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Author Topic: Auto-monitoring fermenter  (Read 956 times)

Offline dsdavidson

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Auto-monitoring fermenter
« on: July 13, 2015, 10:30:34 pm »
A friend/brewing buddy and I have recently been toying with some ideas for a self-monitoring fermenter, and I would very much like to hear what you all have to say about these ideas, or any ideas you have had for similar builds, successful designs, etc. The two ideas that we have come down to are illustrated below. BEHOLD my mighty MS paint masterpieces.

The idea here is basically to be able to watch the SG very carefully throughout the entire process, without disturbing the wort or allowing O2 to be introduced into the headspace by taking overly frequent samples. And no, neither of these is necessary but I am a curious dude and would like to be able to watch the process more precisely.

Idea 1: Attach a clear tube to the side of the fermenter with ports above and below the water level, sealed on the top, and leave a floating hydrometer in there throughout fermentation.


Idea 2: Insert a digital pressure sensor near the bottom of the liquid, high enough to not get into trubble  ;D and attach it to an arduino microcontroller and, using the formula p=rho*g*h where p is pressure, rho is density (i.e. SG), and h is the height from the top of the liquid, solve for rho.

Images to come once I figure this technology stuff out

« Last Edit: July 13, 2015, 10:57:26 pm by dsdavidson »
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Offline smkranz

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Re: Auto-monitoring fermenter
« Reply #1 on: July 14, 2015, 06:51:03 am »
Cool idea.  Just happens that I recently deployed the new BeerBug I purchased at the AHA conference.  It monitors gravity, temperature and alcohol, uploads data points to a cloud server every 15 minutes, and let you see it on desktop or smartphone app.  My current fermentation is here:

https://www.thebeerbug.com/main/index.php?id=20000c2a690a323b

The historical graphing is off, because I was not able to properly calibrate the Bug until this morning.
Steve K.
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Offline a10t2

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Re: Auto-monitoring fermenter
« Reply #2 on: July 14, 2015, 12:00:15 pm »
The hydrometer trick won't work because it will get fouled by krausen. The only way I can think of to compensate for that in a BeerBug-type device would be to make it really heavy, but maybe they've come up with something clever.

The pressure sensor might work if you can find something with both the range and precision needed. Calibration would still be tricky; local variations in gravitational acceleration alone are higher than the ±0.0005 SG you're probably looking for. How are you going to compensate for the drop in wort column height during fermentation?

I think a digital refractometer would be the way to go, but that's probably no surprise.
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Offline dsdavidson

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Re: Auto-monitoring fermenter
« Reply #3 on: July 14, 2015, 10:17:22 pm »
The hydrometer trick won't work because it will get fouled by krausen.


That was what I had figured as well. The change in height differential is an issue that I have not yet though of a solution for, suggestions are welcome! As far as using a refractometer, my concern was primarily with getting it properly positioned. In other words, how would one ensure that the liquid through which the light was refracting was exactly the right thickness (for lack of a more science-y term). Precision with the pressure sensor had not occurred to me.
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