Getting the air out
What are those of you with bigger tanks doing to reduce air pickup throughout your filtration and bottling process? I've run our O2 meter at multiple ppoints throughout the process and it seems we can't fully purge our tanks. We purged a tank with CO2 for 45 minutes this morning, then immediately upon running into it our airs jumped up 0.4. This was in a 390-bbl cylindrical ruh tank.
Short of filling the tank with DA water and pushing it out with CO2 (a very costly and time consuming prospect at this volume, not to mention the tank management nightmare), anyone have any tips or tricks?
Darel: If you can find them, check out the DO readings on the tanks when I ran the filters a few years ago.
There's no one easy answer, rather it's the attention to many small details. Which, I fully understand, can be difficult in your work environment.
It can be done, however, without a major change in the operations. Cooperation among and 100% compliance from your employees is key.
Sorry if my input is at all disruptive, but feel free to contact me if you wish.
I don't know the details of your plant, but the following may be useful thoughts. Some may appear to be 'stating the obvious', but as I often say: "Better to hear it twice than not hear it once!"...
- Are you purging pipework/mains/filter before running into the tanks? Packing with DA water, then running that to drain (as near to the tank as possible) and pushing it out with beer when you go forward on your filter;
- Are you maintaining top-pressure when filling? Make sure you don't have any air leaks when you're bleeding-off as the tank starts to fill;
- CO2 is heavier than air, so make sure you're purging upwards and venting air at the highest point;
- What is the DO2 of the beer as it comes off your filter? Is this good or higher than pre-filter? That may help to give you a pointer;
- Check any valves, joints, etc. between filter and tank. Often air can leak in without any sign of beer leakage out. Especially look for flow restrictions, where low pressure can suck air in through a weak seal;
As pennbrew2 said, it is all about attention to detail - taking a few minutes to 'walk the line' might just throw up some possibles.
Thanks Guys (pun intended)!
Here's an example of what we came up with following beer Friday morning through primary filtration (these are 1950s vertical-leaf DE filters BTW, yes with an open slurry but oddly CO2 outgassing seems to minimize or eliminate air pickup, though we are working on that):
Ruh tank: .2
Cooler outlet: .2
Filter outlet: .2
Primary "Y", with CO2 both off and on(which probably really only means anything to Guy): .2
As soon as beer hit the zwickel in the tank: .9
Full tank: .6
This was after purging the tank with CO2 for 45 minutes.
I feel pretty comfortable we've nailed the source of the O2. Our filtermen are trained to inspect all joints, gaskets, pumps, and any other possible point of air intrusion, and given how often the told me they had to tighten a triclamp or swap a gasket, I'm comfortable they're actually doing it.
We do purge and push with DA water on every tank.
I suppose, as mentioned, there's no real easy answer other than the difficult one. Thanks a lot!
Three things - before you embark on the 'difficult':
- Check your CO2 supply;
- Make sure you're not pulling any air into your meter through the zwickel that is giving you a false 'high O2';
- Check the tanks after CO2 purge but before running beer into them.
First one will given you complete reassurance your CO2 is good;
Second (and I admit, Zwickels are not common over here so I apologise for any lack of in-depth knowledge of them) is to make sure you're not seeing erroneous results;
Third will give you a comparison between the incoming CO2 (above) and the tank, to measure the effectiveness of your purge.
Excellent idea - checking incoming CO2 and the zwickels.
Tanks after purge but pre-beer were in the 4000 ppb range - still very high.
4000ppb? That's 4ppm which - roughly - is about 50% of what a meter will read in air...
Originally Posted by Darel Matthews
Would I be right in understanding - as you say tanks - that you have checked more than one and they're all similar levels? If so I'd suggest it is either your CO2 that's carrying air/O2 with it or your purge is not allowing the incoming CO2 to layer from the bottom of the tank, thus forcing the air out of the top.
- Do you have the CO2 purge connection at the bottom of the tanks?
- What pressure/inlet dia. do you have for it?
- Are you venting from the top of the tank?
Darel, you have a PM
Last edited by KWLSD; 10-27-2009 at 12:50 AM.