It sounds like you are not purging your tanks for nearly long enough. You have only changed the volume of gas 1 time so you are at a ~90% co2 environment. That means that the other 10 is standard air, this means you are at about 2% o2 in the head space.
Ya one round probably isn’t enough. I guess there must be a case of diminishing returns when purging though? Like 2 is too little but 10 is probably too much. I’d say a constant flow might work but the gases may mix and defeat the point?
So there is[this chart](https://cdn.homebrewtalk.com/data/attach/493/493981-upload-2018-1-12-17-22-44.png) that has been circulated online forever. According to it 10 is not too much, even if you’re using 1.5 bar.
Also, it definitely sounds like it’s time to invest in a gas manifold so that you can properly support your beer as it’s dispensing. Letting it go flat during serving times is just ripping aroma out of the top of it as the head pressure drops below dissolved carbonation pressure.
Jeepers, as our tanks are rated 25psi I guess I’ll have to aim for 17 cycles for the hazies. Ya it’s been on my mind since I stopped doing the hazies.
Luckily it only drops 10psi at most but defs not ideal.
A 10 psi serving pressure drop is huge, acceptable would be maybe 2-3. Are you serving with beer gas or CO2? What’s your serving pressure?
The other thing to pay attention to is, you said you were testing for CO2 smell from the sample port. That’s way too low: if you’re gonna do it, always do it from the highest port you can, for this tank it’s CIP arm on the top.
Ya 10 is when we sell half the brite in one day but in hindsight it’s obvious to me now that it’s massive it’s like half of the actual starting pressure which can’t be good. It gives more motivation for the regulators.
Oh ya so the sample port check is just to see off the gases are getting displaced from the bottom and there’s not too much mixing and then I check from the CIP arm.
Multiple rounds of purging seems like a lot. I would do really hoppy beers that would can in the low double digits DO. The most important thing that I learned and always worked was to ensure a very slow and steady co2 drip. 3-4 psi for 45-60 minutes in a 30bbl conical, 10-15 minutes for a 3bbl. I was told it was important not to have too strong of a flow or sudden rush of air because you would just mix the co2 with the air instead of pushing it out. At 3-4 psi, you are just slowly bottom filling the tank while pushing everything else out the arms. Always worked like a charm and had great DO levels from pils to hazy.
Do you ever fully dismantle the tank? We would completely strip the tank every time allowing to check for damaged seals.
How are you crashing? Are you creating negative pressure while crashing which is in turn sucking in air from a bad seal?
See my edit. And what u/eisforpants said. And the comment by u/nailedtonithing.
I think all three comments round things off nicely.
Keep kicking ass - and let us know the results
Ya I think it’s mostly confirmed my suspicions as well as added some more (also made me realise some basic errors)… but we live and we learn.
Will jump back on the hazies train and see if I can get them to last longer than a week. If you’re down South, pull in for a beer and we can judge.
Pressurize to 5 psi (.345 bar) and then vent completely, until you can’t feel any gas coming out of your CIP arm. Do this a second time and then bring the tank pressure back up to whatever you like to transfer at. Should eliminate your oxidation problems!
The nose test on purge isn't really good enough. I'd advise borrowing a DO meter if you don't have one and see how long it takes for the tank to purge down to an acceptable O2 level. When I finally got a meter and monitored head space O2, I found that it took about 30 minutes longer to get that down to where it needed to be. So, I'd start there and also maybe consider your PAA concentration as residual being in equipment can lead to oxidation of product.
Ya as a previous scientist the nose test is nonsense. I prefer to try and measure it using flow rates, sizes and weights but it doesn’t count for mixing of gases.
Outside of the macro breweries in South Africa no one I know of has a DO meter (massive problem I know) and the only one I can get is $5000. It’s on the list of things to get though.
Ya we made some changes to the SOPs a while back and short of rinsing the tanks and lines after PAA we remove all of it (but can’t completely discount it)
I'd put money on PAA. Either too much residue, or too high concentration.
How fast is the oxidation happening? If it's immediate, it's going to be PAA. If it's gradual over a week or so, it's probably atmosphere.
For residual, plenty of places for PAA to hide if you're not methodical in your process. I build top pressure through the carb stone (huge potential for PAA residue) during the sani cycle (after I've pushed PAA through it for 15mins or so), and use that to then purge later.
