deaerated water

[sleeper]

I have just started working with a vertical leaf filter system. one of the things that concerns me is the water push out at the end of the filter cycle. deaerated water has been thrown around as a solution. how does one go about deaerating water? how long will the water be deaerated? ect, ect.

[dick murton]

A number of different methods are used. The simplest is to sparge a tank of water with oxygen free CO2 or nitrogen, using a sinter to ensure fine bubbles of gas. Sparge until the dissolved oxygen is as low as you need. More complex systems use a series of two or three tanks each with a sparge fitted, the water flowing from one to another. This uses slightly less gas and generally gets lower dissolved oxygen levels. I have seen 100000hl / annum breweries use two 10 hl tanks in series and get good results, running them virtually continuously.

Still more complex systems use inert packing to trickle the water over and increase the surface area for gas interchange. I doubt if any small micros are using such a system.

Make sure your purge gas is oxygen free. It is surprising how many suppliers provide only say 99.5 % free gas - not good enough.

Alternatively, you could boil the water and rechill - not as good, and expensive on energy - but it works pretty well.

I ahve heard someone dearate water with a small qualntity of fresh yeast to mop up the oxygen, but I don't think this is a good idea. hardly microbiologically sound is it ? store it for any time and you end up with growths and non yeast infection all over the place.

Hopefully someone else can provide a few more specifics of a suitable small sparge system

Cheers

[sleeper]

thanks for the advise dick. do you think you could explain the sparging procedure a little more i've never heard of or seen it done.

The simplest is to sparge a tank of water with oxygen free CO2 or nitrogen, using a sinter to ensure fine bubbles of gas

also, does anyone out there now how to do a gas push out of a vertical leaf filterer. i don't see how you could do that and still keep perlite on the filters.

thanks again guys

[Tbrew]

You are right to be concerned about using water for filter pushes. Water is typically high in O2. If doing so use an O2 meter to confirm when you have an increase. Without a meter you might be able to see the water swirls in the beer looking through a sight glass (they do not instantly blend as you might expect) and stop right away when you see this.

To make low tech DA water just fill a tank that is equipped with a sintered (carbonating) stone with cold (as possible) carbon etc. filtered water. Start bubbling CO2 through the water. If you can safely maintain top pressure it should help increase the rate of O2 removal. I have done it in the past and it took about 4 hours to get low values but this is highly dependent on the application (i.e. volume, gas flow, pressure, temperature, size of stone) so you will need to confirm your procedure.

As far as gas pushes on vertical leaf filters, it cannot be done. The cake will slide off when gas enters the bell (this is one of the advantages of this design because of very quick discharges in high volume operations). Unfortunately these filters are not forgiving to operational disruptions. This is why small brewers most commonly use horizontal leaf filters because they are much more forgiving in regards to filter stops and gas push outs etc.

[sleeper]

tbrew are you sure that you cannot do a gas push on a vertical leaf filter? i have been trying to attempt this for the last week and have had one seemingly successfull attempt. (if it wasn't for me not following my origanal proceedure i think they all would have been successfull). i kept my eye on the sight glass and took samples and i sincerly feel that a gas push can be done, but i would like to hear anyone's comments about that.

since we are a small and very cheap brewery (not to mention that i don't want to put the extra work into making DA water) i no longer think it as an option.

[oppigards]

I have a horisontal DE filter and I have tried to push out the beer from the filter bell at the end of filtering with co2. I have failed, when the beer level comes down to the first filter screen, co2 starts to go through the cake and no more beer will be pushed out of the bell. I have let the co2 in from the top of the bell.

Cheers

[Tbrew]

Pushing beer from a filter (w/ CO2 or Water) means you are still filtering the beer and thus you need to keep your DE cake whole and effective. I find it very surprising that anyone could keep a DE cake together in an effective state, on a vertical surface, while pushing with gas (we are talking vertical right?). On filters with the screens oriented horizontally no such problem.(you can do imperfect bell pushes back to an ageing tank that will be filtered in the future)

Note that many horizontal leaf filters have a "rest" element below the main elements. This rest element is the lowest screen and has a separate pipe to the filter outlet that joins the main elements pipe. On push out you close the main elements valve and only use the bottom "rest" element to do a push. Otherwise you will have the gas, yeasties and proteins coming out as soon as the first filter plate is exposed to gas. Using just the rest element gives you very little surface area and the time for push out can be quite long (be sure to continue to respect you maximum differential pressure even for this stage). Without a rest element I would forget about gas push outs and only attempt beer recovery from the filter bell if you have de-aerated water and high gravity
brewing.
Cheers.

[sleeper]

oppigards, alough we have a vertical leaf filterer i have experinced the same problems.

tbrew, thanks for your advice. and it seems that you might ultimitly be correct. that a gas push out cannot be done. i was just hanging on a thread of hope, and i still am so hang with me for a sec.

1. we use stricly perlite and no DE even though it is a DE filter. i talked to our head brewer (dale) and he remembered a post on here about perlite making a cake that held together better then a DE/perlite cake. (it is a vertical filter)

2. the pressure on the filterer is usually no more than 2bars, i put the filterer into a recircultaion, and i hook up co2 to were the unfiltered beer was going into the filterer. turn off the filter and open the circut again as i'm pushin co2 wouldn't this be just the same thing as pushing beer?

i'd like to hear what anyone thinks. thanks guys.

[malty1]

I have used a Velo vertical leaf filter and have successfully used CO2 to push most of the beer out.

I was able to attach CO2 to the top of the bell housing and push the remaining beer out. I used a small inline cartridge filter to catch any dislodged DE. It is extremely important to maintain a constant pressure throughout the process. If your filter pressure is already high, the results of this method will deteriorate quickly.

I agree that this is not the ideal way to purge a filter (DA water is better) but the cost of the cartridge filter was much less than the potential profit loss of the beer.

Cheers,
Aaron

[Tbrew]

I forgot to mention the somewhat obvious point (still worth mentioning though IMHO) that you can do a messy (even very messy) push back to an aging tank where the remains would be filtered at a latter point with the next batch. Low loss and very safe in regards to beer clarity.

[Brewdoctor]

It is most definitely possible to set beds in DA water on a vertical leaf. Precoat is standard 1/3 coarse 2/3 fine DE and a seasoned cellarman can push the water out after the cake is set with virtually no cake loss. I don't know how well this works with perlite though.