My new dry hopping method!

Help Support The HomeBrew Forum:

ssashton

Well-Known Member
Joined
Apr 17, 2019
Messages
198
Reaction score
62
I've realised that many of my past beers have been hindered by oxygen at some point, even though many were quite drinkable. So I'm on a bit of a quest to be rid of the damn stuff!

To this end I have attempted to make a device which allows me to dry hop without opening the fermenter. I use a plastic pressure barrel (Wilko) to ferment at around 10psi, but this would work on anything you can drill a 26mm hole in.

20210905_232903.jpg


The idea I think is pretty basic, like an air-lock for hop pellets - put a large diameter ball valve on the fermenter. Attach a bottle to it that can be filled with hop pellets, purged with Co2, sealed, then opened to the fermenter.

To attach to the body of the fermenter I ordered a 3/4" BSP (that's the screw thread spec) ball valve with bulkhead fitting sold for rain water butts.

Untitled-2.jpg


At first I thought about joining it to a coke bottle or similar, but I wasn't sure what thread they have. I also wanted to mount a Schrader valve inlet for CO2 to purge the hops but the thin curved body of a coke bottle could make that difficult.

Instead I decided to 3D print a container in PLA! (Entry level 3D printers are under £200, not unobtanium these days). The advantage here is that I can design it exactly the way I want, but it did take 12 hours to print. I designed in the 3/4 BSP thread on the bottom, a conical shape to channel the hops, a flat area to mount a CO2 inlet and a large screw cap with 32mm hex top for tightening. I also came back later and added flat mating seals on all the threads which I printed in TPU rubber.

Untitled-1.png


I put it all together, tested it out and... FAIL! :(

Firstly the hopper didn't hold pressure for more than a few seconds, secondly the hops didn't flow through!

I added the seals to the screw parts and... still no pressure holding. So, I added a coat of varnish to the outside and then it did, yay!

I primed it with 50g of hop pellets and charged to 30psi with CO2. I opened the ball valve as fast as I could but still only 1/3 of the hops went in! After a couple practices I found just repeatedly tapping the container got all the hop pellets to fall through. So okay, bit of percussive maintenance is easy to perform. Even if I had to open the top cap of the hopper and push the pellets though with a stick, I think provided I have a running stream of CO2 on that Schrader valve near the opening of the fermenter I will get next to no oxygen in going in. So I'm pleased!

20210905_232910.jpg


If anybody wants to follow me on this weird DIY journey, I'll pop the files for the hopper bottle on Thingiverse, just ask.

Now I have a question - Can I add the hop pellets directly to the beer? I've used a rubber band to tie a hop sock on the inlet, but I'm not sure how well it will stay on or if it will stop the hops getting full contact. Does anybody use hop pellets added them directly to the fermenter? How do you get them out of the beer? Does a cold crash do a good job of dropping all the particles out?

20210905_200302.jpg
 

RoomWithABrew

Landlord.
Joined
Apr 19, 2021
Messages
580
Reaction score
330
Location
Paremata New Zealand
This is a variant of the ballvalve and pet bottle attachment made by kegland for the tops of fermzillas.

It looked the part but didn't perform that well from reports I read on the american forum.

FWIW I just put the hops in a bag with a vac sealed normal magnet in the bag. Use a neodynium magnet on the outside ( upcycled from an old Hard disk drive).
This is magneted on the fermenter at the start of ferment or put in after high krausen.
Then when dry hop time just slide it down into the beer, this ensures they get fully immersed , you can swish the hops about in the bag and bring them out of the beer at the time you decide.
Works well. This picture before I upgraded to the HDD magnets as first time didn't have any and just dropped the hops, but they didn't sink well.
IMG_20201108_170431.jpg
 

foxy

Landlord.
Joined
Nov 12, 2013
Messages
3,725
Reaction score
2,503
In 2018 I made this similar idea, now I just open the lid and throw them in. There is no mass exodus of co2 and not enough oxygen intake to worry the beer. I blame retirement and lock downs especially for those with an engineering background. It makes us tend to overthink things, I,would never critisise Buffers Brewery, what he does is it keeps his mind working even when there is no need. Engineers tend to look for things which aren't there.
034.JPG
 

The-Engineer-That-Brews

Tinkering around
Supporting Member
Joined
Jul 27, 2020
Messages
2,611
Reaction score
2,376
Location
St Albans, Herts
I've realised that many of my past beers have been hindered by oxygen at some point, even though many were quite drinkable. So I'm on a bit of a quest to be rid of the damn stuff!

