Grain Absorption

[Sloth]

Hey all,

Im in the process of a detailed design for my AG setup and I have come across some inconsist values.
Promash has given a grain absorption rate of 1.01L/kg but John Palmers Book has 1quat/pound (works out to 2.1L/kg).

Can AGers out there give me there estimates on grain absorption rates??

Also, for a specified batch size what is the total amount of water in your HLT, including dough in and sparge. I am aware this depends on a lot of factors but i am jsut after a general range.

Cheers, Sloth.

 

[DJR]

I just use 1.1L per kg... works fine for me

 

[Benno-5]

i did my first ag last weekend as was 5 litres short in the end, thatt might be because i only allowed 1lt per kg. If the palmers book is correct this would be my problem. hmmm

 

[Sloth]

i did my first ag last weekend as was 5 litres short in the end, thatt might be because i only allowed 1lt per kg. If the palmers book is correct this would be my problem. hmmm

Hence my reason for needing to know

I am currently working with the 2.1L/kg from Palmer which means for 20L in the keg, total water needed is a touch under 46L. I beleive my calculation to be correct. Can somebody confirm if this amount looks about correct?

Cheers, Sloth.

 

[Benno-5]

I used 34 so if i was to add an additional 5 it would be a total of 39. But that is my system and its by far sorted out yet.

From what ive been told its probably best to have more water in the hlt that less. Sparge until the runnings from the mash become clear then stop. Thats how much water you need. Someone tell me if im wrong here?

 

[Peter Wadey]

Sloth,
With a handle like that, it's sounds like experimentation would be just too much effort, but that is what I recommend. Crush & mash/ hydrate a small volume and measure the retention.

FWIW I use 1.2l/kg, but I strongly advise experimentaton with your own crush.

Peter

 

[Screwtop]

I used 34 so if i was to add an additional 5 it would be a total of 39. But that is my system and its by far sorted out yet.

From what ive been told its probably best to have more water in the hlt that less. Sparge until the runnings from the mash become clear then stop. Thats how much water you need. Someone tell me if im wrong here?

I use 1.1L/Kg Beersmith uses 1.0025 so I add the additional to the HLT deadspace amount. Test runnings when you are near kettle pre boil volume, don't continue sparging lower than SG 1.010 as a rule of thumb.

 

[Sloth]

Thanks for the feedback guys. Sounds like some experimentation may be the go!

Sorry I didn't repy sooner. Been pretty busy.

Cheers, Sloth.

 

[MHB]

A good rule of thumb is:-

For every 1 Kg of grist you need 7 litres of water to makes 6 Litres of sweet water with 1 litre retained in the grain.

Naturally if you are going to dough in thin you will need less for sparging and visa versa.
Best to over design a bit to give your self some flexibility, a range from say dough in at 2:1 to 4:1 should tell you what size HLT to build; and will allow you to try a range of options until you find the one that works best for you.

MHB

 

[Cortez The Killer]

Sorry to bring up an old thread...It's just that I've got some questions that've been playing with my mind since Sunday when I did my second AG.

Now this is what happend (I batch sparge)

+ 17.4 L = mash in @ 3 litres / kilo (3 x 5.8kg)
+ 18.0 L = sparge
= 35.4 L
- 5.8 L = Less loss to grain
= 29.6 = expected volume in kettle

However volume in the kettle was somewhere between 32.5 - 33 L

Lets say that this was inflated by 4% due to being warm ie 29.6 * 1.04 = 30.8 L

I boiled the kettle very vigourously and after cooling (no chill) and losses to kettle I ended up with 26 L in the fermentor - I had figured on 23L

note I didn't have much loss to the kettle (maybe 250ml) because of my new pickup tube and using a jumbo hop bag from Ross

I've figured that I hit 80% efficiency again

This was the grain bill
9.4 0.60 kg. Cane Sugar Generic 1.046
6.3 0.40 kg. Wheat, Torrified US 1.036
76.6 4.90 kg. IMC Ale Malt Australia 1.038
6.2 0.40 kg. Black Patent Malt Great Britain 1.025
1.6 0.10 kg. Chocolate Malt Great Britain 1.034

Now these are my questions

Is it possible that grain absorption is much less that 1 L per Kilo? Do certain grains / crushes give up more water than others.

