Incorrect Scale Hydrometer Blues

Hi, I thought I had already posted this, but I hear no one else but me can see it so I post again.

I wonder if you can help me again?

I was talking SG / PA with the guy that turned me on to wine making and he had to correct me on what I thought I knew about SG/PA.

Here is a shot of my hydrometer. I rotated it to show the markings for SG and PA and drew lines across as a visual guide at each major graduation. Is my triple scale hydrometer wrong? It shows the 1.110 as being 'above 17%' etc as you can see. How can a hydrometer be wrong? Or am I missing the point again...

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Jim

Reply to
jim
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Yes, that's incorrect. If the sg scale is right, then the PA scale overestimates by about 2-2.5% at this level, it should be 14.5-15% or so. I'd get a better hydrometer because if one scale is wrong to such a degree, the other ones might be as well.

The PA scales are more trouble than anything else, once you get the hang of things, just go by the sg or Brix scales.

Pp

it so I post again.

to correct me on what I thought I knew

PA and drew lines across as a visual

shows the 1.110 as being 'above 17%' etc as

Reply to
pp

Wow, according to the paper scale in both my hydrometers, 1.110 = ~14%PA ~24Brix. At 17% the SG corresponds to 1.130 -- on my scale. The two instruments were purchased from different sources, about two years apart. Also, the PA and Brix should both be zero at 1.000SG. Is it on your scale?

Reply to
Casey Wilson

That is a bit odd. I wonder if the PA scale on that is calibrated for alcohol by weight instead of volume? It can't be for beer; (beer does not consume all of the dissolved solids but they expect that actually and just subtract final gravity from original gravity to calculate gross ABV). Maybe the Scots report alcohol in a method other than V/V?

Th PA scale in general is more trouble than it's ever been worth either way as I see it.

Joe

Reply to
Joe Sallustio

It's definitely VV, but I did find 5 different ways of calculating PA and some scales weren't too far off what the hydrometer said. I told the retailer about the problem and their reply was that they didn't use PA and it was better to use SG.

I mostly go by SG, but if you buy a triple scale hydrometer, my view is that all the scales should be correct! Oh well, I'll print out some other charts to have for quick reference...

Thanks all for your replies, Jim

Reply to
jim

didn't use PA and it was better to use SG.

all the scales should be correct! Oh well,

My view is that if all the scales should be correct, you should insist on having the retailer provide you with triple scale hydrometer with all the scales correct!

Guy

Reply to
guy

I agree totally, but stupidly its a trip right across town to a place I don't really use anymore. I suppose I am going to continue to use it for its SG readings (which are the same as my other hydrometer) and buy a new one when I am at the store I go to now. It would cost me as much money to take it back and get it returned for free as to buy a new one annoyingly. The store won't pay return postage as they are basically saying that to all intents and purposes, the PA scale is arbitary at best and pointless at worst - many here would probably agree.

They won't fess up and accept it is wrong and the copyright notice is from 1983. It must be right by someone's reckoning or they would surely have changed it years ago. I am sure that there are many here who'd agree. Though I'd have to say that I don't have enough experience or memory yet to judge the starting SG of a must and say "Oh yes, with an OG of x and so much sugar, this wine will be y% at finishing without refering to charts. Seems like the internet wins over my recent real world chart!

Jim

didn't use PA and it was better to use

all the scales should be correct! Oh

Reply to
jim

It really isn't worth the effort, the hydrometer is clearly marked as reading PA in V/V and is also clearly wrong for what you intend it for. It must be ignoring the non sugar solids or something silly like that but it would clearly overestimate your alcohol content so should be ignored. If you want a lot of detail on these scales see Pgs 193-195 of Principles and Practices of Winemaking by Boulten et al. (I looked at it an after reviewing your jpeg I have no idea what the maker was thinking on this scale but maybe you will have better success).