To this end I have attempted to make a device which allows me to dry hop without opening the fermenter. I use a plastic pressure barrel (Wilko) to ferment at around 10psi, but this would work on anything you can drill a 26mm hole in.

View attachment 53892

The idea I think is pretty basic, like an air-lock for hop pellets - put a large diameter ball valve on the fermenter. Attach a bottle to it that can be filled with hop pellets, purged with Co2, sealed, then opened to the fermenter.

To attach to the body of the fermenter I ordered a 3/4" BSP (that's the screw thread spec) ball valve with bulkhead fitting sold for rain water butts.

View attachment 53890

At first I thought about joining it to a coke bottle or similar, but I wasn't sure what thread they have. I also wanted to mount a Schrader valve inlet for CO2 to purge the hops but the thin curved body of a coke bottle could make that difficult.

Instead I decided to 3D print a container in PLA! (Entry level 3D printers are under £200, not unobtanium these days). The advantage here is that I can design it exactly the way I want, but it did take 12 hours to print. I designed in the 3/4 BSP thread on the bottom, a conical shape to channel the hops, a flat area to mount a CO2 inlet and a large screw cap with 32mm hex top for tightening. I also came back later and added flat mating seals on all the threads which I printed in TPU rubber.

View attachment 53891

I put it all together, tested it out and... FAIL! :(

Firstly the hopper didn't hold pressure for more than a few seconds, secondly the hops didn't flow through!

I added the seals to the screw parts and... still no pressure holding. So, I added a coat of varnish to the outside and then it did, yay!

I primed it with 50g of hop pellets and charged to 30psi with CO2. I opened the ball valve as fast as I could but still only 1/3 of the hops went in! After a couple practices I found just repeatedly tapping the container got all the hop pellets to fall through. So okay, bit of percussive maintenance is easy to perform. Even if I had to open the top cap of the hopper and push the pellets though with a stick, I think provided I have a running stream of CO2 on that Schrader valve near the opening of the fermenter I will get next to no oxygen in going in. So I'm pleased!

View attachment 53894

If anybody wants to follow me on this weird DIY journey, I'll pop the files for the hopper bottle on Thingiverse, just ask.

Now I have a question - Can I add the hop pellets directly to the beer? I've used a rubber band to tie a hop sock on the inlet, but I'm not sure how well it will stay on or if it will stop the hops getting full contact. Does anybody use hop pellets added them directly to the fermenter? How do you get them out of the beer? Does a cold crash do a good job of dropping all the particles out?

View attachment 53893
I like your thinking, and great job on the construction athumb..
FWIW here are the specs for the threads found on PET bottles: https://myplasticmold.com/wp-content/uploads/2012/07/PET-preform-neck-finish-catagories.pdf

Perhaps the coke bottles might be this one...

Screenshot 2021-09-06 at 08.13.57.png
 

Buffers brewery

Complicated Brewer
Supporting Member
Joined
Dec 11, 2019
Messages
1,623
Reaction score
1,346
Location
Bognor Regis
In 2018 I made this similar idea, now I just open the lid and throw them in. There is no mass exodus of co2 and not enough oxygen intake to worry the beer. I blame retirement and lock downs especially for those with an engineering background. It makes us tend to overthink things, I,would never critisise Buffers Brewery, what he does is it keeps his mind working even when there is no need. Engineers tend to look for things which aren't there.
View attachment 53899
Cheers @foxy acheers.