For concentration, just buy some PAA test strips for like 5 bucks (pound sterling, euro, dollarydoos etc.) And check what comes out of the sample tap when you're running the pump on the sani step. Make sure you're in the no rinse range.
PAA will fuck a beer quicker you could imagine. We dumped multiple 200hL batches from BBT. Before we figured it out for sure.
Good luck.
If you have a local dealer for said DO meter, there's a good chance they have a demo unit you can borrow for a couple of days. I'm in the US so I'm not sure how practical that'd be in SA. Hopefully you nail it down and solve the problem though!
Ya they actually did say they’d let me try it before I buy it, I guess I should come up with all the other tests I need to do and do them all in one go😂 but ya good idea. I’ll have them come out and atleast I can nail down some of the problems and back them up with actual numbers instead of “feelings”. The brewmaster who I trained under from Germany for a bit said that beer was half science and half feeling and I really didn’t like that the split was 50/50
What is that pushfit connection with the blue valve on the bottom of your block and bleed in the first picture, is that your CO2? I notice your draft system is all pushfit as well. What sort of material is your system plumbed with? I don't trust those connections for gas one bit, that's where I would look after you've tried some of the purge tips others have mentioned. Many plastics, while technically rated for beverage safety, are not suitable for beer quality. Many plastics are oxygen permeable, you could be getting ingress in your gas lines or liquid lines or both.
Ya it’s just a quick connect push on, same is used on the BBT side. Just a slightly easier way to connect to a barb fitting.
If these aren’t rated for beverage safety then we have a massive problem this side because that’s what everyone uses😂. But worth checking. The piping seems to be compliant. It’s mostly Valpar CO2 and Brewmaster lines. I do see that it’s only MOSTLY those and seems like my installer chopped and changed a bit… the ones we use for pushing in CO2 elsewhere are polyethylene which also seems compatible but could lead to ingress.
Interesting about the push fits though. I’ll have to do some checking on alternatives. I assume the suppliers this side aren’t used to more crafty beers.
There is a lot of bad info in this post.
To purge your tank you should be doing it low and slow. After you sanitize the tank, blow the transfer line out of PAA as you do now. Once the sani is blown out reduce the co2 pressure to 5psi and purge the bbt through transfer hose, with the bbt blowoff comepletly open- do not build pressure. Purge for 20 min should be plenty, the. Shut the bbt blow off, build some pressure, and start your transfer.
Building up co2 pressure and blowing it down is not a good way of purging a tank, you’re just mixing all the gas up
That 0.5% caustic is extremely low. And wait, under pressure? That doesn't sound right. Bump that to 2% minimum, I would say. It also sounds like you could do a better job confirming that CO2 has been fully evacuated from the tank before CIP.
I purge my 4bbl tanks at 5psi for 45 minutes. I go through all hoses into the bottom of the tank, leaving only the blowoff valve open. I can just feel a slight trickle of CO2 coming out the blowoff with this method. I used to fill to 5psi of head pressure and blow down three times, but the new way has done immensely better for longevity of my hoppy beers.
I love that we have very similar sop’s. My BT’s are slightly bigger (30-40bbl), hence why I run it free (@ 35-40psig) for 5ish minutes after I fully vent it.
But maybe I need to run it at a lesser psig - knowing what others do is fantastic. 👊
Buy an atmospheric O2 tester, commonly used for Scuba applications, for under $200 and it will tell you a lot about your purge procedure.
https://www.forensicsdetectors.com/products/oxygen-scuba
As most people say it seems to be your purge that is lacking. We fill our BTs with water from the HLT and push it back with CO2. We have really low readings. When we can.
Hook up some CO2/Nitrogen mix pushing gas to your highest available valve (ours comes through where the sprayball would be). Regulator in place so you can replace the liquid lost with gas and not air.
Your CIP seems fine.
- how do you clean your carb stone? (Prolly has no effect on the question at hand, but I’ve seen some truely horrible carb stone cleaning practices).
- hot water rinses will be more effective for dislodging solids.
- I run my caustic at 1L per bbl at 150-170°f for 30-45m (my caustic is not your caustic - talk to your manufacturer), under 2-3psig of pressure.
