False Bottoms for 50l Kegs Under Development

[punkin]

Hi all, due to a number of customer requests we will soon be releasing a very good keg conversion kit that will allow people to turn a 50l keg, or indeed any other weldable vessel, into a conical fermenter.

The bit we still have to design and build is a filter disc/false bottom section. This will be approx 8"diameter to fit an 8"ferrule.

We currently have acid etched filter disc in 2-4"sizes that are made with a fine screen of holes for other purposes, mainly carbon filtering..



What we'd like to do would be to have a screen that would double as a false bottom, but still be fine enough (ie 1.5mm minimum siz holes) to use as a filter screen.

What i suspect we will be doing though is producing either a slotted false bottom and having people use a cloth filter on top of that or producing a separate filter screen.

What we need help with as being ignorant to the science of brewing if not the enjoyment of it, is the design of the perfect false bottom. :drinks:

We think we know it should be slotted, we don't know what % of the surface area those slots should take up (we think it may be 30%, but 50% has been thrown up too).
We don't know how wide or how long those slots should be. :huh:

We're hoping this product will be a quiet step forward for home brewers to be able to kit themselves out with some very nice bling for an affordable price and any help we can get to making this right for you guys will be appreciated.

 

[Aydos]

What's your website?

 

[Logman]

What I've always wondered is why the center of a false bottom is perforated (say, the inner 8 inches or so). It would make false bottoms far more useable in kettles instead of whirlpooling (I use a falsie atm in my kettle). I've considered attaching a SS disc to my falsie to catch the inner trub that falls directly around the outlet.

 

[punkin]

Website in my sig, forum can be found linked on my site.

This FB will be 8" diameter only. We are thinking more towards conicals than boil kettles. It needs to fit an 8"ferrule, with the conical below that. A lot of our customers are fermenting on the grain. The FB will be for those. It will sit above the cone allowing fruit and grain washes to be drained leaving the trub behind. Good for winemakers too.

The conical kit will be available without the FB for those who don't need it. IE those doing beers only.

 

[punkin]

What we're really looking for here is design advice so we bring to you guys the best possible product. We need to know the questions in the first post.

Looking for technical input based on knowledge or experience as to the size and shape of the slots, or indeed holes if there is no real benefit to slots.

If someone can point to some references that would be great too, we're not too lazy to do research, just don't know where to start if not with the actual users.

The end use would equate to a mash tun much more than it would a boil kettle.

 

[mash head]

Palmers book has a whole section devoted to lauter tun design and fluid dynamics, might be what you are after.I think the max amount you can drain through without compacting the grain bed too much would be ideal, your surface area is pre determined so hole size and number is all you can work with. I recently bought some perf, stainless for a new take on BIAB and the holes size/centres were limited. I went for small holes (I think under 2mm)and lots of them but I have surface area on my side. I would deffinately check out the book above as he gets right into it.

 

[punkin]

Thanks mate, i'll search it up.

By the way for those who may be tempted to chime in, some of the worts we are talking about here for my other customers have high adjunct %'s (up to 100% in some cases).

For you guys that wouldn't matter too much though.

 

[wessmith]

Brewing practice does vary in preferences for the % open area in lauter plates. Traditional German style equipment will be around 12% with English ale single infusion systems closer to 25%. We go with slotted plates in our equipment at 18% but we have used wedgewire (or V-wire) plates at around 25%. Higher % open areas require a coarser malt crush and there can also be problems with too faster runoff. I would suggest you investigate the wedgewire option as you can vary the wire/gap dimensions to achieve the required open area. Try Johnson Screens -

http://www.johnsonscreens.com/content/maltingbrewing

Wes

 

[MastersBrewery]

Brewing practice does vary in preferences for the % open area in lauter plates. Traditional German style equipment will be around 12% with English ale single infusion systems closer to 25%. We go with slotted plates in our equipment at 18% but we have used wedgewire (or V-wire) plates at around 25%. Higher % open areas require a coarser malt crush and there can also be problems with too faster runoff. I would suggest you investigate the wedgewire option as you can vary the wire/gap dimensions to achieve the required open area. Try Johnson Screens -

http://www.johnsonscreens.com/content/maltingbrewing

Wes

The rotary sieves and screens in the link had me wondering if a recirc mash tun would work in that configuration rims or herms

 

[punkin]

Had a look through how to brew and all the stuff i read when designing my mash tun was there, but could find no information on slot sizes or hole diameter, back to google i guess.

