BeerSmith Fly Sparge Volume Calculation

Hey

Does anyone know how BS does the fly sparge volume calculation?  I know it's based on achieving the brew length required (e.g. 19L), but accounting the losses and evaporation in the boil and the water already used in mashing.  I can't get the numbers to add up; BS always comes out with more sparge water, presumably because of some assumption on residual water in the grain/mash tun.  Anyone know what that assumption is?

Thanks

John

BeerSmith figures water needed by taking the desired volume into the fermentor and then adding in all the losses which are defined in the equipment profile and the calculation for water absorption in the grain and the calculated boil-off. 

so the equations look something like this:

Total water = Batch volume + loss to trub and chiller + boil off rate * time of boil + Grain wt * Grain absorption rate + Lauter tun dead space.

Water for mash = Total water - Top up Water for Kettle - Top up Water for Fermentor

Sparge water = Water for mash - infusion water for mash

Water for mash infusion and sparging are always given at temperature, so the values cited on the mash page have the thermal expansion figured into them.

Thanks for the reply. So I think it's the grain absorption that's alluding me. Is this hard coded into BS or user/grist defined?

You can set the grain absorption value in 'options' >> 'advanced' > 'Grain Absorption'

Unless you have measured your grain absorption and have confidence in what the value should be, you may want to be careful about changing this value.

Oginme said:

BeerSmith figures water needed by taking the desired volume into the fermentor and then adding in all the losses which are defined in the equipment profile and the calculation for water absorption in the grain and the calculated boil-off. 

so the equations look something like this:

Total water = Batch volume + loss to trub and chiller + boil off rate * time of boil + Grain wt * Grain absorption rate + Lauter tun dead space.

Water for mash = Total water - Top up Water for Kettle - Top up Water for Fermentor

Sparge water = Water for mash - infusion water for mash

Water for mash infusion and sparging are always given at temperature, so the values cited on the mash page have the thermal expansion figured into them.

Click to expand...

Like John, I found that BS seems to display more sparge water than necessary, and I even have a theory.

My understanding is that during the mash most of the starch is converted into sugar, and this dissolved sugar does increase the initial water volume.  Apparently, BeerSmith doesn't take this additional volume into account.

For example 6 kg of malt, with 82% Maximum Yield and an extraction efficiency of 85% should add about 4.2 Kg  extract to the mash. This dissolved extract should rise the mash volume of about  0.62*4.2 = 2.6 liters.

The 0.62 "displacement" factor is related to the addition of 100% sugar  to water. It means that if you add 1 Kg of pure sugar to your mash water, you should get a volume rise of (about) 0.62 liters.

So, given the way in which BS calculates volumes, I expect  the sparge water volume shown by the program to be in excess of 2.6 liters (in the example above)

I may be wrong, but please show me why  :-\

      Alessandro

The volume displacement for the extracted sugars, proteins and fats from the grains is incorporated in the value for grain absorption. 

When you have your process correctly entered into BeerSmith, you will find that your water volumes balance extremely well.