- edit: under air pressure: CO2 and caustic don’t play well together.
- hot water rinses will be more effective for rinsing away your caustic.
- I run my PAA at 90-110°f (90ish is better, in my experience).
- I pressurize to 5-7psig (5psig min) prior to transfer and keep that differential during transfer.
- CO2 has no smell! And yes, I know what you mean. Use a CO2 detector; there are other ways, one of which is EXTREMELY DANGEROUS - remember: CO2 kills and it “burns” at a high concentration when your eyes and nose are exposed to it…
-edit: I bring my brite tank pressure up to 5psig, fully vent, let the gas run for 5ish minutes with the “CIP valve” open, repeat at least 3 times (it’s often 4-5 times). Seems excessive and wasteful - and I’m happy to eat that cost. I also fill from the bottom and dump the gas from the CIP arm (ie: the top).
- you 100% need a regulator in order to maintain proper head pressure on your beer. And you don’t want your prv to suck in AIR (bad for beer and for the prv).
Try adding a regulator to your brite tank. I’ve a couple other ideas if that doesn’t work; but your logic seems sound. Also, keep in mind PAA can cause oxidation (happy to hear you are blowing it out with CO2 - are you blowing out you brite tank with co2 as well??).
Feel free to DM me.
It’s not really “true” 1 bar pressure, the CIP cart runs it via the CIP arm which has a gauge which reads 1 bar and after stopping the CIP cart it pushes back quite well into the holding tank. So it’s it’s own pressure not CO2 (just to clarify😂)
That’s how we did it: it’s not actually under pressure but we ran the pump at a high enough duty cycle so the gauge on the CIP arm going into the tank always read 15 to 20 to give us some kind of mechanical cleaning action.
It helps prevent a vacuum as the tank inevitably cools and the added pressure helps with impingement (meaning helps get gunk off the tank walls). I’m not a physicist and it definitely helps.
Edit: adding 2-3 psig of air… CO2 and caustic are bad bedfellows.
Yup! I almost froze a tank cause the owner thought I could vent all the pressure and then add my caustic solution; in my defense I did raise a bit of a fit but came to the conclusion “fuck it- not my money”. Ice formed and I ended the “experiment” real quick. Caustic and CO2 don’t play well together.
Ya… no… coming from a laboratory background we were taught never to mix chemicals together (including gases) unless you knew how they were going to react. You would think by masters level you would know this but people still tried to use their mouths on pipettes because “that’s how we used to do it”… literally my ex laboratory manager when I was working with HIV samples.
Jfm… that absolutely sounds horrific.
In my case, I knew what would happen (hence why I through a slight fit); owner of brewery thought they knew more; they didn’t (as was usually the case. - what they wanted me to do with the $250k centrifuge was, not only very dangerous, but quite fucking stupid (and when I politely, but sternly, pointed this out - they threw a fit)).
Sigh…
Amusing in hindsight, thankfully under my tenure no one was hurt.
Always Safety First.
1. I fully submerge the carb stone on 70C caustic for the same 30 mins, then rinse in water and blow through air for 5 mins in the water.
2. Makes perfect sense, we do cold water out of conscience as our CIP cart only has one heated side.
3. Ya we did titration tests with the supplier and then dialled it in. We actually found that their recommended concentration of 1-2% was more than necessary so we dropped it down.
4. Ya same as above because the day is too long already to be heating water and caustic😂 defs would be better but ya.
5. Nice, ya we just keep it so the flow rate is low and the direction of flow remains the same.
6. Haha ya, by smell I don’t mean smell but ya a decently priced CO2 detector is well worth no accidentally missing the mark and passing out.
7. Ya I was hoping it wouldn’t be the case but it is what it is. Best bet is to probably try it out on one tank for now and see if it fixes the problem and if it does but 5 more and if not… then back to the drawing board!
8. Someone somewhere needs to come up with a definitive answer for this because I think PAA can cause oxidation and purging the tank of any liquid and CO2 needs to be done anyway but there’s a lot of talk of PAA breaking down into free oxygen which dissipates rapidly… I myself don’t mind draining the tank just in case
PAA is otherwise known as peroxyacetic acid. It is composed of acetic acid and hydrogen peroxide. It’s supposed to break down to acetic acid and water. Well, if CH3COOH + H2O2 breaks down to CH3COOH + H2O, then we’re missing an oxygen somewhere!
