Adjust the head space or blow it out with inert gas.

Ray

"Joe Ae" > wrote in message
.. .
> Hi Ray
>
> Thanks for bring light to this risk. After reading your post I placed a 12
> Gal DJ for cold stabilization. I left about and inch of headspace. The
> temperature in my MLF area is 70F and in the garage it is 40F. I was
amazed
> at how much volume contraction occurred.
>
> I am wondering whether I should now adjust the headspace or leave it for
the
> 3-4 weeks it will take to cold stabilize?
>
> Joe
>
> "Ray" > wrote in message
> y.com...
> > A few days ago, under a thread with the banner "Wine Aging" I made some
> > comments about the effect of temperature on the ability of airlocks to
> > protect wine. I promised to post more later.
> >
> > Air locks are designed to be a constant pressure valve to protect the
> wine.
> > Of course during fermentation CO2 is given off, the pressure in the
vessel
> > tries to go up and the excess volume bubbles out through the airlock.
> > Perfect. If the temperature of bulk aging wine increases, the wine
> expands,
> > pressure tries to goes up, and what ever is in the head space bubbles
out
> > through the airlock. Fine. If the wine expands too much and all the
head
> > space is expelled, then wine goes out through the airlock. Not so fine.
> > You can watch your wine you can prevent this.
> >
> > But if the temperature drops too much, a different scenario takes place.
> > Outside air will bubble through the airlock into the carboy. If this
> > happens it is not a very good thing. So how much protection does an
> airlock
> > provide and how important is this?
> >
> > I checked two types of airlocks. The S shaped airlock with three bubble
> > chambers on each side will hold 11 cc's of liquid when properly filled.
> The
> > 3 piece cylindrical airlock will hold 9 cc's from bottom of the floating
> > valve to where liquid spills through the tube so it provides 9 cc's of
> > protection. (I did not have one of the S locks with one chamber on each
> > side free to test.) For this analysis I will use the 9 cc smaller
airlock
> >
> > The question now is how much of a temperature change will these volumes
> > protect against before air bubbles through the airlock. This is
effected
> by
> > the volume of the wine and the starting temperature. I assume 25 deg C
as
> > the starting temperature and determined the temperature drop the airlock
> > will protect against for different size carboys. I found the following:
> >
> > Carboy Temp Drop
> > (US gal) (deg C)
> > 1 9.7
> > 3 2.2
> > 5 2.0
> > 6 1.2
> > 10 0.8
> > 12 0.7
> > 13 0.6
> >
> > This shows some pretty small numbers, but what are the restrictions of
the
> > calculation.
> > 1) I used the expansion of water. I found the expansion table for
> alcohol
> > but not for 13% alcohol, so I considered water to be a better estimate.
I
> > suspect that wine will have more expansion and therefore less protection
> but
> > I can not say for certain.
> > 2) I do not make a correction for expansion of the glass vessel but
this
> > should be very small.
> > 3) This is based on temperature changes of the wine, not the room.
Over
> a
> > one day/night temperature cycle the room may change more than the wine.
> > (Thanks to Jack Keller for pointing this out.)
> >
> > Now what does this mean? Standard airlocks will protect carboys of 5-6
> gal
> > or smaller from temperature changes in a temperature controlled home and
> may
> > well protect the larger carboys. But if you are keeping wine in an
> > unairconditioned room or in a cellar that sees temperature changes of
> > several degrees C. You may want to take all this into account.
> >
> > You should be aware of day to night temperature changes, changes
> associated
> > with cold fronts, and seasonal changes. Seasonal changes, though they
may
> > cause the largest change will probably not be too important as there
will
> > only occur once a year. Day night changes may not be important as the
> wine
> > may not change temperature fast enough to matter. But if it does it
will
> be
> > catastrophic as it will happen 365 times a year. Changes associated
with
> > cold fronts and heat waves may be the ones you really have to be
concerned
> > about.
> >
> > Ray Calvert
> >
> >
> >
>
>