Wort Aeration with Oxygen

[gregorach]

The arithmetic seems OK, but zero wastage is definitely not a safe assumption - not at that flow rate anyway. The actual amount of O2 that gets into solution will depend on a number of factors, including flow rate, the depth of wort the gas is passing through, the size of the bubbles, and the temperature. I would much rather go with figures determined by actual measurement in homebrew type equipment, even second hand, than some theoretical calculation based on obviously false assumptions.

[barneey]

Just one more question (I promise), could you tell me your current brew size for the 1ltr per min for 60 seconds.

AND.... If you are going for a fully enclosed future system are you purging the FV with anything before the wort enters it?
Many Thanks

Clive

[gregorach]

Just one more question (I promise), could you tell me your current brew size for the 1ltr per min for 60 seconds.

20 - 22 L.

AND.... If you are going for a fully enclosed future system are you purging the FV with anything before the wort enters it?

No.

[Aleman]

I've used an Inline system with O2 where the diffuser sits in a T and the wort passes over it, apart from the problems of excessive foaming, when I actually measured the O2 concentration in the wort it was well over 20ppm at which point it becomes toxic to yeast (That is 2L/min for the 20 minutes it took to transfer the wort for the kettle though the chiller to the FV) . . I did swap to Sterile filtered air from a compressor (still at 2L/min) and got down to a nice 14ppm O2 for the same transfer time (But still had the foam issue to deal with)

I have gone back to O2 since getting the Conical fermenter, but I simply pass the tube into the conical via the blow off tube and allow it to run at 2L/min for 5 minutes before starting the cool wort transfer which hits a spray plate in the FV causing much reduced foaming and a larger surface area for gas exchange. This produces a wort with around 12ppm O2 (as measured), and I can actually turn off the O2 during transfer as the reducing head space becomes oxygen enriched.

Unfortunately my access to a good DO meter is very sporadic

[barneey]

Hi Aleman,

What was the volume of wort being aerated @2Ltr per min for 5 mins?

Thanks

[Aleman]

I start the O2 flow before any wort flows into the Conical, just to increase the partial pressure of O2 in the conical. I then transfer 80-90L of wort to the conical in about 15 minutes, in general theO2 flow remains constant during wort transfer, but I normally cut it off once I get 60-75 litres of wort in the FV.

[barneey]

In the absence of being able to get my hands on dissolve oxy meter and not having a spray plate in the FV, I`ve gone for Dunc`s approach of a stainless airstone feeding oxygen through the wort.

For my 40 / 45ltr brew batch I`ll try out 1litre per min for 120 seconds.

[barneey]

Finally the new regulator arrived today so now have everything I need to get started, just need to cut a piece of gas line for the connection between the flow and the airstone.

Air flow is very easy to control from zero onwards.



Now to wait for another brewday

[Highlander]

How do you fit the air stone? Do you just drop it in.

In my head, with the conical you could take a drilled swagelok compression fitting onto beer line (beer line right the way though) with the air stone on the inside and hook it up to to the bottom tap(what ever connection you have on it. Open the valve, dose with 02 close the tap and remove.
Or is that complicating it?

[barneey]

I have thought about making a more permanent fixture of the thing, but for the time being its a straight forward "drop it in approach".

Less additional fittings to clean + air stone can be lifted out and not left in the FV.

[gregorach]

How do you fit the air stone? Do you just drop it in.

In my head, with the conical you could take a drilled swagelok compression fitting onto beer line (beer line right the way though) with the air stone on the inside and hook it up to to the bottom tap(what ever connection you have on it. Open the valve, dose with 02 close the tap and remove.
Or is that complicating it?

If you immerse the stone without gas blowing through it, it will fill with wort and clog.

[Martin G]

We used to use the Winkler method, might be possible to find a kit for this a bit for a bit less than a DO meter. It is a faf, but I guess once set up you follow the method rather than test every time.

[Highlander]

If you immerse the stone without gas blowing through it, it will fill with wort and clog.

So long as you turn the gas on before opening the valve.

Another cheaper option(no need for a regulator flow meter). Though no where near as exact. Fill the FV with o2, then use the sprayer/defuser on the end of the wort hose?,

Just don't smoke at the same time

[Martin G]

Anyone ever tried using an NT labs Dissolved oxygen test kit? They cost about £15. They are designed for ponds, so despite no online seller publishing the detection range, you would expect it to be about the same as what we are interested in. The bigger risk is that the wort interferes with the test. I suppose tests could be carried out on tap water that has been left open over night to lose the chlorine.

http://www.ingslane.com/NT-Labs-Test-Ki ... p-144.html

[barneey]

Interesting test kit, would really need a member with a "dissolve oxy meter" to test it first to see if it was a viable alternative.