Your experience with PET Pressure Fermenters - Open Discussion - feedback invited

[CKK]

With PET Fermenters finding homes in many a brewer's den it would be great to get feedback about our Unitanks etc. No point to avoid the obvious which is that we have concerns about PET vessels getting a bad rap with some people as almost daily we receive pictures of disasters from all around the world. Luckily they are rarely if ever ours. It is still a problem for us however as potential customers easily confuse products from different suppliers and when they see stuff that at best leaks a lot or worst explodes and causes injury then many are put off any kind of PET tank. We want to help overcome this and show brewers around the world that high quality PET tanks are perfect for their activities and can save them the expense of stainless steel. Primarily we are interested in PET tanks that work under pressure. Its easy to make a PET vessel that does not need to hold pressure. Much harder to get one to go to 5 bar or more but not impossible. Keep in mind that with PRVs which release at 35 psi that this is the pressure that most car tires operate at so there is a lot of energy. To contain this safely the design and production of the tank requires not only the right machinery but also an expert understanding of the materials and processes.

So please let us know your experiences here and help us do better. Our team is very proud of the high quality tanks that we make right here in Melbourne but its always possible for a problem to occur. If problems do happen we are very keen to quickly analyse what happened and use this to improve.

Over to you and please tell us your wishes if you are thinking to get one or about your usage experience if you already have one. Would love to see pictures.

 

[Fro-Daddy]

I have the original Fermentasaurus and a 60L All Rounder (which I've only used twice).

Most of the Fermentasaurus issues have already been addressed as it has been out for a long time. The main one being the tiny butterfly valve. I've never bothered to upgrade this as I rarely harvest yeast as much as I thought I would. I also don't pull it apart ever for a deep clean (because it's difficult), I just let it soak and everything is fine.

With the All Rounder, getting the posts and PRV to seal was fiddly on mine. I've now added thread tape but haven't used it since. The Fermentasaurus posts are much better.

 

[BKBrews]

I think the biggest issue I have with pressure tanks is what it has done to the homebrew scene - you join any homebrew facebook group and it is just full of people asking questions about how they can brew beers at the max psi ratings for the tanks. It's ridiculous.

I would personally prefer a stronger and more issue free tank that can hold much less pressure than the current options are rated for. I will admit I have tried pressure fermenting (never above 10psi - just because I can - not for me), but the reality is I bought these tanks so that I could dump yeast/trub, and then pressure transfer to kegs at low pressure. The ability to carbonate in tank (at 10-12psi and 2-3 degrees) is a nice to have, but really not a major factor when I can do the same after keg transfer.

The ultimate tank for me would be super strong, 15psi max pressure, stainless fittings on the bottom with tri-clover dump valve (I'd compromise with some plastic tri-clover options including bends etc, and a lid that has gas in post, liquid out post, thermowell, and a nice big port for a blow off tube.

I was gifted a fermzilla and have had nothing but issues with it. I have been planning to try the G3, but to be honest I think I'm ready to just bite the bullet and go stainless.

 

[soreba]

The ultimate tank for me would be super strong, 15psi max pressure, stainless fittings on the bottom with tri-clover dump valve (I'd compromise with some plastic tri-clover options including bends etc, and a lid that has gas in post, liquid out post, thermowell, and a nice big port for a blow off tube.

This ^^. No idea why the homebrew scene prefers crappy plastic taps and unsanitary threads over tc fittings. Im guessing its an expense thing.

The most annoying thing for my on my Fermzilla (and looks like a similar setup on the saurus) is the bottom rubber gasket... there is 4 or 5 pieces in total at the bottom with reverse threads etc and is an absolute pia to remove. So i dont remove it often (when it probably should be for cleaning). Ideally a 3 inch triclamp at the bottom would be my preference - Similar to the Malt Mechanics HDPE conical.

Edit: Also, in regards to PET pressure. I am expecting catastrophic failure as the unit gets older and older

 

[clickeral]

I currently have 2 Snubnose 35L, about to keg the 2nd brew out of one and the other has been used for dryhopping my first brew.