More important than anything, check zero by placing the hydrometer in

20 C distilled water; see if it reads 1.000. If not, either pitch it or compensate, but keep in mind the SG scale is only roughly linear.

You could contact the MFG, I'm sure they have a good reason for using that curve. The Scots are very good instrument makers. Those scales have not really changed for at least 60 years; no one considers hydrometry a very precise measure of alcohol content given the advances in other methods.

Joe

Reply to
Joe Sallustio

Cheers Joe, sounds like a good idea!

Jim

Reply to
jim

This whole thread seems to be full of nonsense. It's a printing error plain and simple. Probably another example of "out sourcing". ;o) Throw it away.

Like Joe said, the hydrometer scales haven't changed in living memory. Seems a pretty good indication that they got it right the first time !! And it still provides the best available information for general purpose winemaking.

Those that work only with grapes will tell you that all you need is a single scale (Brix) hydrometer, and for them this is true. And those that work only with kits and fixed recipes will tell you that all you need is SG, and for them this is also true (in most cases) because that is what is most often used in the instructions that come with kits/fixed recipes. But anyone that works with"country" wines knows that a triple scale hydrometer and a sugar table are indispensible tools of the craft !! And PA is where you most often _start_ when designing your own recipes !!

It shouldn't surprise anyone that the internet is full of misinformation. Or that many of the books on the subject also have errors. Makes it hard for begginers to sort thru all this stuff and make sense of it all....

Get yourself a standard hydrometer. Find a hydrometer/sugar table that agrees with your hydrometer, and you are well on your way to learning about winemaking. HTH

Frederick

Reply to
frederick ploegman

I found 5 different ways PA calculations here:

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Thanks for your commments though. Jim

Reply to
jim

here:

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Jim, That is a very good reference, Ben is very well informed. Those references I was talking about in 'Principles and Practices of Winemaking' are very similar to what Ben describes. The reason I mentioned 60 years was that one of the last good references written (in the US) was by Bates called Polarimetry, Saccharimetry and the Sugars in 1943 or so. NIST still used that reference to calibrate hydrometers last time I checked. I got a used copy (because I'm a geek and had to know...) :)

Joe.

Reply to
Joe Sallustio

Thanks Joe, your input helps validate another source of information for me. I'm not after n'th degrees here, just a reasonable 'likely PA' to help me make easy decisions. I will indeed be after a hydrometer which matches some published scales at least. The SG readings make the grade thankfully for now.

That just leaves me claculating residual sugar in my cranberry-currant wine which is looking dangerously high this close to transfer to secondary at 1060 with two days to go (out of 7 projected at 20C or so) at an average temperature of 21C . Damn my attempts to convert and scale up US Pints to UK litres from a 1 - 6 gallon (US quantities) My maths will let me down even ifmy hydrometer doesn't.

As Terry Garey tells me, 'time is on your side'! A good job, since this newbie in the UK is wishing that they bought a triple scale hydrometer at the other shop... Seriously, thanks to everyone who replies as well as reads (and without prejudice) you help a very new winemaker to learn by his mistakes...

Jim

here:

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Reply to
jim

which is looking dangerously high this close

20C or so) at an average temperature of 21C

gallon (US quantities) My maths will let

Hi Jim, Well, it turns out I'm a metrologist so I can help with those conversions. To begin, throw out logic as to why there are two different gallons.

1 US gallon = 128 US ounces 1 US gallon = 4 quarts or 8 pints. 5 UK (Imperial) gallons = 6 US gallons.

metric conversions:

1 US ounce = 29.6 ml I US gallon = 3.785 litres

I would suggest you not transfer that wine until the ferment slows considerably, at 1.060 you still have a lot of sugar in there. To be honest I never understood this step unless the goal is to get the wine 'more' protected from oxidation by transferring it to a better sealed container as the fermentation slows down. I ferment in pails and carboys; whites go into the carboy sooner for me for that reason.

Joe

Reply to
Joe Sallustio

Jim wrote "I'm not after n'th degrees here, just a reasonable 'likely PA' to help me make easy decisions."

