BeerBug

[Shane Phelan]

Fermentation converts sugars to alcohol and carbon dioxide. If you know your starting sugar concentration and you measure the CO2 formation you would be able to track the process.
Does anybody know how to reliably measure the gas given off? :-/

Interesting idea. All you need is a gas flow meter for that which could be easily hooked up to an arduino or pc.

Only issue is getting some sort of reference in terms of volume of CO₂ produced per point drop in gravity.

[MrChalky]

I had considered doing something along these lines last year.
My solution was to calculate the density of the liquid using 2 pressure sensors.
The sensors would be mounted in a probe in the wort at set depths (the actual depths aren't important, the difference between them is).

From this you can work out the density:
Density = (P₁ - P₂)/(9.81d)

Where:
P₁ = the pressure at the lower sensor
P₂ = the pressure at the higher sensor
d = the distance between the 2 sensors

From this you can work out the specific gravity
SG = Density_wort/Density_H2O
(At a certain temp - so use a temperature sensor mounted in the probe to get this)

I don't know though if the sensors will be accurate enough, and the last time I went looking for pressure sensors, they were madly expensive.

[Shane Phelan]

Here is a way to do the calculation from gas production.

Only 1 sensor required.

[JimmyM]

Id love to be able to understand all that
Maybe if i read it a few more times.
pesky moles!

[delzep]