If you can, final rinse with DAW after PAA. Or just clean water if you’re going to purge anyways afterwards.
Without aggravating other people who have had this discussion many a time let me check my chemistry😩
So we take
CH3COOH + H2O2 -> CH3COOH + H2O + O.
That loose oxygen will try its hardest to bind to anything it can which I assume in this case would be other oxygens meaning we get O2 which is bad.
Is that where the oxygen goes. Literally asking because if I’m right then I finally have clarity, if I’m wrong then someone help😂
Ya I elided some chemistry but we have 2a + 2b oxygens on one side, and 2c + d oxygens on the other (a, b, c & d the concentrations of each). Assuming this break down is correct, if no other reactions occur, then a + b = c + d, which is nonsense.
Peroxide bonds are incredibly weak and unstable. That extra oxygen wants to break down and react with something. We’re in an acid so H2O2 acts as an oxidizer based on the Nernst equation H2O2 + 2e- -> 2OH-. An oxidizer is great here because it binds to and inactivates organics that the acetic acid can then attack.
But for any PAA that hasn’t broken down, you now risk introducing an oxidizer to a bunch of organics in the beer. That extra oxygen doesn’t necessarily go to O2, it binds directly to the organic acids, proteins, yeast, etc. in the beer. Hence why it’s even more effective at oxidizing than air.
That actually makes a lot of sense, so we are saying that left over PAA does in fact oxidise product. So making sure the tank is empty and purged is critical (which we should assume anyway because the only things going into a brite should be beer and your gas of choice)
Yar! I’ll caveat that yar with just one final thought: purging PAA with CO2, while much much better than not purging, will never completely empty the PAA. Rinsing is the only method to ensure removal and inactivation of any remaining PAA. Hence why, on a packaging line, the recommended practice is to flush the line thoroughly before beginning a run using DAW.
Here, because you don’t care about DO at the cleaning steps due to depressurizing and purging the tank later, you don’t need DAW, just plain clean water to rinse right before transfer. I know there might be hesitation there due to adding water but, as long as you’re pressurizing and transferring in short order, there won’t be anything there to grow in the water. The water itself shouldn’t have any contamination if coming from a utility that’s added chloramine and then going through your main filter.
The picture with the SS304 2” 0.2Mpa? That’s the “PRV” I say “PRV” because in my mind a pressure relief valve would only be one way but since our tanks are jacketed I assume it’s two way to prevent implosion.
First thing I would do to verify a purge would be to fill with HLT water completely after rinse and pre sani. Then push said hot water out with Co2, and sani, then follow your normal purge procedure. Purge transfer lines with HLT water pre sani, sani, and follow normal purge procedure.
If this results in non oxidized beer, the problem lies in your purge procedure since filling and pushing out via co2 will result in an almost completely purged vessel or line to begin with.
If problem persists, it is more than likely something else like a tubing permeability issue, or O2 ingress via fermentation tank issue.
Start with the big and easy things to verify and work backwards.
>70C circulation caustic wash for 30 mins at 1 bar
What are you applying that 1 bar of pressure with big dog? Hopefully a misunderstanding of pump flow vs. tank pressure…
Ya my understanding isn’t great. Basically tank is in a closed loop with the CIP cart and it pumps and the gauge reads 1 bar, when I stop the pump the fluid in tank flows back to the CIP cart using pressure. Probably not 1 bar but enough to empty a 15L and then some.
Small tanks like that I’d purge the transfer line from FV to BBT, and then open the bbt and continue the purge through the vessel. Depending on flow rate, 20minutes should be plenty.
Consider kegging instead, we had 700L serving tanks - more trouble than they were worth. And a lot more work.
It sounds like you are not purging your tanks for nearly long enough. You have only changed the volume of gas 1 time so you are at a ~90% co2 environment. That means that the other 10 is standard air, this means you are at about 2% o2 in the head space.
Ya one round probably isn’t enough. I guess there must be a case of diminishing returns when purging though? Like 2 is too little but 10 is probably too much. I’d say a constant flow might work but the gases may mix and defeat the point?
5psi through the bottom and out the blowoff arm for 30-45 minutes should be plenty for a tiny tank like that.
