mr x
Well-Known Member
I had e-mailed Wyeast regarding this oxygenation theory. Some people may find this info useful:
I am about to get an O2 aeration system and have a couple of questions.
When you figure 1 min of O2 into 5 gallons will give 12ppm, is that from
a wort at 0ppm, or does that include a base level in the wort of maybe 4
ppm from splashing into a carboy?
Can you estimate the absorption rate of the O2 into the wort? I did some
math to come up with these numbers:
12ppm(or mg/L) of O2 into 20L of wort requires 240 mg of O2.
Converting this to moles O2 (32 g/mole) I get .0075 moles O2.
Using an ideal gas law assumption (22.4 liters/mole), I get a required
volume of pure O2 of .168L - or 0.0059 Cubic feet. required for 12 ppm.
To inject the O2 for 1 minute through a stone, I would think you must be
using very low pressure, or a lot of O2 is lost. Is that correct?
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Thank you for the email.
The oxygenation time is based on starting with <1ppm DO.
I do not have an absorption rate for O2 into wort as there are many
variables involved including stone surface area, pore size, wort volume,
wort temperature, wort gravity, and pressure. The largest problem (in
my opinion) with efficiently dissolving oxygen into wort is the surface
area of the stone with respect to the volume of wort. The optimal
method for dissolving O2 in to wort is to pass the wort stream past a
stone in line, post heat exchanger, similar to most commercial
breweries. This insures a high ratio of stone surface area to wort
volume.
To finally answer you question, a lot of O2 is lost.
I have been using a different method of injecting O2 into the headspace
and then shaking the carboy for 30 seconds. I am achieving good DO
levels (approx 12ppm) when doing this twice.
I hope that this helps.
I am about to get an O2 aeration system and have a couple of questions.
When you figure 1 min of O2 into 5 gallons will give 12ppm, is that from
a wort at 0ppm, or does that include a base level in the wort of maybe 4
ppm from splashing into a carboy?
Can you estimate the absorption rate of the O2 into the wort? I did some
math to come up with these numbers:
12ppm(or mg/L) of O2 into 20L of wort requires 240 mg of O2.
Converting this to moles O2 (32 g/mole) I get .0075 moles O2.
Using an ideal gas law assumption (22.4 liters/mole), I get a required
volume of pure O2 of .168L - or 0.0059 Cubic feet. required for 12 ppm.
To inject the O2 for 1 minute through a stone, I would think you must be
using very low pressure, or a lot of O2 is lost. Is that correct?
-------------------------------------------------------------------------------------------------------------
Thank you for the email.
The oxygenation time is based on starting with <1ppm DO.
I do not have an absorption rate for O2 into wort as there are many
variables involved including stone surface area, pore size, wort volume,
wort temperature, wort gravity, and pressure. The largest problem (in
my opinion) with efficiently dissolving oxygen into wort is the surface
area of the stone with respect to the volume of wort. The optimal
method for dissolving O2 in to wort is to pass the wort stream past a
stone in line, post heat exchanger, similar to most commercial
breweries. This insures a high ratio of stone surface area to wort
volume.
To finally answer you question, a lot of O2 is lost.
I have been using a different method of injecting O2 into the headspace
and then shaking the carboy for 30 seconds. I am achieving good DO
levels (approx 12ppm) when doing this twice.
I hope that this helps.
