Jeff Chorniak ) wrote:
>135 gallons is a lot of weight already on the inside wall, pushing outwards.
>We're naturally assuming that the wall is thick enough to withstand the
>pressure of that weight from within. Therefore, we're also assuming the
>amount of low pressure on the upper air surface (created by the gentle pump)
>is minimal (just enough to draw trapped gasses to the surface and suck them
>out: it only takes a -1 lb/sq in. less than ambient over a period of several
>hours to do the trick), while the actual weight of 135 gallons of fluid
>keeps the outward pressure on the wall to prevent collapse (implosion).

>Even so, Lum's posting below probably has a point if you're already using a
>transfer pump. If you're racking or transferring with gravity (as some
>wineries do), then a pump may still be an alternative option, in the way Lum
>mentioned.

>Whatever pump you choose, it will be a good idea to research the physics of
>it all (and maybe experiment with a tank of water first).

>Jeff

I've seen collapsed tanks in wineries where the winemaker forgot to
open the tank before pumping out of it. I wouldn't try to de-gas
that way.

In some instances I have had to de-gas large volumes of wine, in
particular rieslings which were not fermented completely dry, and so
were kept at 35F or so from the time they reached the residual sugar
I wanted, normally in October or November until February or March
when I bottled them. If the wines have too much residual CO2,
they're really hard to bottle, so the way we de-gassed them was to
open the top of the tank, run a hose from the bottom valve to the
pump (with a rubber impeller moving the wine), and then another
hose in the top of the tank and back into the wine. We'd then pump
the wine until the impeller no longer drove CO2 out of solution.


Dave
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Dave Breeden