is slow labor intensive procedure and a rough number (user dependent) and not accurate compared to a good DO meter.

2)HSAT will only tell you how much air you put in the bottle in packaging, but not how much had been added during processing (which has reacted with the beer before packaging and thus not available to be measured by either type).

3) HSAT is not practical for testing inline/tank samples. Assuming that you could sample in a representitive way, I would argue that doing caustic shake tests would be cumbersome and impractical to use for regular basis monitoring that a packaging brewery needs to be doing. The DO meter will allow you to perform an audit of your whole process and allow routine monitoring of processes.

4) The DO meter can be used with a piercing device for cans or bottles allowing measurement of actual DO in liquid.

5) The DO meter will also let you control wort aeration/oxygenation

Out of all the analysis equipment that I use in the brewery by far the DO meter is the most used and depended upon for my operation. I would say that if you are packaging beer that you really must have one. If oxygen is not in control your great beers will be destroyed quickly.

I have happened to use only Orbisphere meters and I am very happy with them. Mettler-Toledo is also a provider of units.

If you can not afford a DO tester then consider the HSAT as a stop gap.

Hope that helps.

Alley Kat
01-17-2005, 09:57 AM
Great idea. I had (incorrectly) assumed that the disolved oxygen test in the ASBC's Laboratory Methods for Craft Brewers was the only disolved oxygen test. Does anyone have an idea where I might find a copy of the method for DO in packaged beer (US$529 is outside of my budget!).


01-17-2005, 02:12 PM
Sure ASBC website has it,

In this document they discuss the factors involved in determining Total Package Oxygen(TPO)(sometimes TI("in")PO). TPO is a relative number based on many factors that you can see listed in the document. Head space air is also a relative measurement so you don't need to be concerned about trying to convert DO or TPO to head space air.

If testing head space air then try to attain the lowest possible results, typically less than .5ml and definitely less than 1.0 ml (per 331-355ml package).

For TPO I have seen specs ranging from 80pbb up to 200ppb. For a 331-355 package typically the TPO is ~double the measured O2.

I have never seen a correalation chart between head space air and DO/TPO.

Also note that in this document they mention the portable 3650 Orbisphere units being used for package DO measurements. While they did give higher values than the purpose built machine the numbers are still close and certainly more accurate than the HSAT method.


Hope that helps.

01-17-2005, 04:56 PM
If you're going to spend up to $6,000 for a new portable orbisphere DO meter what's and extra grand to purchase a HSAT? I'd get both if I were you. The orbisphere can be used to check package DO's but requires more equipment and a Nitrogen source to push beer through the orbisphere for accurate DO's. Luckily this can be an "add on" feature should the price jump up too much for the allotted budget.

If you're currently checking CO2 levels in the bottle using the Zahm device they have additional parts you could purchase and add on to check headspace airs, may save you a little $$.

dick murton
01-18-2005, 08:23 AM
Re the very rough air in headspace check - no don't let it settle at all. The check needs to be made within a few seconds of the bottle being discharged from the crowner. A long delay between crowning and inspection may give a false result. If the foam bubbles are very fine, say less than 1 mm, the foam ia more stable and you will have longer to check. But the bubbles start to coalesce immediately and are liable to give a false result. Pick them off the line as soon as it is physically safe to do so.


Alley Kat
01-18-2005, 08:28 AM
Thanks to all that posted. Your comments have been very helpful. I've decided to go the DO meter route, although I don't think that I'll be getting an Orbisphere! I should be able to "McGyver" a less pricey DO meter to do the test outlined in the ASBC link.