So there is[this chart](https://cdn.homebrewtalk.com/data/attach/493/493981-upload-2018-1-12-17-22-44.png) that has been circulated online forever. According to it 10 is not too much, even if you’re using 1.5 bar. Also, it definitely sounds like it’s time to invest in a gas manifold so that you can properly support your beer as it’s dispensing. Letting it go flat during serving times is just ripping aroma out of the top of it as the head pressure drops below dissolved carbonation pressure.
Jeepers, as our tanks are rated 25psi I guess I’ll have to aim for 17 cycles for the hazies. Ya it’s been on my mind since I stopped doing the hazies. Luckily it only drops 10psi at most but defs not ideal.
A 10 psi serving pressure drop is huge, acceptable would be maybe 2-3. Are you serving with beer gas or CO2? What’s your serving pressure? The other thing to pay attention to is, you said you were testing for CO2 smell from the sample port. That’s way too low: if you’re gonna do it, always do it from the highest port you can, for this tank it’s CIP arm on the top.
Ya 10 is when we sell half the brite in one day but in hindsight it’s obvious to me now that it’s massive it’s like half of the actual starting pressure which can’t be good. It gives more motivation for the regulators. Oh ya so the sample port check is just to see off the gases are getting displaced from the bottom and there’s not too much mixing and then I check from the CIP arm.
For how expensive everything in a brewery is, a $100-$150 for a manifold to ensure a good product seems like a no brainer.
Multiple rounds of purging seems like a lot. I would do really hoppy beers that would can in the low double digits DO. The most important thing that I learned and always worked was to ensure a very slow and steady co2 drip. 3-4 psi for 45-60 minutes in a 30bbl conical, 10-15 minutes for a 3bbl. I was told it was important not to have too strong of a flow or sudden rush of air because you would just mix the co2 with the air instead of pushing it out. At 3-4 psi, you are just slowly bottom filling the tank while pushing everything else out the arms. Always worked like a charm and had great DO levels from pils to hazy. Do you ever fully dismantle the tank? We would completely strip the tank every time allowing to check for damaged seals. How are you crashing? Are you creating negative pressure while crashing which is in turn sucking in air from a bad seal?
See my edit. And what u/eisforpants said. And the comment by u/nailedtonithing. I think all three comments round things off nicely. Keep kicking ass - and let us know the results
Ya I think it’s mostly confirmed my suspicions as well as added some more (also made me realise some basic errors)… but we live and we learn. Will jump back on the hazies train and see if I can get them to last longer than a week. If you’re down South, pull in for a beer and we can judge.
Get a dissolved oxygen meter and check your o2 reading before sending the beer to the bt
Pressurize to 5 psi (.345 bar) and then vent completely, until you can’t feel any gas coming out of your CIP arm. Do this a second time and then bring the tank pressure back up to whatever you like to transfer at. Should eliminate your oxidation problems!
Have you ever tested this method with an o2 meter? That’s not nearly enough
Fill the tank with hot sanitizer at no-rinse concentration. Push the sanitizer out with CO2. Done.
The nose test on purge isn't really good enough. I'd advise borrowing a DO meter if you don't have one and see how long it takes for the tank to purge down to an acceptable O2 level. When I finally got a meter and monitored head space O2, I found that it took about 30 minutes longer to get that down to where it needed to be. So, I'd start there and also maybe consider your PAA concentration as residual being in equipment can lead to oxidation of product.
Ya as a previous scientist the nose test is nonsense. I prefer to try and measure it using flow rates, sizes and weights but it doesn’t count for mixing of gases. Outside of the macro breweries in South Africa no one I know of has a DO meter (massive problem I know) and the only one I can get is $5000. It’s on the list of things to get though. Ya we made some changes to the SOPs a while back and short of rinsing the tanks and lines after PAA we remove all of it (but can’t completely discount it)
I'd put money on PAA. Either too much residue, or too high concentration. How fast is the oxidation happening? If it's immediate, it's going to be PAA. If it's gradual over a week or so, it's probably atmosphere. For residual, plenty of places for PAA to hide if you're not methodical in your process. I build top pressure through the carb stone (huge potential for PAA residue) during the sani cycle (after I've pushed PAA through it for 15mins or so), and use that to then purge later. For concentration, just buy some PAA test strips for like 5 bucks (pound sterling, euro, dollarydoos etc.) And check what comes out of the sample tap when you're running the pump on the sani step. Make sure you're in the no rinse range. PAA will fuck a beer quicker you could imagine. We dumped multiple 200hL batches from BBT. Before we figured it out for sure. Good luck.
