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measuring efficency

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Joe Sr.:

--- Quote from: rjharper on December 06, 2012, 11:15:31 AM ---
--- Quote from: anje on December 06, 2012, 11:08:25 AM ---Similarly, I'm curious how you all measure volumes accurately, particularly for top-offs, post-boil, etc. Clearly you'll need this for efficiency calculations.

I've been going by the graduations on my fermenter buckets as best I can, but I can't even pretend that those are particularly accurate. Is there a preferred way?

--- End quote ---

I calibrated each of my primaries when I got them.  Some of the buckets were close, others off if the printing wasnt right.  I also calibrated and etched my glass carboys.

--- End quote ---

I did this with my carboys and better bottles, too, ages ago.  I know it's lazy, but with the last two better bottles, I just put them side by side and marked the volumes from the old bottle.

I fill my kettle from jugs that hold 2.5 gallons so I have a good idea how much water is going in.  Not completely accurate but for the most part I get repeatable results.

Kaiser:
I think there is some value in keeping track of efficiency. At least at the stage at which you care for it. I measure post boil volume and gravity, but am mostly interested in gravity since I always brew more than I can fit in the fermenter.

I also tend to keep track of conversion efficiency since at this point may still be able to fix it.

On the topic of accurate measuremets, you may want to play around with my efficiency analysis spreadsheet (http://braukaiser.com/documents/efficiency_calculator.xls) it allows for input of measurement errors and does a full error propagation to the result.

with these errors:

grain weight +/ 10g
grain extract potential +/- 2%
gain moisture +/- 1%
wort volume +/- 0.2 l
gravity +/- 0.2 Plato

I get an average error of a little less than +/- 3 percent points for the efficiency of a standard 5 gal batch.

Kai

mtnrockhopper:
I calibrated my carboys using jugs and I'm pretty sure their accuracy is questionable. I calibrated my kettle by weight (8lb / gallon), which I think is better. It is only as accurate as the scale though.
 
I don't calculate efficiency. I just note if the OG is off and adjust over time. Beersmith is set at 70% which seems to be working. I don't try to fix it and just buy a little more grain.

goschman:
The buckets that I use are not calibrated over 5 gallons and I normally get a post boil volume of about 5.5 gallons. Efficiency has been bugging me a lot lately. Since I don't get a very accurate post boil volume reading, I have decided to take pre boil gravity readings since I know what my beginning volume is. If I have accurate grain potentials then my efficiency should be pretty accurate.

I can then use the post boil gravity reading to calculate my post boil volume. For instance, a preboil gravity reading was 1.048 for 6.5 gallons but the post boil reading was only 1.052. I ended up with a post boil volume of 6 gallons which seemed about accurate after looking at the level on the bucket. In the past I would have put 1.052 for 5.5 gallons which would have significantly lowered my efficiency.

Is this a decent method to use?

a10t2:

--- Quote from: goschman on December 06, 2012, 12:15:49 PM ---Is this a decent method to use?
--- End quote ---

I don't think there's anything wrong with it, but what purpose does it serve? If you've hit the target OG and you have enough volume in the fermenter to net your desired packaging volume after losses, what else matters?

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