Best method for tank purging?

[emergent7]

I am looking to modify our tank purging procedure and wanted to see if there were any accepted best methods that we could talk about. Currently, we are first pressurizing our sanitized tanks and then allowing them to vent for about an hour under pressure.

I measured the drop in oxygen content of the discharge every 5 minutes and it took about 2 hours to get it down to 2% oxygen. I don't have the data to compare to a pressurized tank. I had previously thought that there would be more "layering" due to heavy CO2 in an unpressurized tank but just read a thread here that debunked that.

Anyways, any ideas? We are using mostly 800 bbl-ish horizontal tanks.

[brewmaster 2011]

Are you pushing co2 in from the bottom? and what is the pressure of the co2 going in?

[emergent7]

Yes, we are pushing in from the bottom. Cellarman reports that they're going in at about 25 psi, which seems like a lot to me.

[brewmaster 2011]

the lower the better cause it is a lager tank. Try 5psi it will take alot longer but i think it will help alot.

[emergent7]

Yes, makes sense. I'm trying to find the best balance between thoroughness and time efficiency because sometimes these tanks are being turned over very quickly and need to be purged immediately.

[TL Services]

If you have deaerated water, fill the tank with that then push out with either CO2 or nitrogen.

Water doesn't have to go to drain & wasted, but can be run to another tank to use for flush water, eg. pre-cleaning, etc.

Would also use a lot less CO2, thus saving both money and gaining you "environmentally friendly" points

[emergent7]

>If you have deaerated water, fill the tank with that then push out with either CO2 or nitrogen.


We would love to do this but it would become a logistics nightmare trying to juggle that water around, good idea though. I'm still quite interested if there is a difference between pressurizing the tank first or not. I am thinking the solution may be to try to get as much complete purging done well before the tank is ready to be filled instead of rushing it right beforehand.

[TL Services]

I don't see that pressurising the tank first is going to make a great difference to time, CO2 usage or final O2 level. As above, bleeding CO2 in slowly is more likely to give a quiet fill than blasting it in.

But I have a question for you: I'm assuming that after cleaning your tanks are full of air, hence the need to reduce oxygen level. At what point in your current regime is the air introduced? And would it be possible to substitute nitrogen at that point?

That way you eliminate the oxygen and N2 doesn't have the same associated problems when caustic cleaning as does CO2.

[jfulton]

I remember reading a paper from a Weihenstephan study where they determined that the most efficient & timely way to do any tank is to pressurize it to 5 psi, purge through airlock, pressurize again to 5 psi, purge again, then pressurize to your receiving pressure. This led to the lowest O2 levels vs. time and gas used.

Cheers,

[nohandslance]

Distribution Timeline

What kind of times are we looking at from BBT, Filler, Distribution, Retailer to consumer.
If you have sound brewing practices and a quick turnaround on your beers, I do not see a need for excessive CO2 purge. How about a small amount of 'live yeast' for some O2 scavenging.
You are at 800bbls in your tanks, so you must be producing quite a bit so look at your turn around time and make adjustments.

Lance

[Ted Briggs]

"pressurize it to 5 psi, purge through airlock, pressurize again to 5 psi, purge again, then pressurize to your receiving pressure"

Read the same paper Jamie and have been doing it ever since. Best method to control a mixed gas environment and ignore the myth of a 'co2 blanket'. This method is consistant and repeatable and the data showed good results while a 3rd purge resulted in diminishing returns. As far as speed goes- run the gas in as fast as your dewers will feed, But for safety id keep the regulator below 30psi.
On another hand, many brewers are seeing good results cleaning under preassure with acid and only venting and opening a tank every 3-5th use. Were talking BBT's and not fermentors. You could look into this to save time and $$.

[Geoff Logan]

This is interesting. We pressurize to 14 psi, vent, pressurize to 14 psi again, vent, then up again to 5 psi to receive. It takes a while and uses quite a bit of CO2 but since I don't have an effective device to measure O2 in our tanks I figure this is a good way to go.

[DBrewer]

I remember reading a paper from a Weihenstephan study where they determined that the most efficient & timely way to do any tank is to pressurize it to 5 psi, purge through airlock, pressurize again to 5 psi, purge again, then pressurize to your receiving pressure. This led to the lowest O2 levels vs. time and gas used.

Cheers,

If you happen to have a link to that paper could you either post it or send me a PM. I tried to find it but didin't come up with anything...

[Beer_Nut]

If you happen to have a link to that paper could you either post it or send me a PM. I tried to find it but didin't come up with anything...

I would actually like to read that as well.

[Ted Briggs]

I tride to re-find it once myself but couldent. its at least 10 years,if not 15years old though.