Seeking Advice on Building a False Bottom

[Lenny]

I'm in the process of converting a 400 gallon single wall ss tank into a mashtun. In terms of screen material to fabricate a false bottom from, I've been looking at some perforated stainless sheets from McNichols (http://www.mcnichols.com) — specifically, this stuff (image below)...

McNICHOLS_R Quality Perforated Metal, Round Hole, Stainless Steel Type 304, 16 Gauge, Mill Finish, 3/32" Holes on 5/32" Centers, Staggered Pattern, 33% Open Area, Sheet, 36.0000" Width x 96.0000" Length

Item#: 1833531638

TOTAL*: $274.08

I figured I'd have a local/reputable metal guy cut the sheet into 2 half circles and weld on some support braces and legs. Would this screen be appropriate enough for lautering a mash of barley/wheat/rye and the like? I'm feeling like something thicker than 1/16 (16 gauge) would be better but I'm not seeing much else out there. Is there anything else that might be recommended by others who've already done this sort of thing?

[Monster Mash]

What you described should work fine. I would leave an inch or more below it making sure you clear the valve. You can get a real even mash if you mash in from below. Make sure you have pleanty of support since kinda thin. Cheers

[PeteB]

An excellent product is stainless WEDGE WIRE mesh.

It consists of thin parallel slats that are almost triangular in section. The gap at the bottom is wider than the gap at the top which prevents particles getting stuck half way through the slot.

The slats need to be about 1mm apart.

The sheets are reasonably rigid so they don't need as much support as the perforated sheets I have seen.

[Ned]

The perforated sheets will absolutely work but I think you'd be better off going with something like what PeteB is talking about. I've used those same sheets before and the holes are the perfect size to fit a piece of barley ALMOST all the way through so you'll have some clogging, clean up will be a bit of a pain and at 1/16" you'll need a lot of support underneath. With a 400 gallon tank I imagine you'll hop in to shovel it out and those sheets won't last long with a person walking around on them. The wedge wire is stronger, less prone to clogging, easier to clean, and tough.

[Rich Morgan]

The general rule is the holes (if they are circular rather than slots) should be 2 to 2.5 times larger than the average grain particle (when fully sparged, ie swollen) Sure some will pass through initially, but its the bed of grains that provides the filter medium, if the holes in the plate are too small you will get blockages and flooding. Strongly suggest you trial the chosen size first.

rich..

[Rich Morgan]

The general rule is the holes (if they are circular rather than slots) should be 2 to 2.5 times larger than the average grain particle (when fully sparged, ie swollen) Sure some will pass through initially, but its the bed of grains that provides the filter medium, if the holes in the plate are too small you will get blockages and flooding. Strongly suggest you trial the chosen size first.

rich..

I should also add, that circular punched plates are not ideal for false bottoms, woven wire mesh is far superior, or slats as described by another member. Wire mesh will need support members, the grain bed gets very heavy.

[Denver Distiller]

IMHO, if you are an all-malt distillery, or that's where the majority of your work will be, lauter plates is where the majority of your capital outlay should be. A 10% gain in lauter efficiency will pay for itself in a hurry. We had laser cut plates made for our brewery, and the capital outlay was paid in full inside of a year.

Food for thought.

[Lenny]

Thank you for the replies. Can't believe how much i'm deliberating over a stupid piece of screen!

I've been trying to dig up some information on efficiency comparisons between various lauter mediums but haven't found much. I get that the 3/32" holes in the perforated sheet (as pictured in my first post) would likely be more difficult to clean and less structurally sound than this wedge or v wire. I'm not terribly concerned about the weight impact of standing on it since we'll be shoveling grains out through a manway, but if there's a better performing material out there I'd certainly like to weigh out all options.

It's sounding like a custom engineered solution, along the lines of what Denver Distiller had mentioned using, would be the ultimate in efficiency (kinda curious what the nature of the laser cut screens were that make them more ideal than other options - interesting stuff). Here's where I'm finding myself a bit stumped though: I could live with the perforated steel sheet as a false bottom figuring that it will be beefed up with some cross members for support so long as it would offer up acceptable efficiency at around 85-90%, and flow without propensity to clog or get stuck so long as proper mashing/lautering practices are followed -BUT- if a wedge wire material or even the slotted steel sheet might be known as a given to offer up significantly higher efficiency... we'll, I can find a way to part with the extra $'s for that material.

It's looking like a wedgewire false bottom would run me around $2,000 all said and done. I know that's chump change in the scheme of things but I'm trying to keep it tight wherever I can. I'm viewing this MLT build as something that I will likely scale up from in the next few years. So after the additional research I've done with the information offered up by you all (thanks again), I guess what I'm looking for insight on is — can I pull off decently high efficiency with reliable performance using the perforated steel as pictured above without kicking myself in the ass for trying to save $1,500 over the cost of a material that *might* make things perform at a higher standard and give me a 10% jump in efficiency?

[Made in Maine]

I'm in the process of converting a 400 gallon single wall ss tank into a mashtun. In terms of screen material to fabricate a false bottom from, I've been looking at some perforated stainless sheets from McNichols (http://www.mcnichols.com) — specifically, this stuff (image below)...

McNICHOLS_R Quality Perforated Metal, Round Hole, Stainless Steel Type 304, 16 Gauge, Mill Finish, 3/32" Holes on 5/32" Centers, Staggered Pattern, 33% Open Area, Sheet, 36.0000" Width x 96.0000" Length

Item#: 1833531638

TOTAL*: $274.08

I figured I'd have a local/reputable metal guy cut the sheet into 2 half circles and weld on some support braces and legs. Would this screen be appropriate enough for lautering a mash of barley/wheat/rye and the like? I'm feeling like something thicker than 1/16 (16 gauge) would be better but I'm not seeing much else out there. Is there anything else that might be recommended by others who've already done this sort of thing?

Lenny,

The mesh is sized well. I built one for a brewer and this was the very sheet that was used. There was an angle iron(stainless) that was built to hold the space off the bottom and support the mesh. stainless rivots held the mesh to the frame. this makes it relatively painless to change the mesh if desired. The Brewery where this lives is very happy. and yes, She was working with a tight budget. She also has a manway door for cleanout. each half fits through the door. you may not have that option with a larger tank. you could go with a three part.

Jesse