Infusion mash volume

[AzfromOz]

Howdy,

Am doing an India Session Lager with just under 3kg of grain, two infusion mash steps (67 degrees for 60 minutes, 74 for 10) and a batch sparge. Am using Beersmith for volume and heat calculations, and have had to tinker with the mash profiles to get one that matches what I want to do. I've come up with some volumes based on what Beersmith initially spat out but it's just guess work on my part so I wanted to check....

The closest mash profile is the single infusion, xx body, batch sparge, but that only gives me one mash step, telling me to use just under 8L of water and then two batch sparge steps with a total of 25L. When I add the second mash step Beersmith makes me estimate the water volume, so I subtracted 13L from the sparge and used that for the second step. My mash profile now reads (I rounded the volumes):

• 8L @ 77.8 degrees (mash in) for 60 minutes.
• 13L @ 79.9 degrees (mash in) for 10 minutes
• drain mash tun
• batch sparge with 12.5L.

So, my question is how do I know what volume to use for my second mash step? When I add the volume for the second mash step, Beersmith just subtracts that from the batch sparge, which is fair enough as it's trying to hit a kettle volume of 30L. I could put in three liters of near-boiling water or 20 liters of 78 degree water and both steps would hit my mash step temperature with either a huge or small sparge volume to follow. I've just guessed and taken Beersmith's recommended volume for the first batch sparge (it wanted me to batch sparge in two steps). Is there a rule of thumb for subsequent mash step volumes?

Cheers

Az

 

[MHB]

Ok without doing it all on paper, first up what sort of gravity are you expecting, given 3kg of grain into the kettle at 30L, assuming a 10% boil off leaving 27L at the end of the boil. just finger counting, 3kg of malt at best call it 76% potential (Coarse Grind As Is) and an 80% brewhouse efficiency 3*0.76*0.8=1.824kg of extract. looks like the OG would be about 1.026, pretty week beer, like 2.5%ABV.
Is this what you are aiming for?
Mark

 

[Jack of all biers]

After you have addressed what Mark reasonably brought to light. Here is the calculation I use. I think I stole it from Palmer or somewhere else, can't remember, but i converted it to metric and added some notes.
Funnily enough the example I made up is for 30L into the kettle, but the grain amount is different, so not that funny after all? :unsure:

Additional Liquor Temperature Equation:
Tw = {(T2 - T1)(0.41G + Wm)/Wa} + T2
Where:
Tw = The actual temperature (¡C) of the additional water (Liquor.)
Wa = The amount of water (liquor) added (in litres).
Wm = The total amount of water (liquor) already in the mash (in litres).
T1 = The initial temperature (¡C) of the mash.
T2 = The target temperature (¡C) of the mash.
G = The amount of grain in the mash (in kilograms).

For example lets say you want a 30L pre-boil volume from your 'No sparge' mash and we say we lose 1.3L per Kg of grain
T1=66C, T2=78C, G=5.1Kg, Wm=10.2L & Wa= 26.43L
Tw = {(78 – 66)(0.41x5.1 + 10.2) / 26.43} + 78 = 83.58C

So theoretically, in this case the 26.43L of liquor addition will need to be at a temp of 83.58C to bring the original Mash from 66C to 78C.

Notes:
1 - Wa=26.43L is because of the 6.63L absorbed by the grain (calculated at 1.3L/Kg). If you find you consistently lose more or less L/Kg to grain absorption, adjust your Wa additions appropriately.
2 - The calculations are mathematics and in real world conditions I would always up the Tw temp by 1-2C to make up for heat loss in transfer, stirring etc. So in the example I made above, I would round up my liquor addition to 85C. Even if the theoretical calculations were spot on, the additional 1.32C would only raise the final mash temp slightly (less than 1C).
3 - I have calculated a 2L/Kg Grain initial mash, so if you do a higher (or lower?) water:grain ratio, then adjust.

 

[AzfromOz]

Thanks guys for the responses.

@Jack of All Beers, I'm actually trying to solve for a reasonable volume of liquor to add, and I then let Beersmith do the temperature calculations. What I was trying to work out is what Wa in your equation should, be and I could work it out by fiddling with your equation (although it's literally been decades since I've done that!). As noted above, I can guess any volume and Beersmith will do the math. What I want to know is what is a reasonable volume. Now that I reread my post I realise I probably didn't make that clear.

Cheers

 

[Jack of all biers]

Sorry Az,

Yes, I scratched my head when I re-read your OP and what I posted, until I looked at my cheat sheet where I have saved handy calculations over the years. It was the calculation above the one I posted earlier. Sorry about that. I can save you from moving the other calculation about as I have already done that. Here's the volume one I think you are after.

