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[Solved]: Silcone air-lock not working.

Post #1 made 7 years ago
by PistolPatch
[EDIT: Now solved. See this post below. A good example though of how hard some answers are to find.]

Just when I thought I had seen everything!

Okay, here's a pic of my (and youmustbemellow's) last brew...
Copy of Fermenter.jpg
It's a simple pail with two holes in the lid. The centre one was originally blanked off before I posted this but, in this pic, has a Steri-lock now attached. The hole that is off-centre has a five-holed bung that I can do all sorts of stuff with. A five-holed bung comes in two parts. Here's some pics showing the two parts and when it is assembled...
Copy of Five-Holed Bung - Separtated.jpg
Copy of Five-Holed Bung - Assembled.jpg
One of many advantages of such a bung is that it also acts as an air-lock. As pressure in the fermenter increases, obviously, the "flap" between the two parts separates and allows CO2 to escape.

I've used these five-holed bungs on countless brews, love them, so figure this one out...

Pitched on Monday night. On Wednesday morning, I happened to notice that the fermenter lid was bulging upwards (should have taken a pic) at least an inch (2.5cms but I think about 3.5) above the top of the fermenter.

I've used silicone bungs in some wild transferring experiments to know that your lid will usually blow out way before they do but, what was happening here? This is simple, basic physics, the pressure should easily escape?

Anyway, I peeled the flap out to let the pressure off but had to repeat that several more times on Wednesday. I would have swapped the bung over but didn't have another one up my sleeve at that time.

This morning (Thursday), I released the pressure again and sprayed some no-rinse sanitiser between the two parts thinking that maybe I or youmustbemellow might have assembled it dry or something??? (That shouldn't matter anyway).

Came back three hours later and lid swelling again :shock:. It gets worse though...

A few hours ago, I finally had a replacement bung available so I swapped out the bungs. Just before writing this, lid was swelling again, bung wasn't opening. What the...???

Have now put a normal air-lock into the centre bung.

This is honestly the weirdest thing I have ever seen in brewing. The only thing I just thought of was that maybe I had the silicone bungs in some chemical that made them sticky but I know that is not correct.

So, figure that one out!
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Last edited by PistolPatch on 19 Jun 2017, 00:06, edited 3 times in total.
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Post #2 made 7 years ago
by PistolPatch
Forgot to mention that I was so asounded by this that I actually blew through the original bung after I replaced it and there were no problems with the flap opening.

Strangest experience I have ever had in brewing to date.
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Post #4 made 7 years ago
by Rick
This is something I've been unable to explain myself, and intermittently encounter the same thing with blow off tubes. The lid has blown off before it would bubble out of the starsan jug. I always make sure the fermenter tube is away from the beer, and even make sure the hose isn't kinked ... even tried as far as reducing the amount of starsan in the jug. Sometimes it just wants to blow the lid off before following the obvious path of least resistance.

Hopefully one day I get my epiphany, but for now I'm also similarly stumped.
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Post #5 made 7 years ago
by ShorePoints
Is it possible that the disc is a one-way valve? That would mean that in previous uses you always had it the right way. When you blew through it, you also guessed the right way. If it does not open in the reverse direction it would explain the air-tight occasion.
If the disc is a part of the truncated cone and not reversible, then the only thing I can think of is that a diaphragm inside got inverted.
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Post #6 made 7 years ago
by goulaigan
Oddly enough, like Rick I have also experienced this with blowoff tubes. No idea why either. This is while the blowoff is bubbling away in the jar of starsan, if i push the lid down the bubbling stops for a while then starts back up as the lid starts to bulge again... Never had a lid come off yet thankfully but definitely bulge at least a couple cm... And the tube I use is larger than any of my airlocks...
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Post #7 made 7 years ago
by ShorePoints
OK, if this is not a hoax of some kind, the only ways to build up back-pressure in the fermenter entail very restricted outflow of gases. Blockage or extreme tube restriction, tube exit point sufficiently deep in aqueous solution and/or extreme density of liquid at the exit point of the blow-off tube come to mind. Wildly different barometric pressures could not do it alone.
Is this for real?
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Post #8 made 7 years ago
by PistolPatch
ShorePoints wrote:OK, if this is not a hoax of some kind...
That's exactly what I would be thinking reading this so I'm really glad to see that Rick and goul had the same sort of inexplicable thing.

The bung only goes together one-way, it's an extremely simple system. I have six of them and they have never done this before. To have two of them do it on the same batch is extra crazy.

Once this batch is fermented, I'll see if I can muck around with this fermenter and bungs a bit (eg try pumping some CO2 in etc) to see if I can make any sense of this.

:scratch:
Last edited by PistolPatch on 08 Jul 2016, 09:39, edited 1 time in total.
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Post #9 made 7 years ago
by PistolPatch
I should have explained how the two piece bungs work.

Both parts are made of silicone that has some flexibility to it. In other words, the "mushroom" part is very flexible and bendy. To assemble, the stalk of the mushroom is pulled through the centre hole. The mushroom head then covers the other four holes which are bored all the way through the bung. In other words, if you peel up the mushroom head, you can see through the hole into the wort.

The above also means that there are four holes for pressure to escape through. There just needs to be enough pressure to overcome the flexibility of the mushroom head.

The four holes can also be used for other things. For example, in the first pic, I have a thermowell (stainless steel tube with the end sealed) in one of the holes. This allows me to insert a thermometer probe to measure the wort temperature. That still leaves four holes for the CO2 to escape via though.

Busy for another few days but am looking forward to trying to work this out.
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(Old Hands) - Figure this one out!