Should I stop sparging when I have the desired volume in the kettle instead of drawing out low gravity wort at the end?

Or is it likely that my measurements were just out (I did do them fairly carefully - but I do intend to recalibrate my dip sticks to ensure that they are accurate)?

Cheers

 

[lonte]

Should I stop sparging when I have the desired volume in the kettle instead of drawing out low gravity wort at the end?

Yes.

 

[Screwtop]

Yes.

But I don't suspect your runnings were anywhere near low, looks like a 60 min boil to result in that post boil volume, did you hit your target OG?

Also I only see 5Kg of malted grain in your grain bill.

 

[Cortez The Killer]

I did my calcs based on an efficiency of 75% and aimed for an OG of 1.065 at 23L

I ended up adding a further 200g of sucrose toward the end of the boil to bump up the gravity - to bring it to 600g

In the end I ended up with and OG of 1.064 but with 26L into the fermentor - I make that out to be about 79-80% with the sucrose addition

I'm gonna have to check my dip sticks - because something doesn't add up

I'm not sure what you mean by only 5kg - why do you exclude the wheat + black?

Cheers

But I don't suspect your runnings were anywhere near low, looks like a 60 min boil to result in that post boil volume, did you hit your target OG?

Also I only see 5Kg of malted grain in your grain bill.

 

[DJR]

I'd suspect the following questions need to be answered

1. Was your preboil volume accurate, how are you measuring it (check your dip sticks)
2. Was the amount of water added accurate
3. What type of burner are you using and i assume you got a nice rolling boil going
4. What was the sparge water temperature

One thing to watch out for with dip sticks is the thickness of the kettle base, it often is alot thicker than the sides.

But i can't imagine you suddenly getting a 0.5L per kg of grain absorption figure. 0.9 or 1 i could expect but 0.5 is WAY too low. Next time use a little less sparge water or boil more off. Getting around 80% on your 2nd AG is good stuff though.

 

[Cortez The Killer]

1. Was your preboil volume accurate, how are you measuring it (check your dip sticks)

I think the issue may be here - I'll go away and re measure everything

2. Was the amount of water added accurate

As above - I pretty sure it was

3. What type of burner are you using and i assume you got a nice rolling boil going

Nasa - very nice boil

4. What was the sparge water temperature

76-78*C


I'll re measure everything - and have a go at my 3rd AG and report back

Thanks for the help, my mind is a little more at ease.

Cheers

 

[crozdog]

Instead of calibrating your dipstick by pouring "known" volumes into your kettle, try this bit of maths trickery (assuming that you have a circular kettle):

1. calculate the radius in cm (measure the diameter & divide by 2)
2. Dig out the calculator & use the old pirsquared formula (ie 22/7 x radius x radius)
3. You now know the volume (in ml) per 1 cm of height!!!

You can then mark off a dipstick, or do what I do, & use a steel rule instead.

I made up a spreadsheet & printed it out so I can easily lookup volume & height. When I want to drain a certain amount from the hlt (eg to mash in or sparge) I simply look up the sheet for the required volume, and put the ruler the required distance (height) down from the water line & clamp it there with a bulldog clip, then turn the tap on. When the water level drops to the bottom of the ruler, I know I have measured out the required volume. Quick, easy, simple & repeatable. it works great for underletting ;-)

let me know if you don't understand or want more info.

Beers

Crozdog

 

[therook]

crozdog,

how would you use this formula with a converted keg ( Not a flat bottom )

rook

 

[Cortez The Killer]

I use a 25 L pot with a ruler as the dip stick for my HLT

And I use a converted keg as my kettle for which I've made a really big ruler with markings from a length of aluminium

Because i've inverted the base I basically stand the ruler in the middle of the kettle and take readings.

I've got the excel charts drawn up as well.

Neither HLT or kettle are perfect cylinders - so I can't use maths - I did think about it though

Cheers