Fermonitor

[Gfei]

Does anyone have any experience with the Fermonitor? I had the thought to build something like this myself as a neat project and didn't even realize this existed.

What I'm trying to find out is what this device uses as a sensor for density measurement. I'm guessing it is either thermal mass flow or capacitance, but I'm not sure if wort/beer is a good enough dielectric for a capacitance device.

Does anyone around here know how conductive wort/beer is??? Would it make a reasonable capacitor dielectric for measurement purposes?

If there are any fellow techies on the boards here that can help I would appreciate it.

thanks

 

[jfkriege]

You might check out FermTroller, a mod for the BrewTroller software. They also have a forum that would be helpful if you want to know specifically about their product. Just Google it.

I have not seen anyone come up with a good and inexpensive way to do density measurement. If you do it, let us know.

 

[ChemE]

How about two dp cells one placed 1cm lower than the other?

 

[Gfei]

Yeah, there are about 100 different ways to measure density, each good for it's own specific use. There are quite a few variables to account for with measuring fermenting beer. It's looks like a lot of fun to try though (depending on your definition of fun).

 

[gunner65]

Analog method

http://www.brewballstore.com/

 

[Gfei]

Analog method

http://www.brewballstore.com/

Yeah... but I can't monitor that electronically.

 

[gunner65]

Yeah... but I can't monitor that electronically.

Just put a web cam on it!!!!!

 

[sacrifice]

Well, now I have another toy to buy - BrewBalls - too funny. Maybe I will buy a set or two and put a streaming cam so everyone can watch my BrewBalls rise and fall..........

 

[sharpk60]

I'm also really interested in the Fermonitor. From the pictures on fermonitor.com, I suspect that the Fermonitor uses the hydrostatic pressure method of determining density (described here: http://en.wikipedia.org/wiki/Specific_gravity#Digital_density_meters).

I've done some experimentation in this method with some inexpensive differential pressure sensors from Freescale (described in my blog: http://sharpk60.blogspot.com). Unfortunately, these sensors don't seem to have the accuracy to measure the relatively small pressure differences generated by the density changes in a 5 or 6 gallon carboy. I've found some more accurate sensors but they're quite a bit more expensive and I haven't dropped the cash to buy them yet.

I haven't tried it myself but I've read in several places that measuring the capacitance wouldn't work well while fermentation is going on because there's too much gas (CO2) mixed in with the liquid and that would make the readings too inaccurate.

 

[Boerderij_Kabouter]

Indeed, HBT is the birthplace (or at least the jumping point) for the fermonitor...

https://www.homebrewtalk.com/f11/fermonitor-lives-93194/

I believe it will kick a lot of ass.

 

[Quaffer]

I'm also really interested in the Fermonitor. From the pictures on fermonitor.com, I suspect that the Fermonitor uses the hydrostatic pressure method of determining density (described here: http://en.wikipedia.org/wiki/Specific_gravity#Digital_density_meters).

The sensors are not displaced vertically which seems to be necessary for the hydrostatic method.

My bet is on the vibrating element transducer, perhaps by ultrasound.

There is no information about accuracy in various conditions which would be necessary for me to buy one, let alone lowering the cost.

Seeing the post about the brew balls made me think about another method, which is described in your Wikipedia link: Buoyant force transducer. Take for example a ping-pong ball, submerge it in the fermenter and measure the force by which it is trying to float, perhaps with a strain gauge. The force is proportional to the density from which we can calculate SG and all that. I suppose there would be some inaccuracy because of small bubbles of CO2 sticking to the ball.

 

[Gfei]

I'm liking the resonant frequency measurement more and more for this.

Like this