pp wrote:

> "frederick ploegman" > wrote in message
> >...
>>
>> I wish you luck, Pp. I, for one, will be very much surprised if the PA
>> scale on all of the world's hydrometers turns out to be invalid.
>>
>> Frederick
>
> Alright, here is how the hydrometer PA scale does against some real
> data. The numbers are from info sheets provided by Napa, Sonoma, and 1
> Washington state winery. The wines are marked R (red) and W (white) as
> this is significant.
>
> The columns a Brix, final alcohol, PA per hydrometer, delta
> (hydrometer - actual).
>
> The PA per hydrometer was calculated by B * (12/22) = B * 0.545 (as
> 22B = 12PA).
>
> The table is ordered by the delta.
>
> Where B is given as a range, avg value was taken for simplicity.
>
> Type B Final PA Delta
> R 25.5 13.5 13.9 +0.4
> R 26-27 14.5 14.5 0
> W 25.6 14.2 14 -0.2
> W 25.2 14 13.8 -0.2
> R 24.8 13.9 13.6 -0.3
> R 24-25 13.7 13.4 -0.3
> R 26.8 15 14.6 -0.4
> R 24.2 13.6 13.2 -0.4
> R 26.4 15 14.4 -0.6
> W 25 14.5 13.7 -0.8
> W 23.8 13.9 13 -0.9
> W 23.5 13.9 12.8 -1.1
> W 23.5-25 14.5 13.3 -1.2
> W 23.5 14.2 12.8 -1.4
>
> Average delta all: -0.53; reds: -0.23; whites: -0.83
>
> I'd say not too good overall, particularly for whites. The higher
> alcohol in whites vs. reds makes sense and is well supported in
> literature. But the formula systematically underestimates even reds in
> this sample. Out of 14 wines, 6 are outside of the reasonable +-0.5
> delta, with the worst case being -1.4 (that's Napa, Matanzas Creek
> Sauv B 2001).
>
> Based on this, I think I could argue that the PA scale on all of the
> world's hydrometers leaves something to be desired.
>
> Pp

Would be interesting to see some data from Brix values closer to 22 Brix.
Do you have or could you get data in this area. 25+ Brix values are not
representative of grapes grown in the East. I am wondering if the error
might not be non linear and may in fact be opposite for lower Brix juice.