Will be upgrading to Thermowell lids for better temp monitoring/control (also less ugly then a probe cable tied behind polystyrene on the side)

Only challenges so far have been

• The floating dip tube getting stuck on the side or pointing up (may need to look into the washer/weighting mod for this, but haven't yet)
• One of the valve not being assembled correctly (2min job to fix and people should know these need cleaning etc before use)
• Measurement sticker isnt the easyist to apply and no instructions in box on where it should go (I worked it out)
• Not being able to use boiling/hot water, I have adjusted my cleaning methods for this but I do miss being able to just put boiling liquid into my fermenter, also means you need to have some way to chill your wort before you put it into the fermentor
• Based on mixed comments online I don't leave starsan style products in mine so might pay to confirm if this is ok or not, some instructions in the box with some quick guides or notes might be useful
• Transfers can be slow (suspect this is user error on my part and I need to adjust what psi I transfer at etc)
• My main fridge isnt tall enough to fit 2 due to the compressor hump and my 2nd fridge is just aliitle short due to the control being on the roof (not your fault however, I would be keen to see a short 90degree gas post at similar height to the current gaspost height (I cant get a metal gas fitting onto the post ) my 3rd fridge would fit one but its too wide to be in the shed and I am not keen to use it atm as its setup as my drinks fridge and will be getting a keg moved into it this weekend

Otherwise really happy, I ferment at up to 25psi and can get closed oxygen transfers without issue, closed transfer (no oxygen) dry hopping has been great. Managed to do a closed transfer gelatin addition this morning. Have also been terrible at drinking direct out of the fermentor rather then moving it to a keg unless I need to use it for another brew

It being clear helps keep an eye on whats happening fermentation wise, however it wasn't the main driver and at some point ill be getting some bigger stainless unitanks but its a good price point, however I still think people who are just starting to brew should give the old plastic fermentors a go first as they are pretty forgiving

35L is a good size as my min batch on my 3v is roughly 25L and I am still dialing it in so have had upto 32L into the fermentor without issue

Will be putting two more brews down this weekend so will report back

Havent had any vaccuming or stress cracks or anything like that, the lids are easy to get on and off. I also remove the spunding valve and cold crash so glad it hasn't caused any issues

 

[mynameisrodney]

For me, I'm not interested in one with a dump valve. I think even a great design can get leaks, and it's just something I'd rather not have to worry about. Especially seeing as by the time my beer is going into the fermenter I've usually had a few to drink too. Obviously other people will want those products, I'm not try to say stop making them, I just don't plan on buying one.

I've been using an all rounder for I think 12 or so brews and I'm very happy with it, but it's not perfect. Looking at your new stubby thing coming out it has a few advantages in that I could most likely fit 2 in my ferm fridge rather than 1. What I don't like about it is that the lid looks too small to fit my hand in. I think with a bigger lid this would be pretty close to the perfect fermenter for me.

In terms of failed fermenters, pressure fermenting is more complex than normal brewing and there are more things to stuff up. Once a product gets a bad rep, people are more inclined to publicly voice their failures and blame the product rather than their own actions. A lot of the failures I have seen appear to be from misuse. Yes, a perfect product should be designed so that it can't get misused, but that doesn't mean that user error is not a factor.

You see this with many products. One that springs to mind is ROTA wheels. They got a bad rep as being cheap, and now you see posts everywhere from p platers saying stuff like "I drifted my car into a gutter and my ROTA wheel broke. ROTA wheels are crap." The circle jerk is strong, and gives them something to blame other than their own actions. If they were more expensive wheels that didn't give them the same scapegoat, they wouldn't be plastering it over Facebook etc.

 

[mynameisrodney]

• Not being able to use boiling/hot water, I have adjusted my cleaning methods for this but I do miss being able to just put boiling liquid into my fermenter, also means you need to have some way to chill your wort before you put it into the fermentor

This is a very good point and one that I also miss.

 

[clickeral]

For me, I'm not interested in one with a dump valve. I think even a great design can get leaks, and it's just something I'd rather not have to worry about. Especially seeing as by the time my beer is going into the fermenter I've usually had a few to drink too. Obviously other people will want those products, I'm not try to say stop making them, I just don't plan on buying one.

I've been using an all rounder for I think 12 or so brews and I'm very happy with it, but it's not perfect. Looking at your new stubby thing coming out it has a few advantages in that I could most likely fit 2 in my ferm fridge rather than 1.

In terms of failed fermenters, pressure fermenting is more complex than normal brewing and there are more things to stuff up. Once a product gets a bad rep, people are more inclined to publicly voice their failures and blame the product rather than their own actions. A lot of the failures I have seen appear to be from misuse. Yes, a perfect product should be designed so that it can't get misused, but that doesn't mean that user error is not a factor.