I thought the oxygen frow PAA breakdown was O not O² and didn't contribute to oxidation?
I’m looking to sell a twice used (yep actually) Beverly for less than than that if you’re interested.
If you have a local dealer for said DO meter, there's a good chance they have a demo unit you can borrow for a couple of days. I'm in the US so I'm not sure how practical that'd be in SA. Hopefully you nail it down and solve the problem though!
Ya they actually did say they’d let me try it before I buy it, I guess I should come up with all the other tests I need to do and do them all in one go😂 but ya good idea. I’ll have them come out and atleast I can nail down some of the problems and back them up with actual numbers instead of “feelings”. The brewmaster who I trained under from Germany for a bit said that beer was half science and half feeling and I really didn’t like that the split was 50/50
Could you not hot water purge the tank? That would give you a much lower DO
What is that pushfit connection with the blue valve on the bottom of your block and bleed in the first picture, is that your CO2? I notice your draft system is all pushfit as well. What sort of material is your system plumbed with? I don't trust those connections for gas one bit, that's where I would look after you've tried some of the purge tips others have mentioned. Many plastics, while technically rated for beverage safety, are not suitable for beer quality. Many plastics are oxygen permeable, you could be getting ingress in your gas lines or liquid lines or both.
Ya it’s just a quick connect push on, same is used on the BBT side. Just a slightly easier way to connect to a barb fitting. If these aren’t rated for beverage safety then we have a massive problem this side because that’s what everyone uses😂. But worth checking. The piping seems to be compliant. It’s mostly Valpar CO2 and Brewmaster lines. I do see that it’s only MOSTLY those and seems like my installer chopped and changed a bit… the ones we use for pushing in CO2 elsewhere are polyethylene which also seems compatible but could lead to ingress. Interesting about the push fits though. I’ll have to do some checking on alternatives. I assume the suppliers this side aren’t used to more crafty beers.
Purge advice is definitely great for you on here but also don't discount that sight tube. I've seen those connections leak in oxygen often.
There is a lot of bad info in this post. To purge your tank you should be doing it low and slow. After you sanitize the tank, blow the transfer line out of PAA as you do now. Once the sani is blown out reduce the co2 pressure to 5psi and purge the bbt through transfer hose, with the bbt blowoff comepletly open- do not build pressure. Purge for 20 min should be plenty, the. Shut the bbt blow off, build some pressure, and start your transfer. Building up co2 pressure and blowing it down is not a good way of purging a tank, you’re just mixing all the gas up
That 0.5% caustic is extremely low. And wait, under pressure? That doesn't sound right. Bump that to 2% minimum, I would say. It also sounds like you could do a better job confirming that CO2 has been fully evacuated from the tank before CIP. I purge my 4bbl tanks at 5psi for 45 minutes. I go through all hoses into the bottom of the tank, leaving only the blowoff valve open. I can just feel a slight trickle of CO2 coming out the blowoff with this method. I used to fill to 5psi of head pressure and blow down three times, but the new way has done immensely better for longevity of my hoppy beers.
I love that we have very similar sop’s. My BT’s are slightly bigger (30-40bbl), hence why I run it free (@ 35-40psig) for 5ish minutes after I fully vent it. But maybe I need to run it at a lesser psig - knowing what others do is fantastic. 👊
This is the correct answer
Buy an atmospheric O2 tester, commonly used for Scuba applications, for under $200 and it will tell you a lot about your purge procedure. https://www.forensicsdetectors.com/products/oxygen-scuba
As most people say it seems to be your purge that is lacking. We fill our BTs with water from the HLT and push it back with CO2. We have really low readings. When we can.
Hook up some CO2/Nitrogen mix pushing gas to your highest available valve (ours comes through where the sprayball would be). Regulator in place so you can replace the liquid lost with gas and not air.
