O2-ing my wort

[DJ_L3ThAL]

I'm interested to know two things:

1. Do these flow meters coming with the kits/regulators quote L/min in standard temperature and pressure units, or do they quote that as volumetric flow (ie. more actual Oxygen is going through than what is read).
   
   e.g. Oxygen dispensed at a volumetric rate of 1L/min @ 6 bar.g pressure would mean you're actually dispensing approx 6 L/min (roughly every bar pressure requires another "volume" of gas mass. So these cylinders may not last the length one would expect calculating the 1 L/min being dispensed in true S.T.P units.
   
2. Are the Tradeflame cylinders at Bunnings etc compatible with this 10mm thread on the Sealey type regulators?
   
   Side note I looked at Sealey's site and they are not designed for use with Oxygen (Only quotes CO2/Argon use) so use at your own risk. I can't find any small/cheap Oxygen regulators probably because the Oxygen cleaning would cost more than the entire value and make them too expensive.

 

[Benn]

Apparently Keg King have a complete O2 kit coming soon, pretty sure it's designed to run off the small O2 cylinders available off the shelf at Bunnings etc.
I could be mistaken, the conversation was a few weeks ago and I was in that strange state that one enters when they walk around and around a HB Shop with money to spend, no shopping list and nothing particularly needed for the brewery on the day.

 

[klangers]

I'm interested to know two things:

1. Do these flow meters coming with the kits/regulators quote L/min in standard temperature and pressure units, or do they quote that as volumetric flow (ie. more actual Oxygen is going through than what is read).
   
   e.g. Oxygen dispensed at a volumetric rate of 1L/min @ 6 bar.g pressure would mean you're actually dispensing approx 6 L/min (roughly every bar pressure requires another "volume" of gas mass. So these cylinders may not last the length one would expect calculating the 1 L/min being dispensed in true S.T.P units.

They are quoting volumetric flow rate. Since the pressure is just the back pressure of the airstone, tube and then the hydrostatic pressure of the immersion in the wort, the total pressure will be pretty close to atmospheric (standard)

 

[DJ_L3ThAL]

Completely agree that by the time the O2 makes its way through the stone into the wort it would be near atmospheric. The measurement value is in the flowmeter though, so there is a restriction across the tube and float which is typically calibrated for a certain supply pressure. You don't have atmospheric at the regulator outlet before the flow meter, I also don't think they look restrictive enough to drop the pressure from 6 bar.g to atmospheric 0 bar.g, because that in itself would infer a pretty decent flow, far above 3L/min (S.T.P).

The info on the equipment is not clear as to whether we can simply say a 110L O2 bottle will last 110minutes if running the flow meter at 1L/min flow. As the pressure of the gas will mean more O2 is going through and the bottle won't last as long. Trying to ensure some people don't run off and end up dosing at 6L/min (S.T.P) whilst thinking they are dosing 1L/min and poisoning their yeast because they are not understanding how a gas flow meter works.

 

[mofox1]

Agree Nath, that "flow meter" could just be a bit of toss. I'd be better off getting a float flow meter...

 

[Crusty]

I'm just curious as to what lag time you guys are getting before active fermentation if using an airlock & pressurized O2.
I used mine for the first time yesterday on a 50L batch of a 150 Lashes clone. I ran it for 90sec which I thought would be ample.
I planned to check on it every hour to gauge when fermentation kicked in. After the first hour, I noticed that pressure was building in the airlock & I got activity probably every 3-5 mins or so. I was initially impressed assuming that it's going to go gangbusters after a few hours. It stayed this way for the next 12hrs or so & it didn't really get a move on until about 15hrs into it. It's now 24hrs after pitching & it's really cranking along with a bloop every 5sec or so. I thought that adding the O2 should have reduced my lag time but it seems to be a similar time frame. I pitched a healthy stepped starter so had ample yeast for this batch.

 

[malt junkie]

You'll find around 3-4 hours after you initial hit of O2 the yeast will have eaten it all up, and for big beers a second hit around the 4-6 hr mark will really get it kicking. Note all this assumes a good healthy pitch of yeast etc. Oxygenation is mainly about increasing numbers.

