Hydrometer

[Frjen]

Hello

My wine is not ready and I want to find out the alcohol %, I did a hydrometer in the beginning and I'll make the last one as soon as I undersand the formula. It's always OG - FG and then multiply with a number, but people use many different once.
My question is what does OG and FG stand for and wich number should i multiply with and where does it come from ?

 

[Julie]

OG - original gravity

FG - final gravity.

You will, also, see SG, which will be starting gravity or specific gravity.

I use:

OG - FG X 131

 

[JerryF]

OG - original gravity

FG - final gravity.

You will, also, see SG, which will be starting gravity or specific gravity.

I use:

OG - FG X 131

Have also seen, and one I use most of the time, OG-FG/0.0074. Not sure it's any better than or different than what Julie has here but it's the first one I used so I guess just because of familiarity, I've stuck with it. Jerry

 

[kryptonitewine]

Both calculations will give you the same result, or at least very similar results. 1/131=.0076. So the difference of .0002 won't cause a dramatic difference.

 

[DoctorCAD]

Both numbers are almost identical, use either one. Most people seem to like multiplicstion vs.division.

 

[Frjen]

Have also seen, and one I use most of the time, OG-FG/0.0074. Not sure it's any better than or different than what Julie has here but it's the first one I used so I guess just because of familiarity, I've stuck with it. Jerry

Where does the number 131 come from ?

 

[cpfan]

Where does the number 131 come from ?

It's really not that important where it comes from. For example, is it important where the 2.2 comes from when converting from kilograms to pounds? (IE #pounds = #kilograms * 2.2.) It's just a conversion factor.

BTW, I prefer (OG-FG) * 133, as the results are closer to the readings on my hydrometers.

If you have a triple scale hydrometer, you can readily change the initial sg (OG) reading into a Potential Alcohol (PA) reading. Then adjust it for the PA associated with the final sg (FG) reading.

When using any of the formulae, it is necessary to be certain that all readings are proper and preferabaly 3 digits. For example, folks regularly post incorrect or impossible sg readings (recently saw 1.3).

OG readings should be 1.080 to 1.120 depending on the wine (ports and ice wines will be higher, mist wines lower). FG readings should be .990 to 1.000 (ports and ice wines may be higher).

Steve

 

[SBWs]

Only thing I've ever found that explains where the numbers come from.


Where 1.05 is the number of grams of ethanol produced for every gram of CO2 produced, and .79 is the density of ethanol,

https://en.wikipedia.org/wiki/Alcohol_by_volume#cite_note-11

Simpler formula:

 

[saramc]

I don't know if this interests you but this site, http://dd26943.com/davesdreaded/tools/convert.htm , has a formula which allows you to plug in temperature, OG, and then temp + FG and does the temp calibration and gives you your ACV or ACW.

*Sara*

 

[cpfan]

I don't know if this interests you but this site, http://dd26943.com/davesdreaded/tools/convert.htm , has a formula which allows you to plug in temperature, OG, and then temp + FG and does the temp calibration and gives you your ACV or ACW.

*Sara*

That site assumes that your hydrometer is calibrated at 60F. Mine is calibrated at 68F. Not a big issue, but means that the extra accuracy of their calculations is wrong.

Steve

 

[saramc]

That site assumes that your hydrometer is calibrated at 60F. Mine is calibrated at 68F. Not a big issue, but means that the extra accuracy of their calculations is wrong.

Steve

Noted...this tool works for me since my hydrometer is calibrated at 60F

 

[Luc]

It's really not that important where it comes from. For example, is it important where the 2.2 comes from when converting from kilograms to pounds? (IE #pounds = #kilograms * 2.2.) It's just a conversion factor.

BTW, I prefer (OG-FG) * 133, as the results are closer to the readings on my hydrometers.

I disagree Steve. I think it is important where the numbers originate from. it will give you a better understanding about making wine. In making wine numbers are important as you need to calculate sugar contents etc.

Well here we go.

Every point in the SG scale equals 2.6 gram sugar.
In a must with an SG of 1.085 there will be 85 x 2.6 = 221 gram sugar (globally).

Half of that will be transformed into alcohol: half of 2.6 = 1.3.
There we are. And actually it is not half but 0.56% and that leads to the 1.31 figure.

What do you say ????
In a liter water there have to be 221 gram sugar ???
Well indeed half of that will be alcohol being 110 gram and that is 11%.

There we are.

Luc

 

[Frjen]

I´m making a rapport for school and if i mention the number 105 og 131 I need to know the source of the number.

 

[Luc]

It's really not that important where it comes from. For example, is it important where the 2.2 comes from when converting from kilograms to pounds? (IE #pounds = #kilograms * 2.2.) It's just a conversion factor.

If you have a triple scale hydrometer, you can readily change the initial sg (OG) reading into a Potential Alcohol (PA) reading. Then adjust it for the PA associated with the final sg (FG) reading.

Steve

Yes it is Steve, I disagree with you.
Why use 1.085 as a lead for your SG if you do not know what the number is about. If you do not know or want to know these things why measure at all ??? It is an essential part of this hobby.

2.6 grams sugar makes the Sg go up 1 point.
Half of it wil convert in CO2 and half of it will convert in Alcohol.
Half of it is 1.31. There is the figure you need.

I am doing a series on measuring alcohol on my web-log. All the methods and systems will be explained there.

www.wijnmaker.blogspot.com

Luc

 

[FABulousWines]

2.6 grams sugar makes the Sg go up 1 point.

That depends on the volume.

 

[Frjen]

Why eould someone the use 105 ?

 

[Frjen]

Why eould someone the use 105 ?

Why would someone then use 105 ?

 

[cpfan]

Wow this is a strange thread.

Luc: do you realize that you just repeated what you said in April? It's interesting to see where the 131 comes from.

BTW, this site (http://www.brsquared.org/wine/CalcInfo/HydSugAl.htm) says 268 g of sugar per litre yields an sg of 1.100. Half of that is 134. Personally I suspect that there are some rounding errors in all of these numbers.

frjen: Not trying to confuse you, but the 105 is actually 133. Because that formula is 1.05/0.79, which happens to equal 132.9. Personally I have used fg-og * 133 for years. These are all different formulae that different people use to get an approximate result. If you take a set of numbers and try the different formulae, they's probably come out within 1%.



Steve

 

[Frjen]

I found this euation online, abv = (stadting sg - final sg) /7.36
Can someone tell me where the 7.36 comes from?

 

[Luc]

Wow this is a strange thread.

Luc: do you realize that you just repeated what you said in April? It's interesting to see where the 131 comes from.

Steve

Yep,

Did not read the thread very well now, did I ???

Luc