"Don Shesnicky" wrote;
> > Guy
> It's a virtual sale, you use your own water, sugar and tools
> and just send me the money.
> Boy I hope this works...
> > > When is that going on sale?
> > > Guy
> > It's a virtual sale, you use your own water, sugar and tools
> > and just send me the money.
> > Boy I hope this works...
> > Don
> It's a deal. Here's $9.95 virtual money. Don't spend it all in one place!
I just checked the issue of Brewing Techniques (vol 7, #3), and it is
claimed that indeed the error is not constant, and that it may be greater at
higher gravities. There were several reasons given, but one I recall is that
diameter of the tube often varies slightly and the thickness of the tube
glass may vary over the length as well.
> I should have that issue of Brewing Techniques*** around. I'll see if I
> can dig it up and post the Author's basis for non-linearity.
> > That is correct, the scales a not linear, I just measured my Dujardin
> > Salleron hydrometer. at around 1.000 its a .40" for 10 degrees, at
> > around 1.100 it's around .32" for 10 degrees, that is a 20%
> > difference.
> > I have Kesslers, cheapos and the French hydrometers mentioned above
> > and have the ability to calibate them. In a month or so I will have
> > some time available and will calibrate them and post the results.
> > Nice catch, I am a metrologist and always considered them reasonably
> > linear, that what winemaking texts usually say.
> > PS: Jack, I have half of those hydrometer values entered into a
> > spreadsheet and will post that too. ( I got the hydrometer scales
> > from NIST and am hand entering them into a spreadsheet for
> > manipulation.)
> > Best regards
> > Joe
> > > I recall reading an article in "Brewing Techniques" vol 7 #3, a great
> > > magazine which died a couple years ago, that suggested the error curve
> > > not simply linear, and that a hydrometer reading 1.000 in water at 60F
> > > in fact be off as the gravity increases. If your unit reads, for
> > > 1.002 in your calibration water, you cannot just subtract .002 from a
> > > gravity reading as the error increases as gravity increases. The cheap
> > > hydrometers typically have an error of 10% +/- This means that in a
> > > solution of 1.050 a $5 hydrometer could read between 1.045 and 1.055.
> > > for $5 you get a unit that is OK for low readings, but not so great for
> > > readings. A more accurate scientific hydrometer which has a small range
> > > spread over a long tube can be had for about $30US
> > > Steve