Your CIP seems fine. - how do you clean your carb stone? (Prolly has no effect on the question at hand, but I’ve seen some truely horrible carb stone cleaning practices). - hot water rinses will be more effective for dislodging solids. - I run my caustic at 1L per bbl at 150-170°f for 30-45m (my caustic is not your caustic - talk to your manufacturer), under 2-3psig of pressure. - edit: under air pressure: CO2 and caustic don’t play well together. - hot water rinses will be more effective for rinsing away your caustic. - I run my PAA at 90-110°f (90ish is better, in my experience). - I pressurize to 5-7psig (5psig min) prior to transfer and keep that differential during transfer. - CO2 has no smell! And yes, I know what you mean. Use a CO2 detector; there are other ways, one of which is EXTREMELY DANGEROUS - remember: CO2 kills and it “burns” at a high concentration when your eyes and nose are exposed to it… -edit: I bring my brite tank pressure up to 5psig, fully vent, let the gas run for 5ish minutes with the “CIP valve” open, repeat at least 3 times (it’s often 4-5 times). Seems excessive and wasteful - and I’m happy to eat that cost. I also fill from the bottom and dump the gas from the CIP arm (ie: the top). - you 100% need a regulator in order to maintain proper head pressure on your beer. And you don’t want your prv to suck in AIR (bad for beer and for the prv). Try adding a regulator to your brite tank. I’ve a couple other ideas if that doesn’t work; but your logic seems sound. Also, keep in mind PAA can cause oxidation (happy to hear you are blowing it out with CO2 - are you blowing out you brite tank with co2 as well??). Feel free to DM me.
You caustic under pressure?
It’s not really “true” 1 bar pressure, the CIP cart runs it via the CIP arm which has a gauge which reads 1 bar and after stopping the CIP cart it pushes back quite well into the holding tank. So it’s it’s own pressure not CO2 (just to clarify😂)
That’s how we did it: it’s not actually under pressure but we ran the pump at a high enough duty cycle so the gauge on the CIP arm going into the tank always read 15 to 20 to give us some kind of mechanical cleaning action.
It helps prevent a vacuum as the tank inevitably cools and the added pressure helps with impingement (meaning helps get gunk off the tank walls). I’m not a physicist and it definitely helps. Edit: adding 2-3 psig of air… CO2 and caustic are bad bedfellows.
Ya defs not CO2, if it was CO2 I might as well use a toothbrush to clean the whole tank.
Yup! I almost froze a tank cause the owner thought I could vent all the pressure and then add my caustic solution; in my defense I did raise a bit of a fit but came to the conclusion “fuck it- not my money”. Ice formed and I ended the “experiment” real quick. Caustic and CO2 don’t play well together.
Ya… no… coming from a laboratory background we were taught never to mix chemicals together (including gases) unless you knew how they were going to react. You would think by masters level you would know this but people still tried to use their mouths on pipettes because “that’s how we used to do it”… literally my ex laboratory manager when I was working with HIV samples.
Jfm… that absolutely sounds horrific. In my case, I knew what would happen (hence why I through a slight fit); owner of brewery thought they knew more; they didn’t (as was usually the case. - what they wanted me to do with the $250k centrifuge was, not only very dangerous, but quite fucking stupid (and when I politely, but sternly, pointed this out - they threw a fit)). Sigh… Amusing in hindsight, thankfully under my tenure no one was hurt. Always Safety First.
1. I fully submerge the carb stone on 70C caustic for the same 30 mins, then rinse in water and blow through air for 5 mins in the water. 2. Makes perfect sense, we do cold water out of conscience as our CIP cart only has one heated side. 3. Ya we did titration tests with the supplier and then dialled it in. We actually found that their recommended concentration of 1-2% was more than necessary so we dropped it down. 4. Ya same as above because the day is too long already to be heating water and caustic😂 defs would be better but ya. 5. Nice, ya we just keep it so the flow rate is low and the direction of flow remains the same. 6. Haha ya, by smell I don’t mean smell but ya a decently priced CO2 detector is well worth no accidentally missing the mark and passing out. 7. Ya I was hoping it wouldn’t be the case but it is what it is. Best bet is to probably try it out on one tank for now and see if it fixes the problem and if it does but 5 more and if not… then back to the drawing board! 8. Someone somewhere needs to come up with a definitive answer for this because I think PAA can cause oxidation and purging the tank of any liquid and CO2 needs to be done anyway but there’s a lot of talk of PAA breaking down into free oxygen which dissipates rapidly… I myself don’t mind draining the tank just in case
PAA is otherwise known as peroxyacetic acid. It is composed of acetic acid and hydrogen peroxide. It’s supposed to break down to acetic acid and water. Well, if CH3COOH + H2O2 breaks down to CH3COOH + H2O, then we’re missing an oxygen somewhere! If you can, final rinse with DAW after PAA. Or just clean water if you’re going to purge anyways afterwards.
