Dissolved oxygen table

[dick murton]

I am looking for two tables. The first is one prepared by Krauss, I think in the late 70's, which tabulates the level of dissolved oxygen in wort at 12 degrees plato, when saturated with air at 760mm Hg, at a range of different temperatures. I have one or two figures, but would like a copy of the complete table. I can find loads of tables with air saturated water, but less oxygen dissolves in wort, and I want a copy of the Krauss table to give me an accurate picture.

The second one is a table of dissolved oxygen in wort, when oxygen is dissolved in water (or ideally, wort). I know if you multiply the air figure by five, it will be reasonably close, but again, I would like the complete table, assuming anyone has prepared such a beast. I have two figures, for values at 0 C and 20 C, the multiplication factor for these two is not quite the same, and I know the solubility curve is not a straight line

Can anyone help please? Thanks

[crassbrauer]

I have a lot of literature in German, but I unfortunately don't think I've come across the graphs you're referring to before (Krauss originally published in German, I assume?). I do have some simple XL graphs depicting the coefficient of the solubility of oxygen and other common gases in 1 kg of water at 1 bar of pressure at temperatures ranging from 0 - 20 C, which should be close. As you mentioned, you probably already have this information, though. (The coefficient of oxygen solubility is 41.5 at 5C, 36.8 at 10C and 33.0 at 15C, which is the range you'd probably be wanting.)

I think oxygen levels in wort aren't subject to an extreme amount of scrutiny, because it's almost impossible to be very accurate with it, since most breweries aerate their wort as it's being pumped into the fermenter (the pressure isn't constant in this case). Therefore, a little more is generally pumped in to get the ballpark figure of 25 - 40 liters of air/hl.

[dick murton]

Thanks for the comments. I picked up the reference to Krauss in Moll, "Beers & Coolers", along with values for wort at zero, 5, 10, 15 & 20 C. As you say, from his name, I assume his mother tongue is/was German.

When you say "The coefficient of oxygen solubility is 41.5 at 5C, 36.8 at 10C and 33.0 at 15C..." please clarify for me. Is this the solubility of pure oxygen in equilibrium with wort or water, or is there an equation to go with it ? I have a figure of around 69 ppm in water at zero C, and if I remember correctly (the exact figures are at work) about 43 ppm at 20 C, which is far higher than the 32 ppm (approx) I have previously been led to believe can be achieved.

I am interested in the graphs of pure oxygen solubility in water if you are prepared to send them on / attache them. Thanks

And by the way - Moll has references to trub flotation with air. Having done all the British brewing exams, this technique was never mentioned once - so I guess I owe you an apology for my scepticsm. Now where have I heard the word insular mentioned about the English before ??!!

Cheers

[dick murton]

I have at last found the original article by Krauss published in the 11th EBC proceedings. This only gives dissolved oxygen data for wort at zero, 5, 10, 15 & 20 C. I suspect there were no other details published by him - but if anyone knows otherwise, please let me know

Thanks

[crassbrauer]

I'm sorry, I've been away from internet access for a little while, so I've just seen your posts. I'm not at home, so I'll get back with you Monday. If you want, send your email address to texbrew@gmx.net, and I can mail you the graphs (pdf files of XL documents). Thanks for the info on Krauss.

[imabrewer]

Hi Dick,
Any chances of getting a copy of that chart from you or a web link to it? Sounds like a good chart to have on hand and I couldn't find anything about it while searching the web after reading your last post. Thanks

Curtis

[jason.koehler]

I'd be interested in seeing it also...

[beertje46]

From crassbrauer:


Luft = air

technische Loeslichkeitskoeffezient =
technical solubility coefficient

Wasser = water

Temperatur = ...I think you can figure this one out

[dick murton]

Thanks guys.

I will post the Krauss derived graph a little later, as it is at work, not at home.

Cheers

[GarySped]

Oxygen tables.

Yes, Mr. Murton the Tables should be of use to many. Thanks for the offer to post. I look forward to seeing it/them.

Gary.

[dick murton]

OK, here it is. I have also made a point about using oxygen meters in the attachment. Basically it seem no-one worries about the difference in wort oxygen results when using an instrument calibrated in air or water, because at the end of the day, if a fermentation is slow, you bump up the oxygen, if it produces too much yeast, you reduce it a little. The key parameter is obtaining consistency. But is does tell you why you need oxygen not air when the yeast needs more than single figures of oxygen (ppm)

I tried to put in a chart of oxygen solubility in water, but the file size is just too big to be allowed as an attachment here. But to get one, just go into google and enter "Oxygen solubility" and you will find any number of variations. There are minor differences between them for some reason, but not enough to be critical.

Cheers all

[Szymon Tochman]

Dear All,

With pure oxygen injection I can easily go above 15ppm in high gravity wort (for more than 12% Plato) at 10 Celsius degrees, in-line, measurement about 40m after Venturi pipe.
That is why I look at those Mr. Krauss table with a manner of little doubt.

And there is something I must say to you, my friends. In my opinion it is impossible to calculate the right oxygen concentration in high fermentors. As the concentration vary according to the hydrostatic pressure and top part barrier occur inside, no proper homogenisation is possible inside the mass of liquid. The problem is particularly visible when bottom fermented lager is farmenting.

Even the precise mass-flow based oxygen dosing can give you sometime a day without humour!

Take care.
st

[Szymon Tochman]

I forgot...

Maybe it would be useful to find table that shows solubility in water and in wort at different temperatures and different pressures.

Have a nice time.

[dick murton]

The yeast mops up the oxygen pretty quickly - fast enough that it is impossible to accurately measure DO2 in pitched wort in FV with any degree of reliability. The best thing to do is to use a mass flow meter, or at least calculate the mass flow according to pressure and flow rate into the wort stream. If you have a really effective mixer unit, the venturi systems such as manufactured by Esau & Hueber, amongst others is being used increasing for larger scale operations, then a few meteres of pipe work will normally get the oxygen completely dissolved. If you put a back pressure control valve in as well, then this will increase the rate of solution. At the levels brewing yeast needs, you don't need any more than the amount (pure oxygen only)that can dissolve at atmospheric pressure. In fact some people claim oxygen around 30 ppm actually harms most yeasts - not sure why though as this detail wasn't mentioned.

It is generally claimed that 30 ppm DO2 can be achieved in wort with pure oxygen, and 10 - 12 with air

Cheers