An internal keg filtering system

You know when you want to move a keg, but you don’t want to stir up the sludge at the bottom;  Or if you want to take a keg to a BBQ or whatever, and you have to transfer it off into another keg to avoid bringing shame to your family name with glasses of haze beer?

Filtering kind of sucks.  It works, but it tends to oxidise the beer, introduce possibility of infection, and prevent any further positive maturation the beer might have otherwise had.  So this fixes at least two of those problems.

Get your filter

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Cut it into 3 slices – you’ll need just one – I used a 1mm angle grinder disc – a drop saw would probably work well also.

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Get some plastic – this is some perspex I had lying around – anything that silicone would stick to is fine.

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Drill an 8mm hole in one of the plastic bits.

Make a nice sandwich with a bunch of silicon.  Jam a length of bev tube in the hole and silicon that up too.  Leave to set for a few days.  Once it has set, I boiled mine in some water for a while to sanitise the whole thing.

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It [i]just so happens[/i] that the dip tube on a corny keg is the exact OD required for our kegging push-in connectors to fit perfectly.  A straight connector is shown, but I ended up with a right angle one since it fit in the bottom of the keg better.

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So, you have to remove the dip tube, slide it up so you can reach the end of it, and attach the connector and filter.  It may take a little stuffing around, but you should be able to get the filter to lie flat on the bottom of the keg.  Reassemble the keg post, and you’re good to go.  Fill with beer from the fermenter.

Here’s the end result.

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This was straight from the fermenter just yesterday – perfectly bright now, and the beer will actually improve over time, which is rather less likely to happen if I filtered it on the way to the keg.

So obviously this is a little silly, but it is a thing that works.  It has some disadvantage in as you can’t really fill the keg through the beer-in connector anymore, as you’d be putting sludge on the wrong side of the filter.  You could, in theory, fill from the gas end, but you’d probably want to tip the keg over to avoid it splashing up in there, and it is altogether kind of awkward.

And I guess the keg might blow a little sooner, but that’s no more beer than what you’d lose filtering it anyhow.

Filtering on the fly

This works: 8HD_3187

It often happens when it would be nice to bring some beer to an event – which usually involves at the very least racking a keg to another, or more often for me, filtering out a recent batch so there is a full keg to bring instead of the 1/2s or 1/3rds of kegs I have sitting in my keg fridge.

The trouble with this is, if the keg isn’t all consumed in one hit, the leftover filtered beer doesn’t have the keeping properties that it would otherwise have – or if I’ve filtered out a very fresh batch, oxidation, or off flavours develop that the yeast would have otherwise consumed.

So doing it on the fly has some benefits:

  • What beer is left remains unmolested
  • Less beer wastage in transfers
  • The filter itself need not be sanitised as thoroughly as it would otherwise be, which saves a lot of effort
  • No process of ultra chilling the beer, cleaning, sanitising and purging the receiving keg, transferring, using up a bunch of CO2, etc etc.

There are some conditions:

  • The flow resistance (long length of tube/stretched tube) must be after the filter, not before.  Otherwise the contents of the filter will empty out into the glass as useless foam.  It helps if this resistance is more than usual too.
  • Once the keg is carbonated, it is good to run top pressure on the keg more than usual – like 20 psi.  This helps to keep the CO2 in solution at all times.  Since this is only for one session the extra pressure won’t overcarb the beer.  The longer tube length will keep the dispense rate appropriate.
  • The filter must be kept upright (so the gas in the filter is at the top), and cold (to keep it from foaming up the beer).

For a transportable keg, I usually put the keg in a empty grain sack, throw in a bag of ice, and put the lot in a flexible laundry basket for easy carrying, and to avoid leaking melted water everywhere.  So I just jammed the filter in the side of the bag along with the ice.

Here is the before and after
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Plastic fermenter mash tun

I’m sure someone has done this before, but I have been using this for quite a few brews lately and it has some advantages.  I have other mash tuns in stainless, false bottoms, etc, but this is pretty good for grists <10kg.  This is only really useful for HERMS type setups.

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There are some details that make it work well so I figured I’m put them here.

I use the heavy duty braid that Nev sells.  This stuff has similar qualities to that you can remove from the Bunnings hook up hose or whatever but the individual threads are a lot thicker.  You can actually stand on this braid and it won’t crush.  That isn’t really essential for this application though.  The other major part is this stainless plate:

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This goes over the braid like so:

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The plate has an interesting effect on the flow of the system.  It stops the weight of the grist resting on the braid itself – little bits of grain will flow and collect around the braid, but it isn’t crushed on there from above like it would be normally.   Even though it would appear to block access to a lot of the braid, I get much more consistent flow with the plate on there, and it never gets stuck even at high flow rates.  Another minor benefit is there is no longer that dead space of grain that never seems to lauter out properly at the bottom.  The bent corners of the plate are just big enough so the top of the plate rests slightly above the braid.