Mash Infusion Equation:
Wa = (T2 - T1)(.41G + Wm)/(Tw - T2)
Where:
Wa = The amount of boiling water added (in litres).
Wm = The total amount of water in the mash (in litres).
T1 = The initial temperature (¡C) of the mash.
T2 = The target temperature (¡C) of the mash.
Tw = The actual temperature (¡C) of the infusion water.
G = The amount of grain in the mash (in kilograms).

The infusion water does not have to be boiling; a common choice is to use the sparge water at 77¡C. Then Tw becomes 77 ¡C and more water (Wa) will be needed to make up the additional quantity of heat.

For example T1=50C, T2=67C, G=5.1Kg, Wm=10.2L & Tw=95C
Wa = (67 – 50)(.41x5.1 + 10.2) / (95 - 67) = 7.46 Litres


Now you have both calculations .

A tip for young players. You don't have to waste time checking the temp of your boiling water once removed from the heat source before adding to your mash tun. General experience and observations of how quickly 100C drops to 95C, tells me to always calculate 'boiling' water additions as 95C even if you remove it from the boil and pour it straight into the mash tun within 5 seconds

EDIT - now it's hard to see, but that is 0.41 x G up there not 41 x G. I'd best change that on my own cheat sheet to save self confusion h34r:

 

[Jack of all biers]

Howdy,

Am doing an India Session Lager with just under 3kg of grain, two infusion mash steps (67 degrees for 60 minutes, 74 for 10) and a batch sparge. Am using Beersmith for volume and heat calculations, and have had to tinker with the mash profiles to get one that matches what I want to do. I've come up with some volumes based on what Beersmith initially spat out but it's just guess work on my part so I wanted to check....

The closest mash profile is the single infusion, xx body, batch sparge, but that only gives me one mash step, telling me to use just under 8L of water and then two batch sparge steps with a total of 25L. When I add the second mash step Beersmith makes me estimate the water volume, so I subtracted 13L from the sparge and used that for the second step. My mash profile now reads (I rounded the volumes):

• 8L @ 77.8 degrees (mash in) for 60 minutes.
• 13L @ 79.9 degrees (mash in) for 10 minutes
• drain mash tun
• batch sparge with 12.5L.

So, my question is how do I know what volume to use for my second mash step? (it wanted me to batch sparge in two steps).

Is there a rule of thumb for subsequent mash step volumes?

Cheers
Az

I'll answer your last question first. No there is no rule of thumb for volumes to add for mash step volumes. Some do no sparge and will up the volume to the total. You stated you wanted to do a batch sparge, so you will want to have roughly equal (give or take) volumes in each sparge. Given you want 30L pre-boil volume that's 15L* each. From your post I see you have nearly 3kg (without an exact figure from you I'll call it 3kg)

If I read your above post correct you add 8L @ 77.8C to your 3kg to get to your 67C. My calculations show your grains are -3.33C? (I double checked with Brewers friend which only goes to 0C grain temp, but still they had your 8L water temp at 77.3C for grain at 0C). This may be right if you store them in the freezer? but otherwise something doesn't add up.

But assuming I'm missing something about more grain or frozen grains. Once you have 8L and 3kg at 67C for 60 mins you will need to reduce the grain absorption from your total water to calculate your batch sparge. At 1.3L/Kg** = 3.9L so you have 4.1L from your initial 8L strike water.

To make up your 15L for your first batch sparge your will need to add 11.9L for your temp. Use my Additional Liquor Temperature Equation calc in my first post above to figure out the temp to get from 67C to 74C with 11.9 L = 78.95C

So in summary to get your 8L and 3kg @ 67C to 74C you will need 11.9L @ 79C. This in turn will give you a first sparge of 15L. You can then conduct a second batch sparge of 15L at 78C, or other temp as you will.

A word of caution though. These figures are mathematics and real world factors such as mash tun heat loss will effect the outcome. I always up the temps by a degree or so to make up for heat loss over time or inaccuracy in measurement etc...

* all water volumes are spoken of at 20C or V. To calculate higher temp volumes for accurate measurement V@80C = V x 1.03 or V@100C = V x 1.04
So therefore your 30L in the kettle when at 78C will show a volume of 30 x 1.03 = 30.9L (I'd round it to 31L to be sure)

** 1.3L/Kg absorption is fairly well spot on most of the time, but check your inputs and outputs for the first few brews and then every now and then to see if the grains/brand(s) you use are different than that (some grains have higher moisture content or are stored incorrectly which results in a higher moisture content)