You see this with many products. One that springs to mind is ROTA wheels. They got a bad rep as being cheap, and now you see posts everywhere from p platers saying stuff like "I drifted my car into a gutter and my ROTA wheel broke. ROTA wheels are crap." The circle jerk is strong, and gives them something to blame other than their own actions. If they were more expensive wheels that didn't give them the same scapegoat, they wouldn't be plastering it over Facebook etc.

This is a very good point and one that I also miss.

I agree with your points, if the Stubby would allow me to run two at once I would buy 2 as well (would still use the 2 snubnoses I have atm as well)

To your Rota wheels point I think its excellent, Ive had brand name wheels which I have hit the kerb with and they also broke (whole center broke from the barrel) however this prevented the car from flipping and more suspension damage from occurring, but because people haven't expirenced it they blame the product.

Alot more people are getting into homebrew (both beer and spirits) the hobby has never been more accessible but we all need to remember it can also be very dangerous when people don't use good judgement and learn correct process.

Its quite easy to seriously injure yourself at many steps of a brewday, I would say these plastic unitanks are not for a new brewer in my view as you really cant take shortcuts with them.

Not to say that stainless doesnt also have disadvantages but I wouldnt recommend a stainless fermentor to a new brewer either

 

[wide eyed and legless]

For me, I'm not interested in one with a dump valve. I think even a great design can get leaks, and it's just something I'd rather not have to worry about. Especially seeing as by the time my beer is going into the fermenter I've usually had a few to drink too. Obviously other people will want those products, I'm not try to say stop making them, I just don't plan on buying one.

In terms of failed fermenters, pressure fermenting is more complex than normal brewing and there are more things to stuff up. Once a product gets a bad rep, people are more inclined to publicly voice their failures and blame the product rather than their own actions. A lot of the failures I have seen appear to be from misuse. Yes, a perfect product should be designed so that it can't get misused, but that doesn't mean that user error is not a factor.

I wouldn't say pressure fermenting is more complex, nor would I be blaming the user of the Fermzilla. The design and manufacturing is at fault, yes we have seen users close the dump valve and the collection bottle explodes, poor design and choice of material. I would say that owners of the fermenasaurus would have inadvertently closed the dump valve but we haven't witnessed the catastrophes we have with the FermZilla.
As for the snub nose that suits my purpose down to the ground, I had my stint at pressure fermenting and it just wasn't right for the majority of beers I make. I can dry hop the secondary Snubby and transfer with no bother.
The cone over the bigger surface area of the allrounder, simple school boy physics of the elephant and a stiletto heeled woman, more pressure over a smaller area results in a more compact yeast cake at the bottom of the fermenter = more beer out.

 

[BKBrews]

I wouldn't say pressure fermenting is more complex, nor would I be blaming the user of the Fermzilla. The design and manufacturing is at fault, yes we have seen users close the dump valve and the collection bottle explodes, poor design and choice of material. I would say that owners of the fermenasaurus would have inadvertently closed the dump valve but we haven't witnessed the catastrophes we have with the FermZilla.

To this point, and I admit I have never used the equivalent Keg King product, but one of the faults with my fermzilla was stress marks all around the lid mouth after less than 10 batches (closer to 5). And like I said in my post, I never used in excess of 10psi for any part of the process. Not withstanding the physical dangers, I am currently living in an a rented apartment, and if I lost 25L of beer all over the balcony (and probably off the balcony to the unit below) that would be catastrophic.

 

[kadmium]

I personally don't think the port needs to be big enough to fit your hand inside. If you're going to use these tanks, you're doing yourself a disservice if you don't make yourself up a cheap pond pump CIP system. With the Atomic ABC or PBW or what ever percarb cleaner you prefer, I literally take my Snub Nose, pop it over the outlet upside down on my bucket blaster (the one from KL and KK are the same thing really) and let it clean for 10 minutes. I then rinse with the garden hose and bobs your uncle.

Crystal clean, no beer stone, no nothing. By having a large opening, you are only encouraging people who don't know better to stick their hands inside and clean it. This isn't needed, and will create micro abrasions for infections to live in. So, I don't see the point of a bigger opening. And if you look at the units which are having issues, they have big openings up the top. The larger they are, the weaker that point. It's why you don't see an airplane with floor to ceiling windows.

