Sparge Time vs. Amount of Grain

[philm63]

Does the size of the grain bill determine the recommended sparge time? Over the last two batches, Kolsch and IPA, I noticed a difference in the amount of sugars left in the MLT after reaching my BK volume. The Kolsch had final runnings out of the MLT of 1.009 SG and the IPA was 1.016 SG. Each sparge was right around 40 minutes (fly sparge) at 170 F. (5-gallon batch size, electric HERMS). Sparge methods were identical between the two batches.

I don’t necessarily feel like I need to troubleshoot this issue, rather I’d just like to better understand the relationship between the amount of grain in the MLT and the time taken to sparge to a consistent point; say 1.010 SG for example. Is this something that can be adjusted for in Beersmith?

Perhaps an equipment profile could/should be created for different styles to account for slightly different volumes in the MLT? Begs the question; is there a significant difference in efficiency between large and small grain bills? Should my efficiency in my equipment profiles be lower for higher gravity brews? (Kolsch – eff. = 82%; IPA – eff. = 80%, for example)

 

[Vale71]

Should my efficiency in my equipment profiles be lower for higher gravity brews? (Kolsch – eff. = 82%; IPA – eff. = 80%, for example)

In short, yes, most definitely. Sparge rate should be constant for a given equipment, therefore it should increase or decrease only based on the amount of sparge water.

 

[doug293cz]

The chart below is for batch sparge, but if you are doing a really good job of fly sparging, your lauter efficiency should be about 2% - 3% above the top (green) solid line. Mash Efficiency equals Conversion Efficiency times Lauter Efficiency. Your conversion efficiency should be pretty constant with grain bill size. You can determine your conversion efficiency using the method here. Use your brewing software to calculate mash efficiency, and then calculate lauter efficiency as:

Lauter Efficiency = Mash Efficiency / Conversion Efficiency
​

If your lauter efficiency isn't above the solid orange line, then you are wasting your time by fly sparging, and could to better by batch sparging.

Brew on

 

[Tom R]

I'm trying to follow along, I have the same (or similar) question:

When I doubled my batch size from 14 lbs of grain to 28 lbs, should I have increased my fly sparging time from my usual 45 minutes?

I didn't...And maybe that's why I've been a few points low on the OG lately? Could've been a baziliion others factors too, I guess...

 

[FunkedOut]

The flow rate on the sparge should remain the same to achieve the same effeciency.
If you sparge twice as much water in the same amount of time, you doubled your flow rate, lowering your effeciency.

 

[Tom R]

Ah, that makes sense. Thanks!

I don't brew in any hurry at all, I enjoy the process and make no other plans that would interfere with a 6 hour session. Looks like I'm going to plan on almost 7 hours for the next batch. Good times!

 

[Robert65]

Common misconception, but flow rate is a red herring. It's not about flow rate, it's about velocity. For any system, there is an optimal velocity, based on loading, to achieve optimal extraction without compacting the grain bed. Dave Miller gave a very good if brief introduction: http://brewlikeapro.net/lautering.html

 

[TheMadKing]

Common misconception, but flow rate is a red herring. It's not about flow rate, it's about velocity. For any system, there is an optimal velocity, based on loading, to achieve optimal extraction without compacting the grain bed. Dave Miller gave a very good if brief introduction: http://brewlikeapro.net/lautering.html

And just to clarify this statement because I had to sit and think about it for a second:

The difference between flow rate and velocity is the diameter of the piping. 2gpm through a 4" diameter pipe has a very low velocity and 2gpm through a 3/16 diameter pipe has very high velocity and that's what is really going to cause the channeling that drops your efficiency.

Great post Robert, thanks!

 

[Vale71]

Common misconception, but flow rate is a red herring. It's not about flow rate, it's about velocity. For any system, there is an optimal velocity, based on loading, to achieve optimal extraction without compacting the grain bed. Dave Miller gave a very good if brief introduction: http://brewlikeapro.net/lautering.html

For a given system, flow rate and velocity are directly correlated (the tun is not going to expand or contract as you change the valve position) so not really a red herring, just a different way to quantify something. With the advantage that it's relatively simple to instrumentally measure flow rate, but rather expensive to measure actual flow velocity.

 

[TheMadKing]

For a given system, flow rate and velocity are directly correlated (the tun is not going to expand or contract as you change the valve position) so not really a red herring, just a different way to quantify something. With the advantage that it's relatively simple to instrumentally measure flow rate, but rather expensive to measure actual flow velocity.

What about velocity of the input and outputs to the system in a recirculating mash? Those could be altered by using larger diameter fittings, etc, so it's still a valid consideration isn't it?

or would that even matter?