The other detail is the outlet tube.  I just have a normal fermenter tap, modified like so:

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There is a short slice of heavy duty silicon hose wrapped around a small section of 1/2″ copper pipe.  It just so happens that between the two, it forms a perfect wedged-in seal.  I put the silicon hose in first, leaving about 6mm sticking out the end.  Put a little keg lube on the copper pipe and stuff it all together.  It fits very snug and doesn’t leak air when the pump is sucking on the end.  I just use a wingnut hose clamp with HD silicon hose attached to the tap nozzle to feed to the pump.

Anyhow I like the fermenter mash tun because it is a good shape for one – tall means the wort is spread over a small area, helping with lautering efficiency.  Also it is lightweight compared to big stainless items – easy one handed lug to empty out the spent grain.  I can fit about 9-10kg of grain in here, so good for 40-50L brews.

Another advantage – when lautering, you can actually see the level of the liquid through the plastic as it drains below the grain bed.

I’m not saying it is the most awesome or bling-est mash tun out there, but I’m finding it pretty convenient.

Build your own cheap counter pressure bottle filler

Here is something you can build for hardly any cost which actually works much better than the usual three way valve T shaped one, for screw top bottles.

What you need:

  • A bottle lid
  • Some wood
  • Some keg line
  • Glue gun
  • 8mm Drill
  • Beer disconnect
  • Either a shut off valve or optionally a gas disconnect if you don’t have one.

Cut up the lid seal like so – some lids don’t need a seal, so you can skip this step:IMG_0379

This saves it from getting shredded when you drill holes in the lid like this

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Put the seal back in the lid. Cut your keg line into 2 1.5m lengths and slide them into the lid.
Make one tube longer so it protrudes out the bottom of the lid – this way it can reach the bottom of a bottle when it is attached. The other tube only has to go in about 10mm.

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Cut up your wood to make a frame with enough space to fit a 2L coke bottle.

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Drill a couple of 8mm holes to match the ones in the lid.

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Slide the tubes into the wood like so

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Next, get the glue gun and fill in the space between the lid and the wood – take care to get some between the tubes too. Then mush it all together while it is still hot. Add some extra around the sides for strength. I put some extra on the top along with a cable tie to keep the tubes together.

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Assemble the frame like so

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That’s pretty much it. Jam a beer disconnect on the longer tube, and put your valve or gas disconnect on the other one.

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How it is gonna work? Well the secret it that the lid itself is the relief valve. So this is how you fill bottles:

Attach the bottle.
Either open the gas valve to fill the bottle with CO2, or use a gas disconnect to steal gas from the keg. Put the gas supply back on the keg afterwards if you do it this way.
Turn off the gas
Plug the beer disconnect onto the keg – little or no beer will flow into the bottle yet.
Carefully unscrew the bottle from the lid – gas starts to leak out slowly and beer fills the bottle gently. There is actually a lot of adjustment range here, it works very well.
When the bottle is filled, remove the beer disconnect.
Unscrew the bottle and put the regular lid on. You’re done!
Check out the fill:

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I could have squeezed some more in there, it doesn’t foam up at all when filling.

The best part is this filler is hands-free while you’re filling, and doesn’t tip over all the time. Sanitation is easy with a spare keg filled with starsan or whatever. It is easy to set up and put away. I will be using it as my go-to filler now.

A solution for shorter keg lines

While being particularly violent while removing some taps from the door of a temporary keg fridge, I noticed the tendancy of the beer line to be rather ductile. This gave me the idea of using this property to make shorter keg lines, to turn this 6 metre run

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into this (1m original length)

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Turns out, it works pretty awesome. The benefits are less line used, less space in the fridge, and most importantly for me, less wastage when draining the stale beer from the keg lines – when you have 16 taps running, this adds up.

To make the thin tube, simply cut off a metre, step on one and and pull on the other hard enough to stretch it out. Try to grip it at the ends and do it in one hit – I think if the tube goes big-small-big-small-big it can’t be good. The stretched tube should have an ID of about 3mm. This 1m stretched length seems to be equivalent as far as dispensing goes to 6 or so metres of 5mm ID tube – I’m pretty sure the flow restriction math is rather non linear.

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You should get nice smooth transistions from big to small

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With this setup, the wastage amount from draining (to clear the old beer from the lines) is this much, instead of closer to 2/3 a glass.

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The pour is as neat as can be – I actually serve with more head than this usually

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I now run all my taps this way.