Just my opinion, and everyone is different, but if you want to design a product that is safe, and minimises the risks to people who don't know better, I think a smaller opening is the right move. The cone shape does indeed provide a better volume of clean beer at the end of ferment, however it comes at the price of being taller. As such, the rounder will suit some people, and the snub others.

Also, I don't think you should add a separate blow off port, as the vast majority of people who use these, ferment under pressure. This keeps the krausen down, and if you stick to the limits indicated on the fermenter, you won't need a blow off. If you do feel like you absolutely need one, then simply rigging a disconnect up to the gas post with a piece of beer line is a blow off done. One less opening / possible weak point.



In relation to producing them to a 'lower' pressure rating, I don't see the point. If it's rated to 2.4 bar or 35PSI and people want to run on the knife edge that's up to them. They also shouldn't undergo 'catastrophic failure' unless you have gone past the 2 year mark and have not had it pressure tested as it tells you to do ON THE FERMENTOR.

So, why create a product that is PET, light weight, with gas posts and liquid posts and then only construct it to handle low pressure? Doesn't make sense. It's like saying all cars should only have enough power to reach, and maintain 110kmh. As that is the upper limit. Why bother having more powerful cars? You don't need it, and people only end up driving at the end of the power range, and sliding their cars into gutters. It's not the cars fault, it's the driver.

 

[dkril]

Is there a reason no PET unitank has a triclamp fitting as an integral part of its design? Is PET not a suitable material? Not compatible with the manufacturing process? Cost? Size and bulk?

 

[CKK]

I have the original Fermentasaurus and a 60L All Rounder (which I've only used twice).

Most of the Fermentasaurus issues have already been addressed as it has been out for a long time. The main one being the tiny butterfly valve. I've never bothered to upgrade this as I rarely harvest yeast as much as I thought I would. I also don't pull it apart ever for a deep clean (because it's difficult), I just let it soak and everything is fine.

With the All Rounder, getting the posts and PRV to seal was fiddly on mine. I've now added thread tape but haven't used it since. The Fermentasaurus posts are much better.

Well you can still easily update your old FS or if its too old turn it into a grainary. For the All Rounder just be careful with pressure as from what we have seen on these vessels that they have stress cracks. Not sure if they are the same lid as their other units but if so then you will find our gen 3 lids will fit them and it is a better quality lid. Let’s you use our other accessories like dry hopping port, Thermowell and our much cheaper cooling/warming coil.

Pictures below will show you the advantages apart from the chill/warm coil not shown. The pickup ball is tethered to the Thermowell so less chance to end up on the sides. Best spot to get the clean beer. The dry hop port is under the PRV. Also not shown is the CIP spray ball which can attach to the lid inside for use of our cleaning system.

 

[Fro-Daddy]

You have a Fermzilla! Do you feel dirty?
Good to know that the lid fits, could be a good upgrade for me.

 

[CKK]

I think the biggest issue I have with pressure tanks is what it has done to the homebrew scene - you join any homebrew facebook group and it is just full of people asking questions about how they can brew beers at the max psi ratings for the tanks. It's ridiculous.

I would personally prefer a stronger and more issue free tank that can hold much less pressure than the current options are rated for. I will admit I have tried pressure fermenting (never above 10psi - just because I can - not for me), but the reality is I bought these tanks so that I could dump yeast/trub, and then pressure transfer to kegs at low pressure. The ability to carbonate in tank (at 10-12psi and 2-3 degrees) is a nice to have, but really not a major factor when I can do the same after keg transfer.

The ultimate tank for me would be super strong, 15psi max pressure, stainless fittings on the bottom with tri-clover dump valve (I'd compromise with some plastic tri-clover options including bends etc, and a lid that has gas in post, liquid out post, thermowell, and a nice big port for a blow off tube.

I was gifted a fermzilla and have had nothing but issues with it. I have been planning to try the G3, but to be honest I think I'm ready to just bite the bullet and go stainless.

Not sure if you know but our gen 3 Fermenter Kings come standard with a 2 inch tri-clover adaptor so there is one of your wishes. Our tanks are we believe the strongest on the market today. They easily go to 5 bar during our tests and we have not had one rupture in the field. However just because something withstands 60 psi or more one does not need to ferment at such high pressure. However it is nice to be able to carbonate from 10-35 psi (PRV goes at 35psi) if one wants to. So we have pretty much made available what you would like to have. Not only that we are cheaper than other products on the market and our tanks are Australian Made right here in Melbourne.