I guess input velocity matters only if your inlet is spraying directly onto your grainbed, and outlet velocity won't matter because it doesn't affect the velocity through the grainbed

 

[sicktght311]

Aside from all this talk about Sparge rates, its common experience that the higher OG/Grain bill you go, the more your efficiency is going to suffer since you're trying to move the same amount of water through a larger grain bill, resulting in more sugars left behind.

Common practice is to sparge longer, with more water, and then boil longer to reduce down to your target size, thereby capturing more of the sugars and making a more concentrated wort.

Without doing the above, you can easily see efficiencies drop by 20%

 

[TheMadKing]

Aside from all this talk about Sparge rates, its common experience that the higher OG/Grain bill you go, the more your efficiency is going to suffer since you're trying to move the same amount of water through a larger grain bill, resulting in more sugars left behind.

Common practice is to sparge longer, with more water, and then boil longer to reduce down to your target size, thereby capturing more of the sugars and making a more concentrated wort.

Without doing the above, you can easily see efficiencies drop by 20%

Yep, spot on. Other things that may help are:

-mash longer than usual (2 hours instead of 1)
-frequently stir the mash (every 10-15 mins), or recirculate (I've even found that stopping recirculation midway through the mash, stirring, letting the grainbed settle and restarting the recirculation boosts efficiency somewhat)
-batch sparge and allow the sparge water to sit for 10-15 minutes before running off and stir thoroughly
-batch sparge multiple times as Doug pointed out above

 

[Vale71]

What about velocity of the input and outputs to the system in a recirculating mash? Those could be altered by using larger diameter fittings, etc, so it's still a valid consideration isn't it?

or would that even matter?

I guess input velocity matters only if your inlet is spraying directly onto your grainbed, and outlet velocity won't matter because it doesn't affect the velocity through the grainbed

The velocity being discussed here is only the velocity through the grain bed.

 

[TheMadKing]

The velocity being discussed here is only the velocity through the grain bed.

I realize that's what you were referring too and your point is a good one. However since this thread is about lauter efficiency, in my post (which I edited and apologies if it wasn't clear), wouldn't input velocity have an effect on efficiency if it causes channelling or buried the sparge inlet below the grain bed?

 

[doug293cz]

Aside from all this talk about Sparge rates, its common experience that the higher OG/Grain bill you go, the more your efficiency is going to suffer since you're trying to move the same amount of water through a larger grain bill, resulting in more sugars left behind.

Common practice is to sparge longer, with more water, and then boil longer to reduce down to your target size, thereby capturing more of the sugars and making a more concentrated wort.

Without doing the above, you can easily see efficiencies drop by 20%

This effect is quantified in the chart I posted above. The horizontal axis is the ratio of grain bill weight to pre-boil volume. This means that a 12 lb grain bill with a 6.5 gal pre-boil volume has the same efficiency as a 24 lb grain bill with a 13 gal pre-boil volume. If you boil both with the same boil off rate, you have to boil the larger batch twice as long to get rid of the excess water (assuming you want a post-boil volume ratio of 2, say 5.5 and 11 gal.) If you don't use the extra water in your double batch, the efficiency will go down.

Things get even worse if you want to make a big beer, say 18 lb of grain for your 5.5 gal post-boil volume. Now instead of 6.5 gal pre-boil, you will need 9.75 gal pre-boil to maintain the same lauter efficiency as the smaller beer. At a 1 gal/hr boil off rate, you'd have to boil more than 4 hrs to lose 4.25 gal rather than 1 gal during the boil.

Brew on

 

[doug293cz]

Yep, spot on. Other things that may help are:

-mash longer than usual (2 hours instead of 1)

This will improve your conversion efficiency if, and only if, your conversion was not already at 100%. Won't have any effect on lauter efficiency.​

-frequently stir the mash (every 10-15 mins), or recirculate (I've even found that stopping recirculation midway through the mash, stirring, letting the grainbed
settle and restarting the recirculation boosts efficiency somewhat)

Again, this can improve conversion efficiency, if you aren't already at 100%. Also no effect on lauter efficiency.​

-batch sparge and allow the sparge water to sit for 10-15 minutes before running off and stir thoroughly

If you are at 100% conversion efficiency, then stirring until the wort is totally homogenized is all that is needed, and the wait time will do nothing. If you stirred insufficiently, then the wait time will allow diffusion to get you more wort homogenization than the inadequate stir did, thus improving lauter efficiency. If you aren't at 100% conversion efficiency, and you didn't mash out, then waiting after adding sparge water can allow more conversion to occur, thus improving conversion efficiency.​

-batch sparge multiple times as Doug pointed out above

Brew on

 

[FunkedOut]

I realize that's what you were referring too and your point is a good one. However since this thread is about lauter efficiency, in my post (which I edited and apologies if it wasn't clear), wouldn't input velocity have an effect on efficiency if it causes channelling or buried the sparge inlet below the grain bed?

