Ah, "Eric to the rescue"
I do worry that I'm hiding an important message under mountains of high-browed (for me!) maffmattykul stuff. I started out to create a bit of mischief (I can't easily read hydrometers and haven't touched one for eons), but these pickynometer things are panning out to be very viable alternatives. I hope my attempts to be clever haven't scared too many folk away?
...
But, just one more crack at being a clever dick...
- Dodgy-1.JPG (175.91 KiB) Viewed 12360 times
I was attempting to sweep some dodgy maths under a virtual rug. Here's an example on the "Automatic Use" page of the spreadsheet (there's a near identical example on the "Manual Use" page). They are in the "Curiosity Only" areas and high-lighted with the dotty fill (which Google Sheets refuses to display). Zooming in the "dodgy" cell it has the contents:
(Sample_Weight / Water_Density_at_Calibration_Temperature * Water_Density_at_Sample_Temperature) + Bottle_Dry_Weight
Ignore the "bottle dry weight", that's just to have the cell display the
total weight of the filled pyknometer. The sample is beer or wort. But the densities are for
water. Hence "dodgy"!
"Dodgy" 'cos the beer/wort is a different SG to water? Nay, make adjustments for things like that and because you are doing it to two values (at the two temperatures) then they just cancel each other out. In fact, those density figures could be trimmed down a bit for this and they'd still do the job:
The "density figures" only describe a point on a curve, and I'm using a curve derived from the changes in density due to temperature in
water as there can't be data for beer or beer wort 'cos of too many variables. "Dodgy", but I'm hardly comparing beer with something like mercury, and I'm trying to be "open" about my "dodginess". You won't find such discussions with hydrometers, yet those things are based on far dodgier stuff.
It's great, I can manipulate mathematical stuff so much more easily now (talking about
beer at retirement age) than I ever could at school (a paltry Grade C at Maths "O" Level!).
The spreadsheet also shows the results using the different "Tare Weights". The purely calculated "manual" (black) box always shows the "reality". The coloured boxes show a jumble of results as the weighing scales would indicate (i.e. "stand-alone" mode). It would allow you to pick the most appropriate Tare weight, should you need it (I think not). The apparent "jumble" is because they are all at the same temperature, as indicated by the apparent calibration temperatures: E.g. "
SG 20°C/20°C". The first temperature is the sample's "calibrated" temperature (which I'm using in the "simulation" to be the assumed actual temperature), and the second is the calibrated temperature of the water "reference". The "manual" (black) box might be very slightly out of compliance because of the "tricks" I used to calculate the "Tare Weights" (but remember, the spreadsheet is showing SG with
four, not three, decimal places). If I allowed the simulation to show the results at the calibrated sample temperature it would come out as the not very useful:
- Dodgy-2.JPG (23.11 KiB) Viewed 12360 times
...) ...
):
