Sanity Check with mash volume

Discussion in 'Homebrewing' started by Applecrew135, Nov 22, 2016.

Thread Status:
Not open for further replies.
  1. Applecrew135

    Applecrew135 Crusader (431) Jul 18, 2012 Pennsylvania

    I don't understand this...

    First time brewing a 5-gallon recipe and had an issue with mash volume calculations. My mash tun is a 5-gallon brew kettle. My Christmas Weizenbock calls for 12.25 lbs of grain:

    6.5 lbs Pale wheat
    3 lbs Munich
    1.5 lbs Maris Otter
    0.75 lbs Vienna
    0.5 lbs Crystal 120

    Based on Green Bay Rackers "Can I mash it" calculator, mash volume @ 1.25 qts per lb thickness calculated to 4.81 gallons, which is very close to my mash tun capacity of 5 gal (with no dead space).

    BrewCipher (and a later manual calculation) calculated a strike water volume of 3.83 gals. After accounting for the 0.32 gal / lb of grain, the numbers agreed with the "Can I mash it" calculator of 4.81 gal. I didn't really think too much about the strike water volume until I added three gallons into my tun. I looked at my sack of grains, looked at the remaining space in the tun... and thought "no freakin' way it's all going to fit".

    I doughed-in at 3-gallons, which brought the mash close to the top of the tun, and added another qt of water (total 3.25 gal) and decided that the remaining 1/2 gallon was simply not going to fit (1/2 gallon takes up 1" of space in my tun). I was already about 3/8 inch from the rim of the tun.

    So what gives? Why doesn't this calculation appear to work?
    Anyone else run into issues with the calculations? I'm pretty confident in the volume of my tun... but I may just measure it again to show I'm not going insane.
     
  2. VikeMan

    VikeMan Grand Pooh-Bah (3,067) Jul 12, 2009 Pennsylvania
    Pooh-Bah

    A few thoughts...
    - I've seen 5 gallons SS starter kit brew kettles that did not really have 5 gallons capacity. I think I still have one.
    - Were the grains and water fully mixed and had the water had a chance to saturate the grains? Or were there some unsaturated grains on top?
    - Did you weigh the grains yourself?
    - How did you measure the water?
     
  3. Applecrew135

    Applecrew135 Crusader (431) Jul 18, 2012 Pennsylvania

    Hmmm... some valid thoughts... most of these I think most people would assume (myself included) are correct, so good to challenge!

    At my LHBS, I watched as the person helping me weighed out the grains, and it was 12.25 lbs. Have to trust the scale was accurate, or they are giving it away.

    Grains were fully saturated

    I was using one-gallon jugs of bottled water (my well water tastes crappy) and the last 3 quarts were measured by hand,

    Leading culprit is assumed 5-gal volume of SS pot. I will confirm this first chance I get,

    Thanks!
     
  4. pweis909

    pweis909 Grand Pooh-Bah (3,250) Aug 13, 2005 Wisconsin
    Pooh-Bah

    Try dimensional analysis of your pot. 5 gallons = 18927 ml, or cubic centimeters.

    Volume of cylinder = pi * (radius)^2 * height
     
    hopfenunmaltz likes this.
  5. barleyhead

    barleyhead Devotee (329) Jun 5, 2008 New Jersey

    +1 for the dimensional analysis test. I've found that the advertised volume for a vessel doesn't necessarily match reality.

    I successfully used this hack for etching stainless steel kettles. Worked like a charm with professional looking results.

    http://hackaday.com/tag/brew-kettle/
     
    Hogue2112 and Applecrew135 like this.
  6. Brewday

    Brewday Zealot (721) Dec 25, 2015 New York

    You have to add in the volume grains will take up.
     
  7. Applecrew135

    Applecrew135 Crusader (431) Jul 18, 2012 Pennsylvania

    That's the question. The accepted wisdom is that a pound of saturated grain occupies a volume of 0.32 quarts. Grain volume should be 3.92 qts or 0.92 gal. Total volume should be 15.3125 qts (water) + 3.92 qts (saturated grain) = 4.81 gal, which is what calculators calculate.

    This overflowed my (assumed) 5-gallon tun, and it is appearing more than likely that my 5-gallon tun... ain't!

    I will measure it tonight and post the awful truth.
     
  8. Applecrew135

    Applecrew135 Crusader (431) Jul 18, 2012 Pennsylvania

    I've seen this before and it is cool! My new Bayou Classic kettle is already stamped with gradations... but to be honest, I don't believe the markings. They don't add up with measured volumes I've added in when testing boil-off rates with the new kettle.
     
  9. dmtaylor

    dmtaylor Savant (1,149) Dec 30, 2003 Wisconsin

    I have a 4-gallon kettle. Maybe you do too. They were standard way back in the day when I got mine in 1999. Those were the days of partial boils and topping up in the bucket. Fortunately for me, I brew small batches almost exclusively now (1.7-2 gallons) so it's perfect for me. But anyway.
     
  10. VikeMan

    VikeMan Grand Pooh-Bah (3,067) Jul 12, 2009 Pennsylvania
    Pooh-Bah

    I think those bottles are sometimes (often) overfilled. Don't know how much difference it would make, but just a thought.
     
  11. Applecrew135

    Applecrew135 Crusader (431) Jul 18, 2012 Pennsylvania

    The tale of the tape(measure)....

    After carefully measuring up my kettle and calculating the volume, I find that, much to my chagrin, it ain't no stinkin' 5-gallon kettle. Actual volume is approximately 4.7 gallons, which goes a long way in explaining my predicament. Dammit! Now I need a real mash tun that I can apply heat to for step mashing. I like my new Bayou Classic 8-gal kettle; may have to ask for another one for my birthday for a mash tun!

    Oh well... I guess this officially puts me on the path of building a RIMS system down the line
     
  12. VikeMan

    VikeMan Grand Pooh-Bah (3,067) Jul 12, 2009 Pennsylvania
    Pooh-Bah

    A triumph for the models! If you happen to mash something that should just barely fit into 4.7 gallon container, I'd be curious to hear if it does just barely fit. I can't honestly say I've field tested the assumptions in BrewCipher's mash tun overload warning calc that closely.
     
  13. Applecrew135

    Applecrew135 Crusader (431) Jul 18, 2012 Pennsylvania

    I'm actually relieved that the cause of my issue is an undersized kettle. I mean, if you can't trust a model, then you might as well be guessing. I'll certainly be keeping a closer watch on my mash volumes for a while and cross checking against BrewCipher and Can I Mash It.
     
    VikeMan likes this.
  14. GreenKrusty101

    GreenKrusty101 Initiate (0) Dec 4, 2008 Nevada

    For the sane: 5 gal batch = 10 gal mash tun and 8 gal kettle (probably 10 gal kettle if using propane)...imho
     
  15. barleyhead

    barleyhead Devotee (329) Jun 5, 2008 New Jersey

    I share your frustration. I bought a so-called 9 gallon kettle with two welds (for thermometer and drain valve). Actual capacity turned out to be 8.5 gallons according to the well known volume math.
     
Thread Status:
Not open for further replies.