Burying the sparge inlet below the grain bed is not ideal.
That aside, as long as you maintain some water above the grain bed, and your input to the lauter tun is delicate enough to not disturb the grain bed, then the velocity of the sparge supply in its tubing is irrelevant.
The sparge supply simply feeds the water that covers the grain bed.

The velocity that matters is through the grain bed.

If you rather specify velocity rather than flow rate, think of the lauter tun diameter as your pipe and you can calculate velocity from the flow rate.
It’s a bit more involved than that, since the presence of the grain bed itself reduces the cross-sectional area the water will flow through, increasing its velocity compared to the inch or so of water above the grain bed or below the false bottom.

As stated above, much easier to measure flow rate.
No need to calculate back to velocity.
That said, I did find it interesting that my mash tun guide specified a recommended lauter velocity in inches per minute, while noting its flow rate equivalent in gallons per minute. Other values (min/max) were given in terms of velocity only.

https://ssbrewtech.zendesk.com/hc/en-us/article_attachments/202260693/Infussion_MT_WP_V1.0.pdf

 

[TheMadKing]

Burying the sparge inlet below the grain bed is not ideal.
That aside, as long as you maintain some water above the grain bed, and your input to the lauter tun is delicate enough to not disturb the grain bed, then the velocity of the sparge supply in its tubing is irrelevant.
The sparge supply simply feeds the water that covers the grain bed.

The velocity that matters is through the grain bed.

If you rather specify velocity rather than flow rate, think of the lauter tun diameter as your pipe and you can calculate velocity from the flow rate.
It’s a bit more involved than that, since the presence of the grain bed itself reduces the cross-sectional area the water will flow through, increasing its velocity compared to the inch or so of water above the grain bed or below the false bottom.

As stated above, much easier to measure flow rate.
No need to calculate back to velocity.
That said, I did find it interesting that my mash tun guide specified a recommended lauter velocity in inches per minute, while noting its flow rate equivalent in gallons per minute. Other values (min/max) were given in terms of velocity only.

https://ssbrewtech.zendesk.com/hc/en-us/article_attachments/202260693/Infussion_MT_WP_V1.0.pdf

I fully understand all of that, but your first two sentences were what I was referring to.

So not counting all the reasons it could be a potential issue, it's not an issue [emoji16]

 

[FunkedOut]

This effect is quantified in the chart I posted above. The horizontal axis is the ratio of grain bill weight to pre-boil volume. This means that a 12 lb grain bill with a 6.5 gal pre-boil volume has the same efficiency as a 24 lb grain bill with a 13 gal pre-boil volume. If you boil both with the same boil off rate, you have to boil the larger batch twice as long to get rid of the excess water (assuming you want a post-boil volume ratio of 2, say 5.5 and 11 gal.) If you don't use the extra water in your double batch, the efficiency will go down.

Things get even worse if you want to make a big beer, say 18 lb of grain for your 5.5 gal post-boil volume. Now instead of 6.5 gal pre-boil, you will need 9.75 gal pre-boil to maintain the same lauter efficiency as the smaller beer. At a 1 gal/hr boil off rate, you'd have to boil more than 4 hrs to lose 4.25 gal rather than 1 gal during the boil.

Brew on

It’s cheaper and faster to take the hit on effeciency rather than consuming more water and energy to boil longer.
Water is cheap, and electricity may be way cheaper than propane, but grain is cheap too.

I grew tired of trying to nail my brewhouse effeciency for predicting grain bills and gravities. I was always real close but sometimes off by a couple to a few points.
I chased this idea by plotting the last couple of years worth of brews; Target OG versus actual effeciency.
Mash thickness held constant, pre-boil volume held constant.
I don’t recall the difference being as high as 20% for my system.
Let me dig that graph out...

(BRB)

 

[FunkedOut]

I made it back.
Here is that graph:

Not exactly two years worth, but from June 2018 through October 2019.
I separated 2018 from 2019 into two separate series because I changed my recirculation flow rate from one year to the next;

• 2018 = 0.5 gallon/min
• 2019 = 1.75 gallon/min

The sparge rate always remained at 0.5 gallon/min.
Not a big difference between the two.

The third series (green) is both years combined.
The dotted lines are linear approximations of each of the series.
Their respective formulas can be seen.
Utilizing the formula for the combined series, I created this chart that I use when estimating the grain bill:

You can see a 20% spread between a 1.030 OG (~3% ABV) beer and a 1.106 OG (~10% ABV) beer.
Seldom do I make a beer above 1.070 OG (~7% ABV) and very rarely will I make a beer below 1.050 OG (~5% ABV). There's only a 5% mash efficiency spread for me in that range.

I will take the target OG of the beer I am about to brew, calculate the expected mash efficiency and use that as my efficiency target when estimating the grist.
Very useful when stepping out of the norm and reaching for a big beer.