 

[CKK]

This ^^. No idea why the homebrew scene prefers crappy plastic taps and unsanitary threads over tc fittings. Im guessing its an expense thing.

The most annoying thing for my on my Fermzilla (and looks like a similar setup on the saurus) is the bottom rubber gasket... there is 4 or 5 pieces in total at the bottom with reverse threads etc and is an absolute pia to remove. So i dont remove it often (when it probably should be for cleaning). Ideally a 3 inch triclamp at the bottom would be my preference - Similar to the Malt Mechanics HDPE conical.

Edit: Also, in regards to PET pressure. I am expecting catastrophic failure as the unit gets older and older

Well no our gen 3 Fermenter Kings are quite different to your FZ and no reverse threads. They are very easy to remove and clean and less parts. You can chuck them in the dishwasher too.

The 2 inch tri clover adaptor comes as standard.

No obstructions like a butterfly valve vane Let’s yeast and trub slide out easily through the circular opening.

 

[mynameisrodney]

I personally don't think the port needs to be big enough to fit your hand inside. If you're going to use these tanks, you're doing yourself a disservice if you don't make yourself up a cheap pond pump CIP system. With the Atomic ABC or PBW or what ever percarb cleaner you prefer, I literally take my Snub Nose, pop it over the outlet upside down on my bucket blaster (the one from KL and KK are the same thing really) and let it clean for 10 minutes. I then rinse with the garden hose and bobs your uncle.

Crystal clean, no beer stone, no nothing. By having a large opening, you are only encouraging people who don't know better to stick their hands inside and clean it. This isn't needed, and will create micro abrasions for infections to live in. So, I don't see the point of a bigger opening. And if you look at the units which are having issues, they have big openings up the top. The larger they are, the weaker that point. It's why you don't see an airplane with floor to ceiling windows.

I don't have a CIP system yep but am planning on getting one. Unfortunately the spray ball was out of stock on my last kk order. There are other reasons for wanting a wider lid such as using hop tubes. I'm not sure mine would fit down the opening in the fkj or new stubby. The fermentersaurus has a bigger lid, so it is doable. As KK ceo points out above they have one that's the same size as the FZ. If a fermenter has a bigger lid than you need/want, there's not really a problem. If its smaller than what you need/want there is a problem.

 

[CKK]

This ^^. No idea why the homebrew scene prefers crappy plastic taps and unsanitary threads over tc fittings. Im guessing its an expense thing.

The most annoying thing for my on my Fermzilla (and looks like a similar setup on the saurus) is the bottom rubber gasket... there is 4 or 5 pieces in total at the bottom with reverse threads etc and is an absolute pia to remove. So i dont remove it often (when it probably should be for cleaning). Ideally a 3 inch triclamp at the bottom would be my preference - Similar to the Malt Mechanics HDPE conical.

Edit: Also, in regards to PET pressure. I am expecting catastrophic failure as the unit gets older and older

Your last point is of course what it is all about. The chance of a catastrophic failure and it occupies our minds a lot. The big worry is about how such a failure occurs. Ideally it should be in the main body and just let the material split open. Yes its lost beer but nothing flies off.

The last picture below is how one of our 60 litre tanks failed under destructive test. You will see the neck area is not really affected. We have since repeated this and the failure mechanism is the same.


The worst scenario is where the failure occurs underneath the neck because then the whole neck including the lid and neck ring can fly off and that could do some serious damage. A few weeks ago a user sent us such a vessel (not one of ours) that he says had 20 psi for transfer when the thing gave way.

What you can see is a lot of large longitudinal cracks and if you look closely in between evidence of numerous small cracks. This is exactly what we do not want to see. If you purchase a new tank then apart from some maybe very tiny stretch marks there should no stress Cracks. If you can see any then do not pressurise it. What happens is that during each pressurisation the whole tank expands and then contracts. If the manufacturing has not been to the right standard then it does not take long for these cracks to grow and render the vessel unsafe.

So one of the reasons I started this thread was the need to show end users that correctly made PET pressure tanks are great for brewers but that we don’t want to get them confused with stuff that has manufacturing issues.

pictures below. It did hit him in the face under the eye he claims but pure luck that no serious injury resulted.

With a PRV fitted that is rated to 35 psi this should simply not happen.

 

[CKK]

I currently have 2 Snubnose 35L, about to keg the 2nd brew out of one and the other has been used for dryhopping my first brew.

