170-250kg/m2 of dry milled grain is generally what I have seen suggested in literature and used by manufacturers. Higher adjunct ratios and difficult to lauter grist compositions will benefit from the lower end of the range. If I've done it correctly, calculating your lauter tun area based on 120" ID converts out to 7.25m2 and a suggested grist weight of ~1200-1800kg or ~2700-3900-lb based on the previous ranges.
Like Cullen has said, it is quite a wide range of grist sizes and would likely suit your mid-high sized grists well though nothing will be perfect. The lower end of the grist range only delivers about 60-70kg/m2, but if bed depths not foo far below the 12"/30cm recommended target then you may not have too much issue.
At the end of the day, product mix plays a role and if most of your volume is within an acceptable range of bed loadings, that may justify some of the tradeoffs seen at the extreme ends of the range.
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Wilson Hede
Jing-A Brewing
Beijing, China
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Original Message:
Sent: 10-17-2022 12:58
From: Michael Smith
Subject: Mash tun sizing
We have a lead on a lauter tun that just may be too large for our ideal operation.
does anyone have information regarding the ideal grain bed depth / proper sizing techniques?
for reference we are looking at our largest mashes being 2800-lbs and our smallest being 990-lb
this particular tun is 120" I.D.
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Michael Smith
Head Brewer
Eel River Brewing Co.
Fortuna, CA
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