But the fact that you devised a piece of kit suggests that at one time you could see a benefit, but you couldn’t be a***d to keep it up :laugh8:

Did you see my thread on a design for the Fermzilla? Suffered the same fate as the OP and was porous. Tried shellac with no success. What laquer did you use @ssashton
 

Buffers brewery

Complicated Brewer
Supporting Member
Joined
Dec 11, 2019
Messages
1,623
Reaction score
1,346
Location
Bognor Regis
Nice work @ssashton athumb..

The dry hopper I designed for a Fermzilla used an inverted conical hopper so when the trap door was opened all the hops fall straight out. No taper to restrict them. You could go down the same route and design an extension that fits the barrel cap thread giving you a larger diameter to work with. The hops get loaded in after pitching the yeast and are naturally purged of O2 during fermentation.

This is my effort on a friends Fermzilla

DF31F2A1-E233-4B1F-B84F-25666DD51876.jpeg

This is what the innerds look like...
E075B489-0887-4B64-8CBF-8974E1CDF4ED.jpeg
 

RoomWithABrew

Landlord.
Joined
Apr 19, 2021
Messages
580
Reaction score
330
Location
Paremata New Zealand
I like your thinking, and great job on the construction athumb..
FWIW here are the specs for the threads found on PET bottles: https://myplasticmold.com/wp-content/uploads/2012/07/PET-preform-neck-finish-catagories.pdf

Perhaps the coke bottles might be this one...

View attachment 53901
I think you're right.

Any chance your thread database has a profile for the threads on a Petling xxl bottle that's used for holding an Ispindel?
A 3d printed solid cap that doesn''t deform under pressure like the standard tops would be a boon.
 

The-Engineer-That-Brews

Tinkering around
Supporting Member
Joined
Jul 27, 2020
Messages
2,611
Reaction score
2,376
Location
St Albans, Herts
Any chance your thread database has a profile for the threads on a Petling xxl bottle that's used for holding an Ispindel?
A 3d printed solid cap that doesn''t deform under pressure like the standard tops would be a boon.
It depends what type of bottle the Petling (bottle preform) was going to be made into... it's very likely to be one of the ones shown on that page I linked though.
If you want a solid cap with a matching thread then I'd be tempted to make a mould and cast it (@Buffers brewery is the expert on that); however if you want to 3D print it then I think you'll find a suitable 3D model here: "pet bottle thread" 3D Models to Print - yeggi
 

Druncan

Senior Moments
Supporting Member
Joined
Apr 15, 2016
Messages
764
Reaction score
355
Location
Isle of Tiree, Inner Hebrides
Curious, @ssashton I'm going down the same dry hop route. athumb.. But I have also found most of the flavour stops in the T90's I only get that if I wring the bag,,, and add the liquor to the keg,,, = FV dry hopping seemed very inefficient. FYI I also salvage CO2 during high krausen in 20l wine bags to purge everything. What I really wanted to add all the flavour as I keg from the FV. As this seemed to pose even less risk.

Then experimented with my hop-rocket + bag and substituting cold water for my brews. Good flavour! then added rice hulls to stop compaction, even better and no flavour left in the T90's. Now trying hot water to pre-dissolve the t90s. This seems to work even better, instant T90 breakdown!! Just need a simple re-charge method for the hop rocket each keg full,,,,
 

Buffers brewery

Complicated Brewer
Supporting Member
Joined
Dec 11, 2019
Messages
1,623
Reaction score
1,346
Location
Bognor Regis

ssashton

Well-Known Member
Joined
Apr 17, 2019
Messages
198
Reaction score
62
Wow lots of cool ideas here!

I used a Sayerlack 2 part varnish (because I had it), so it sets much like an epoxy glue. I'm sure any 'yacht varnish' would also work just take longer to cure.

I like the idea of vacuum sealing a magnet! I did think of using a magnet or maybe thin thread to hold the hops inside the FV, but someone mentioned hops getting damp and I wasn't sure what that would do to the flavour.

I really like the trap-door top cap extension too! It looks like a really smart design. How do you open the door? I might try something similar, but I'm also a little worried about getting it to seal. Even the original cap doesn't seal unless super tight and lubed up on these Wilko ones.