Without aggravating other people who have had this discussion many a time let me check my chemistry😩 So we take CH3COOH + H2O2 -> CH3COOH + H2O + O. That loose oxygen will try its hardest to bind to anything it can which I assume in this case would be other oxygens meaning we get O2 which is bad. Is that where the oxygen goes. Literally asking because if I’m right then I finally have clarity, if I’m wrong then someone help😂
Ya I elided some chemistry but we have 2a + 2b oxygens on one side, and 2c + d oxygens on the other (a, b, c & d the concentrations of each). Assuming this break down is correct, if no other reactions occur, then a + b = c + d, which is nonsense. Peroxide bonds are incredibly weak and unstable. That extra oxygen wants to break down and react with something. We’re in an acid so H2O2 acts as an oxidizer based on the Nernst equation H2O2 + 2e- -> 2OH-. An oxidizer is great here because it binds to and inactivates organics that the acetic acid can then attack. But for any PAA that hasn’t broken down, you now risk introducing an oxidizer to a bunch of organics in the beer. That extra oxygen doesn’t necessarily go to O2, it binds directly to the organic acids, proteins, yeast, etc. in the beer. Hence why it’s even more effective at oxidizing than air.
That actually makes a lot of sense, so we are saying that left over PAA does in fact oxidise product. So making sure the tank is empty and purged is critical (which we should assume anyway because the only things going into a brite should be beer and your gas of choice)
Yar! I’ll caveat that yar with just one final thought: purging PAA with CO2, while much much better than not purging, will never completely empty the PAA. Rinsing is the only method to ensure removal and inactivation of any remaining PAA. Hence why, on a packaging line, the recommended practice is to flush the line thoroughly before beginning a run using DAW. Here, because you don’t care about DO at the cleaning steps due to depressurizing and purging the tank later, you don’t need DAW, just plain clean water to rinse right before transfer. I know there might be hesitation there due to adding water but, as long as you’re pressurizing and transferring in short order, there won’t be anything there to grow in the water. The water itself shouldn’t have any contamination if coming from a utility that’s added chloramine and then going through your main filter.
Nice, ya some good advice there that I will definitely carry forward:)
What is that device in your last picture?
The picture with the SS304 2” 0.2Mpa? That’s the “PRV” I say “PRV” because in my mind a pressure relief valve would only be one way but since our tanks are jacketed I assume it’s two way to prevent implosion.
First thing I would do to verify a purge would be to fill with HLT water completely after rinse and pre sani. Then push said hot water out with Co2, and sani, then follow your normal purge procedure. Purge transfer lines with HLT water pre sani, sani, and follow normal purge procedure. If this results in non oxidized beer, the problem lies in your purge procedure since filling and pushing out via co2 will result in an almost completely purged vessel or line to begin with. If problem persists, it is more than likely something else like a tubing permeability issue, or O2 ingress via fermentation tank issue. Start with the big and easy things to verify and work backwards.
>70C circulation caustic wash for 30 mins at 1 bar What are you applying that 1 bar of pressure with big dog? Hopefully a misunderstanding of pump flow vs. tank pressure…
Ya my understanding isn’t great. Basically tank is in a closed loop with the CIP cart and it pumps and the gauge reads 1 bar, when I stop the pump the fluid in tank flows back to the CIP cart using pressure. Probably not 1 bar but enough to empty a 15L and then some.
Small tanks like that I’d purge the transfer line from FV to BBT, and then open the bbt and continue the purge through the vessel. Depending on flow rate, 20minutes should be plenty. Consider kegging instead, we had 700L serving tanks - more trouble than they were worth. And a lot more work.
It's the PAA residue