Inputting OG and FG readings for ABV

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jkmeldrum
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Inputting OG and FG readings for ABV

Post by jkmeldrum »

Hi all

I'm a relatively new user of BTP and I was just after a quick bit of help.

Under the Analysis tab it asks for OG Reading and TG reading for a brew.

I use a refractometer....Does the TG reading have to be adjusted for alcohol like it does in Beersmith?

Or is BTP asking for just the reading off my refractometer and it does the adjustment for me, because my alcohol percentages seem to be way off.

Cheers

Justin
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slothrob
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refractometer

Post by slothrob »

You want to put in the gravity adjusted for alcohol.

You can get that value by using the BeerToolsPro Refractometer SG Calculator found in the menubar, under Window>Calculators>SG>Refractometer.
BTP v2.0.* Windows XP
jkmeldrum
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Re: refractometer

Post by jkmeldrum »

slothrob wrote:You want to put in the gravity adjusted for alcohol.

You can get that value by using the BeerToolsPro Refractometer SG Calculator found in the menubar, under Window>Calculators>SG>Refractometer.
Thanks for the reply,

I must be dumb because I can't seem to get that to work for me very well....or I'm doing something wrong.

I had an OG reading of 1.050 and my TG reading was 1.021 (uncorrected).

I've selected refractometer at the top of the tools windows under S.G.

There are then 5 data fields below....am I supposed to fill out all of these with values or just the OG and FG values in SG?

If I put in 1.050 in original gravity field and 1.021 in final gravity field it gives me a Wort calibration value of 1.050, original brix 0.0 and terminal brix of NAN(000).0.

I thought if i just put in the OG and FG values, it would convert those values to brix in the original brix and terminal brix fields, and give a wort calibration value somewhere in the 1.009 range?

Hope that makes some sort of sense?

Cheers
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slothrob
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refractometer correction

Post by slothrob »

The calculator assumes that, since you are using a refractometer, you are measuring in Brix. If you put in the pre-fermentation brix reading, it will give you the OG in gravity. Then, if you enter the terminal brix reading, it will give you the FG in gravity, corrected for alcohol content.

If you read your gravities with an hydrometer, you can enter the values in SG, but it will give you the Brix reading you would have had if you had used a refractometer.

I believe the Wort Calibration value is fixed, and should be 1.04.

When I enter 1.050 into the OG field, I get 12.67 original brix. Then, when I enter 1.021 into the Terminal Gravity field, I get 8.4 terminal brix.
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jkmeldrum
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Joined: Fri Aug 26, 2011 1:34 am

Post by jkmeldrum »

Thankyou thankyou thankyou....

it finally makes sense!

My refractometer has a dual scale so I'll take the reading in Brix from now on....also don't know why my Wort calibration allowed me to change it to 1.050 if it's supposed to be fixed, but anyway I've changed it back now.

Now I'm getting the proper corrected value when I type my original readings in.

Appreciate your help...

now I can get rid of Beersmith forever!!
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Post by slothrob »

jkmeldrum wrote:....also don't know why my Wort calibration allowed me to change it to 1.050 if it's supposed to be fixed, but anyway I've changed it back now.
By fixed, I mean it is generally accepted to be 1.04 for wort. Some brewers may want to change it if they have calculated a different value for their refractometer or the specific wort they produce.
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jkmeldrum
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Post by jkmeldrum »

Thanks for that

I'll compare to the values that I get out of Beersmith and if it's close enough, that's where I'll leave it.

Cheers

Molly
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