Will be upgrading to Thermowell lids for better temp monitoring/control (also less ugly then a probe cable tied behind polystyrene on the side)

Only challenges so far have been

• The floating dip tube getting stuck on the side or pointing up (may need to look into the washer/weighting mod for this, but haven't yet)
• One of the valve not being assembled correctly (2min job to fix and people should know these need cleaning etc before use)
• Measurement sticker isnt the easyist to apply and no instructions in box on where it should go (I worked it out)
• Not being able to use boiling/hot water, I have adjusted my cleaning methods for this but I do miss being able to just put boiling liquid into my fermenter, also means you need to have some way to chill your wort before you put it into the fermentor
• Based on mixed comments online I don't leave starsan style products in mine so might pay to confirm if this is ok or not, some instructions in the box with some quick guides or notes might be useful
• Transfers can be slow (suspect this is user error on my part and I need to adjust what psi I transfer at etc)
• My main fridge isnt tall enough to fit 2 due to the compressor hump and my 2nd fridge is just aliitle short due to the control being on the roof (not your fault however, I would be keen to see a short 90degree gas post at similar height to the current gaspost height (I cant get a metal gas fitting onto the post ) my 3rd fridge would fit one but its too wide to be in the shed and I am not keen to use it atm as its setup as my drinks fridge and will be getting a keg moved into it this weekend

Otherwise really happy, I ferment at up to 25psi and can get closed oxygen transfers without issue, closed transfer (no oxygen) dry hopping has been great. Managed to do a closed transfer gelatin addition this morning. Have also been terrible at drinking direct out of the fermentor rather then moving it to a keg unless I need to use it for another brew

It being clear helps keep an eye on whats happening fermentation wise, however it wasn't the main driver and at some point ill be getting some bigger stainless unitanks but its a good price point, however I still think people who are just starting to brew should give the old plastic fermentors a go first as they are pretty forgiving

35L is a good size as my min batch on my 3v is roughly 25L and I am still dialing it in so have had upto 32L into the fermentor without issue

Will be putting two more brews down this weekend so will report back

Havent had any vaccuming or stress cracks or anything like that, the lids are easy to get on and off. I also remove the spunding valve and cold crash so glad it hasn't caused any issues

View attachment 118985

When you get your Thermowell then of course you tether the pick up float to that and it keeps the beer pickup nicely in the centre of the tank.

 

[CKK]

For me, I'm not interested in one with a dump valve. I think even a great design can get leaks, and it's just something I'd rather not have to worry about. Especially seeing as by the time my beer is going into the fermenter I've usually had a few to drink too. Obviously other people will want those products, I'm not try to say stop making them, I just don't plan on buying one.

I've been using an all rounder for I think 12 or so brews and I'm very happy with it, but it's not perfect. Looking at your new stubby thing coming out it has a few advantages in that I could most likely fit 2 in my ferm fridge rather than 1. What I don't like about it is that the lid looks too small to fit my hand in. I think with a bigger lid this would be pretty close to the perfect fermenter for me.

In terms of failed fermenters, pressure fermenting is more complex than normal brewing and there are more things to stuff up. Once a product gets a bad rep, people are more inclined to publicly voice their failures and blame the product rather than their own actions. A lot of the failures I have seen appear to be from misuse. Yes, a perfect product should be designed so that it can't get misused, but that doesn't mean that user error is not a factor.

You see this with many products. One that springs to mind is ROTA wheels. They got a bad rep as being cheap, and now you see posts everywhere from p platers saying stuff like "I drifted my car into a gutter and my ROTA wheel broke. ROTA wheels are crap." The circle jerk is strong, and gives them something to blame other than their own actions. If they were more expensive wheels that didn't give them the same scapegoat, they wouldn't be plastering it over Facebook etc.

Yes we do get complaints which are sometimes not justified but when stuff actually injures people then we need to look really carefully if this should be sold. Pressure fermenting is actually not that complex and the results are worth the effort. If a user genuinely does something really stupid then its fair to point that out. However the stress cracks in the vessel necks have nothing to do with user error if the thing is sold as a pressure vessel. We cannot say its an error when they pressurised it because they bought it as a pressure fermenter. Leaving a valve closed when fermentation can happen in a collection vessel might be a user error but it is quite a predictable one. So if we expect that then there needs to be a fail safe design. A PRV might do the job. We opted for a PET collection bottle as it will in the very worst case split but not shatter. Better still though our plunger valve design just allows the pressure to lift the valve into the main tank which is of course protected by a PRV.