Remember our craft and mega swill brewers pitch a ton load more yeast than we do and they still oxygenate.

 

[DJ_L3ThAL]

Crusty, O2'ed a batch last night at 7PM. Same as you within 3 hours I was thinking whoa, there is positive pressure in the blow off (by lifting the hose slightly caused some bubbles suggesting it just hadn't overcome the sanitizer liquid column. In the morning at 7am I checked when I got up and no activity. Came home tonight at 6pm and it was bubbling every 1 second which is high Krausen. Which is more than acceptable but doesn't seem "faster" than a normal healthy pitch, although I don't O2 for speed of ferment, more for yeast health and ensuring well maintained fermentation.

I concluded that perhaps given the aforementioned solubility rates, perhaps the O2 coming out of solution builds some slight pressure and gives the indication there is yeast activity where really it's just the wort dropping back to it's solubility of O2 at the given temp.

Thoughts?

 

[Lyrebird_Cycles]

You'll find around 3-4 hours after you initial hit of O2 the yeast will have eaten it all up, and for big beers a second hit around the 4-6 hr mark will really get it kicking. Note all this assumes a good healthy pitch of yeast etc. Oxygenation is mainly about increasing numbers.

Remember our craft and mega swill brewers pitch a ton load more yeast than we do and they still oxygenate.

The more yeast present the more O2 will be needed as they will need to synthesise more cell wall lipids to stay healthy.

I think there is some confusion in the HB community over what O2 does.

Adding O2 helps yeast adapt to growth in the inhospitable anaerobic environment that is a fermenting wort. We don't usually add enough O2 to promote aerobic (respiratory) growth rates.

Oxygen is used to make lipids and the lipids are required for growth, so oxygen will promote growth but there's a lag while the yeast use the oxygen to make the lipids they need.

The other benefit of O2 is at the back end of fermentation: having a healthy cell wall allows the yeast to stay alive in the presence of a toxin (alcohol) which primarily works by knocking chunks out of the lipid bilayer and causing the contents of the cell to leak.

BTW that's also how alcohol works in your brain and liver: it makes the cells slightly leaky. Brain cells change the way they talk to each other, liver cells change the way they sieve fats out of the bloodstream.

 

[Crusty]

So basically I too misunderstood the benefits of using O2. If we pitch a good healthy starter with sufficient yeast cells, adding O2 simply gives the yeast more oxygen to use to multiply which in turn builds up their numbers. They can simply reproduce in the presence of oxygen & once those levels drop, active fermentation begins. Shorter lag times shouldnt be expected then? Once fermentation begins, it should be more aggressive & may finish earlier than a non oxygenated wort but will have the benefit of a stronger cleaner ferment?
Am I on the right track here?

 

[Lyrebird_Cycles]

I concluded that perhaps given the aforementioned solubility rates, perhaps the O2 coming out of solution builds some slight pressure and gives the indication there is yeast activity where really it's just the wort dropping back to it's solubility of O2 at the given temp.

Thoughts?

I don't think that would be the case, as far as I am aware almost all the O2 that goes into solution is absorbed by either oxidation reactions in the wort or taken up by the yeast. I cannot see the solubility equilibrium shifting to release oxygen that was already in solution.

 

[peteru]

adding O2 simply gives the yeast more oxygen to use to multiply which in turn builds up their numbers.
...
Am I on the right track here?

I don't think so. I think the point is that the yeast will multiply regardless of the oxygen level. More O2 will make the yeast more healthy, which means that they will not die as quickly and more importantly their metabolism will be healthier, thus resulting in fewer fusel alcohols and other off-flavours.

 

[Lyrebird_Cycles]

Crusty, Peteru, I steered you wrong in the first version of post #109 by not clarifying the effect of oxygen on lipids and the subsequent effect on growth. My apologies, I've corrected it now.

 

[peteru]

Right. That bit about lipids now also makes more sense in the context of trying to introduce fatty acids so that the yeast doesn't have to do as much work on that task.