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SOLVED - Derived expression - using first value

Hi,

I have set up a a device to help with brewing and to determine the fermentation of wort to alcohol.

I’m trying to set up a derived expression to calculate the alcohol by volume measurement as a % the formulae is.

ABV =(76.08 * (og-fg) / (1.775-og)) * (fg / 0.794)

OG= Originating gravity before fermentation - i.e. the very first reading
FG= Final gravity - i.e. when the wort has finished fermenting, this will decline until the beer is finished

Is there a way using my data to take the first ubidot value for SG (it would literally be the first entry) and use this within a derived expression?

I can edit the expression manually each time i.e. 1.040 being the starting gravity, but this will vary from beer to beer.

(76.08*(1.040-FG)/(1.775-1.040))*(fg/0.794)

FG wouldn’t need to be changed as this will be the most recent value.

Can anyone give me any pointers please?

Thanks

Mik

Solved, needed to add in OG as a rolling variable over a predetermined timescale.

Hi,

I’ve tried to replicate this formula as a synthetic variable, but I’m not getting any results.

The variables are: OG (the first measured density reading) and FG is the last density reading the device takes every 15 minutes.

Can someone help me put this formula as a synthetic variable?

Thank you

Hi @Miguel_M_V,

Could you please share the synthetic formula so I can help you checking what could be wrong?

Looking forward to your response.

Best,