Post #10 made 7 years ago
by Contrarian
Was this the saison that you were fermenting? Some ferments are more vigorous than others and I'm wondering if that is among a difference.

Even with the holes etc there would be a limit to the volume of gas that could flow through the bung over a period of time. If the has being produced by the ferment was greater than what could be vented over a period of time the pressure would build up within the system.

I'm sure it would be possible to calculate the flow rate through the bung with reasonable accuracy and then extrapolate whether the fermenting wort could produce gas at a rate that would overwhelm the system.

It is possible with an ale or lager ferment this wouldn't happen but with a more hectic saison or hefe ferment that it might.

It is also possible that no gas was escaping for some reason and that everything above is completely pointless!

Post #12 made 7 years ago
by Rick
goulaigan wrote:Oddly enough, like Rick I have also experienced this with blowoff tubes. No idea why either. This is while the blowoff is bubbling away in the jar of starsan, if i push the lid down the bubbling stops for a while then starts back up as the lid starts to bulge again... Never had a lid come off yet thankfully but definitely bulge at least a couple cm... And the tube I use is larger than any of my airlocks...
Yep, this is normal behavior for me. I'll push down out of fear it'll explode, bubbles like crazy in the process ... only to just build up again.

I can't nail it down to fast ferment, because I only use a blow off on my bigger beers being fermented with wyeast 1028 (which is quick). Of course, I have nothing to compare that against, as airlocks are used in every other scenario for me.
Last edited by Rick on 08 Jul 2016, 20:04, edited 1 time in total.
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Post #13 made 7 years ago
by goulaigan
I only use a blowoff on vigorous beers that fill my airlock with yeast goo or spit the airlock out completely. Contrarian may be on to something there at least in my situation, not sure about PPs tho...
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Post #14 made 7 years ago
by PistolPatch
Contrarian wrote:Was this the saison that you were fermenting? Some ferments are more vigorous than others...
Sorry for the slow answer mate - still under the pump :evil:.

It wasn't the saison :nup:. It was an IPA an no ferocious ferment.

The holes in the bungs are about 7mm and there are four of them which means heaps more flow than a normal air-lock. I haven't had time to do, let alone think of an experiment to do on this problem.

For now, I'm with Todd on aliens being the answer :smoke:.
Last edited by PistolPatch on 17 Jul 2016, 21:36, edited 1 time in total.
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Re: (Old Hands) - Figure this one out!

Post #15 made 6 years ago
by PistolPatch
This one still has me :scratch:

Brewed 2 x 1.5 batches on Wednesday with Sarah. So, ended up with 3 fermenters each with two "bungs." Same problem. (You reckon at least one of the bungs on each fermenter would work?)

Tried: loosening the bungs; loosening the 'mushroom' cap; and putting some olive oil in between cap and bung body. No result.

It's amazing how quickly the pressure builds up and just how much it builds up. And, very weird how a simple slight peeling back of the 'mushroom' cap releases the pressure. Silicone is one of the least "perishable" substances around but all I can think of is that it has become less flexible.
:smoke:

Anyway, gave up and did the following temporary fix :) ...
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Re: (Old Hands) - Figure this one out!

Post #16 made 6 years ago
by jhough
PP, sometimes best not to overthink things...I'm not familiar with the lid setup in original pic, but, could there be a blockage in the center bung causing excess psi ? Combo of that and the yeast strain . I've been told by wiser mechanics to stop overthinking things and go back to basics.
Like the corp. president that wanted to increase sales of a toothpaste. All the whizkid marketing gurus failed. A janitor told him "make the hole bigger". AIM toothpaste sales tripled and the janitor became a vice -prez. Sometimes go to the KISS meathod. Keep It Simple Stupid.
J
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Re: (Old Hands) - Figure this one out!

Post #17 made 6 years ago
by PistolPatch
Problem Solved!

Hey Joe :peace:

Sorry for my slow response but I wanted to wait until my fermenters were empty so I could test the bungs. I did that this morning and still had no answer...

I blew through the bungs and they released.
I jammed them into the fermenter lid and blew threw them and they released.

:scratch:

Then, not just ten minutes ago, I had a :idea:... It dawned on me that I had changed from "screw-lid" plastic fermenters to "pail/bucket" type fermenters. So, I then went and 'pushed' the pail lids to see if they were really flexible. They aren't. I was disappointed :dunno:

Then, as one final test, I re-assembled the fermenter, with the two bungs, and blew in one. The lid rose up dramatically but the air-lock did release :champ:

So, for me at least, this is an interesting story....

Sometimes it is hard to see the simple answer, but, even in hindsight, I'm not sure I would have seen it. It never clicked to me until tonight that before I was using different fermenters. But, even if it had clicked, the last 'culprit' I would have suspected was the different fermenters. Why? Because I naturally assumed my silcone air-locks were pretty much like bubble air-locks - the slightest difference in pressure would activate them. The rigidity of my old fermenters did not show just how amazing these air-locks are....

They are amazing. Consider that they hold in place (don't just pop out) under considerable pressure and, they do actually release. Seven days ago, I said to Sarah, "It's amazing how quickly the lid bulges, just an hour after I release it manually, the lid has bulged again." At that point, I hadn't realised they were releasing, I'd just panicked and manually released them in fear that the whole lid of the fermenter would blow off!

So, the answer was simple but still very hard to find. The main reason it was hard to find was that these bungs are relatively new and, most brewers at time of writing, won't be using pails/buckets. If the combination of these two were normal (and that combo has huge advantages) then I would have read, a hundred times, "Your lid will swell dramatically. Don't worry. That's normal."

Today has been good. Solved that plus a few other big things.

:champ:
PP
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