Finally wow, I never even though of in-line hopping, which looks like what the 'hop rocket' is doing. Does the flavour really get in during such a short time as a vessel transfer? Or do you do it on serving?

No comments on how well hop pellets drop out with a cold crash or finings if I don't use a sock?

I'm getting worried the elastic band could fall in once the hops get heavy. I think I'll pull it out now (12 hr after pitch) when hopefully fermentation is not oxygen sensitive yet.
 
Last edited:

Buffers brewery

Complicated Brewer
Supporting Member
Joined
Dec 11, 2019
Messages
1,623
Reaction score
1,346
Location
Bognor Regis
I really like the trap-door top cap extension too! It looks like a really smart design. How do you open the door?
 

ssashton

Well-Known Member
Joined
Apr 17, 2019
Messages
198
Reaction score
62
P.S. As well as the varnish, I printed everything solid, '100% infill' essentially.
 

Buffers brewery

Complicated Brewer
Supporting Member
Joined
Dec 11, 2019
Messages
1,623
Reaction score
1,346
Location
Bognor Regis
Yes, as did I, but with PETG filament. Being a higher temperature filament I wonder if that prevented the layers/infill from sticking together consistently.
 

ssashton

Well-Known Member
Joined
Apr 17, 2019
Messages
198
Reaction score
62
Yes, as did I, but with PETG filament. Being a higher temperature filament I wonder if that prevented the layers/infill from sticking together consistently.
I think the plastics must be slightly porous to the molecule size of CO2 / nitrogen and once the pressure gets higher than a few psi it becomes noticeable. I have printed solid enclosures for speaker tweeters that needed to be 'air tight' and tested them by sucking on the back with a vacuum cleaner. They worked well provided no printing issues. However in that case the area was small and a vacuum cleaner doesn't 'suck' very hard about 3 psi.

If you want some of my varnish and hardener I can send some for cost of postage. I've got a 5L pot and will not likely use it.
 

Buffers brewery

Complicated Brewer
Supporting Member
Joined
Dec 11, 2019
Messages
1,623
Reaction score
1,346
Location
Bognor Regis
Thanks for the offer @ssashton but I’m not planning on making another one as I don’t have a Fermzilla :laugh8:
I did the project for another member and he now has the .STL files for all the parts and I think is printing the parts himself.
 

RoomWithABrew

Landlord.
Joined
Apr 19, 2021
Messages
580
Reaction score
330
Location
Paremata New Zealand
It depends what type of bottle the Petling (bottle preform) was going to be made into... it's very likely to be one of the ones shown on that page I linked though.
If you want a solid cap with a matching thread then I'd be tempted to make a mould and cast it (@Buffers brewery is the expert on that); however if you want to 3D print it then I think you'll find a suitable 3D model here: "pet bottle thread" 3D Models to Print - yeggi
Thanks plenty to look at there and consider. The final bottles made with the petling former are 2litre milk plastic bottle size. Diameter of the outside of lid is 39 mm and the petling it fits onto has a 36mm diameter with a 1.5mm thick wall.
@ssashton
The hops get a little damp I suppose but certainly don't go off in the few days they hang around in the bag.

I find that the hops pellets do get out of my bags because I'm using net curtain like material. It certainly drops to the bottom of the conical and into the fermentasaurus bottle, i use the bag and magnet to swish it all around so that it gets good contact everywhere. Not had a problem fining it either, I get it cold before doing that.

Have just bought a hop missile to use as hop back, trub filter and could use it as an inline randall as well, but I've already got this which I use for closed oxygen free dosing of finings etc and can use as a randall either inline during bottling or in the keg fridge. It does impart that aroma for sure.

I have modded the hop injector with a universal keg post on the top and have fitted a liquid ball lock connector to the bottom. That way I can flush out sanitiser, fill with beer, fill with finings or put hops in and purge then use it. Works well.

I suppose the best thing would be a little airtight box with magnet to hold it on fermenter / keg wall and a means of opening it perhaps via another magnet to drop the hops in so keeping them from getting damp. More cadding and ingenuity solutions.
 
Top