 

[wessmith]

Punkin, sorry but I thought you were mainly interested in the material to use. Most slotted lauter plates are in the 0.6 to 0.8mm region. I would not go above 0.8mm with this type of plate but calculate your gap to spacer dimension to yield around 18 to 25% open area. With drilled holes or perforated plates a maximum of 1.5mm is good. Again dont go above 1.5mm as the holes will block very easily. Those plastic false bottoms that used to be around (I still have one somewhere I think) had 3/32" holes on a 5/32 pitch (thats 2.4mm and 4.0mm) and a 35% open area. You needed a very course crush to be able to set the filter bed and then the runoff was just too quick. For a number of years I used a perforated stainless steel plate with 1.0mm holes on a 2.0mm pitch. I worked quite well, had an open area of 28% or so but was only 0.75mm thick and required multiple support points to take the grist load (I used inverted 6mm cap screws) but the nuts were above the plate and were a real pain when removing the spent grist.

Wes

 

[punkin]

Thanks Wes, that's exactly the type of info i've been after. Did a little googling around today and saw that most of the popular hole drilled ones used 1.5mm holes. Just gota figure now whether holes are better than slots and if not then slot dimensions. We can get pretty much anything acid etched fairly simply and very cheaply. Can't go below thickness of the material in hole size though.

 

[punkin]

This fitting should give people an idea of what we will be releasing. It started as a suggestion from one of our customers and i mocked it up using parts i had in stock like this...





Then we had it produced, this prototype is with 3/4 inch ferrules on the bottom and side branch, we will be producing them in 2" as well, not sure which size would be more popular though, we will probably drop one....






This could be attached to a keg with an 8"ferrule welded to the bottom of the keg. That would give you a 2"ferrule (standard neck) on top of the keg to attach a endcap with blow off or airlock. All attachments would be triclamp.


Any interest now?

 

[djar007]

I will take one. That is awesome. Be watching for the first batch. Great work punkin. These are sure to sell like hotcakes.

 

[Dan Pratt]

do you have a complete 50lt keg assembly with this conical base pictured for us to see?

 

[MastersBrewery]

The sanitary weld to the bottom of the keg could be a challenge though probably the cheapest 50l ss fermenter going

 

[punkin]

I will be offering this as a kit or as single parts, not with the welds done. I will be shortly stocking high quality new Franke kegs, but don't expect this will be a money saving deal if you were to buy a new keg from me, pay the freight and the welding. You'd be getting up to the value of a basic purpose built conical.
But for those who have a spare keg in the shed and a mate who can TIG, this will represent outstanding value as a budget fermenter.
As stated, some will demand sanitary welds, where some will be happy with thourough cleaning and sanitising. I'm not prepared to stake my name on someone elses welds. It's not my core business.

It would be up to the customer to source a keg according to how they feel about that and to search out a fabrication shop or a mate to do the welding.

It has been raised with me in PM too that there could be an issue with yeast and trub sitting on the lip at the bottom of the keg and not sliding into the reducer, this won't be an issue for the users it was designed for, but it may well be an issue for those who are going to drink the beer that comes out of it. Just so you are aware.
The good bit is that with the filter screen i believe you could add either loose pellets and definately be able to add flowers and not worry about hops in your beer.

edit;
This is what an 8" ferrule looks like on a keg, this was built as a pressure cooker when i was doing a lot of mycology..