Jim, if you just want a reasonable alcohol prediction here's a pretty simple approach. These equations assume a wine ferments to dryness. Even though a hydrometer will display a negative number for a dry wine, I assume the end point is 1.000 because you can't ferment anything that wasn't there in the first place. And, the negative hydrometer reading for a wine at dryness is due to the influence of alcohol. By using only the starting specific gravity value there is no influence of alcohol. Therefore, I use the difference between starting specific gravity and 1.000 in the calculation.

Alcohol By Volume Calculation Reference; "Homebrewing, Volume 1", by Al Korzonas, pg 31 og = original specific gravity fg = final specific gravity (in the case of wine 1.000)

Calculation of alcohol by weight; %ABW = (og - fg) x 105

Calculation of alcohol by volume; %ABV = %ABW x 1.25

Combined method for %ABV; %ABV = (og - fg) x 131.25

It's simple to set up the "Combined method for %ABV" equation in a spreadsheet...then just plug in the starting specific gravity and get your answer. All you need is a hydrometer that reads in specific gravity...no charts, no tables.

Bill Frazier Olathe, Kansas USA

I will indeed be after a hydrometer which matches some published

Reply to
William Frazier

On Jan 27, 11:14 am, "William Frazier" wrote: (SNIP) Calculation of alcohol by volume;

Bill, You will have to explain this solution!

Guy

Reply to
guy

guy wrote "Calculation of alcohol by volume; %ABV = %ABW x 1.25 ~Bill, You will have to explain this solution!"

Guy- The equations I use for estimating alcohol in beer and wine come from homebrewing books. All of the books listed below have essentially the same eqauations;

"Homebrewing, Volume 1" by Al Korzonas "New Brewing Lager Beer" by Greg Noonan "The New Complete Joy of Home Brewing" by Charlie Papazian

There is an extensive table in the "Handbood of Chemistry and Physics", 40th edition, that gives water/alcohol content in %W/W and %V/V. We're interested, for winemaking purposes, in alcohol from about 7 to 20%. In this range if you divide the alcohol %V/V values by the alcohol %W/W values you get a factor that ranges from 1.230. to 1.247. The values in these old (I used my copy while in college in the 60s) texts were derived empirically and probably are the basis for the 1.25 values used in the alcohol calculation equations.

Bill Frazier Olathe, Kansas USA

Reply to
William Frazier

Bill:

Do you adjust the calculated PA value for wines with residual sugar? E.g.,. if the starting sg is 1.090 and final sg is 1.000, do you get the same result as if the final sg is 0.992? The reason I'm asking is I'm not sure this formula is meant to be used by ignoring the fg values under 1.000.

Pp

Reply to
pp

Pp - I ferment almost all wine to dryness. I use the 1.000 FG value to calculate alcohol because, in my mind, when all fermentables are consummed by yeast, there is nothing left to cause the specific gravity to be greater than 1.000. And, this is just an approximation so I have an alcohol content to put on my labels. Of course, the alcohol that is present causes the actual FG to be below 1.000. If you use the actual FG on your wine label you don't really know how much sugar is in the wine because the FG is affected by alcohol. When I back sweeten I put the amount I've added on the label. All just for infomation so I can discuss the wines at wine club meetings or with people I give wine to as a present.

When I use the equation in beer making the alcohol content value is less meaninfgul...the FG for beer always ends up greater than 1.000. I still run the calculation just to have an approximate value for the label.

Bill Frazier Olathe, Kansas USA

Reply to
William Frazier

Conspicuous by their absence are the _standard_ scales and charts. So, even as a purely intellectual exercise, it lacks any point of reference. And it only serves to confuse the beginner just as it has done you. Your friend saw right away that your hydrometer wasn't standard. Listen to your friend. HTH

As always, just one man's personal opinion.......

Frederick

Reply to
frederick ploegman

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