Inline oxygenation question

[dick murton]

I've come into this discussion a little late in the day, but...

By using air, providing you can get it to dissolve the gasses, you could get about 10 ppm of oxygen in the wort at say 10 deg C (I would have to look up the gas solubility tables, which I don't have to hand at present), but could in theory achieve about 30 ppm with pure oxygen instead (I have used oxygen to get to 18 + ppm, and know of one site that uses a mixture of air and oxygen with two separate injector systems to achieve 27 ppm).

However, all of this supposes you have very fine gas bubbles and approppriate back pressure, and suitable residence time to allow the gas to dissolve.

The key to dissolving the oxygen is to get extremely fine gas bubbles in the wort using a sinter, whether it is pure air, or pure oxygen.

If you want 1000 litres wort oxygenated to 10 ppm, then you need 10 grammes oxygen = 1.08 litres pure oxygen at 1 bar pressure (22.4 litres oxygen weighs about 32 g at 0 deg C and atmospheric pressure) . In other words, it sounds like your friends are nowwhere near dissolving all the oxygen, and are in fact wasting most of it (sorry but I only have the calcs in metric - use "Convert" or similar to get to US units)

[beauxman]

Bumped this back up,

I have a DO meter and am trying to dial in my O2 rates. I seem to be having issues with finding out what a good target saturation rate would be. I have heard 1ml/L per degree plato of wort, would this be correct? I see much reference to 8-10PPM also for standard worts.

Thanks,
Beaux Bowman
Black Raven Brewing

[Roger Greene]

If I am not forgetting something, I believe 10-12 ppm is around the maximum amount you can get under the circumstances. Unfortunately O2's solubility drops with an increase in gravity, kind of unfortunate. I would say over shoot by a bit to find the max, then cut it back to that point. A little extra O2 never hurt anyone.

[BigWilley]

Does anyone pump over under pressure to get better saturation? Would it make much of a difference?

[TL Services]

Just a few notes to back up what's been said already:

dick murton is right (as ever!) that at atmospheric pressure O2 saturation is around 10ppm, perhaps a little lower dependent on temperature (higher temp = lower O2 saturation).

Around 10ppm should be fine for wort although (again like dick) I have come across much higher levels, especially in UK breweries.

Roger Greene mentions lower O2 solubility at higher gravities - this is because O2 is only really soluble in water so, as high gravity = more fermentables = less water, then the saturation level will decrease.

BigWilley - to increase saturation any pressure increase would have to be using air/oxygen to top-pressure, otherwise the gas laws dictate you would lose O2 from solution.

[Kushal]

I've heard that if you oxygenate your yeast pitch rather than your wort you can get better results and there is no chance of over oxygenation. Has anyone tried this (I have not)?

[TL Services]

I've heard that if you oxygenate your yeast pitch rather than your wort you can get better results and there is no chance of over oxygenation. Has anyone tried this (I have not)?

I've never heard of this, and would suspect it would be more likely to lead to under-oxygenation as well as possible yeast damage.