Using electronic scales for running gravity reading

[ArgM]

Hey guys!

This is my first post, how exciting!

I'm studying Industrial Design and I am about to begin an electronics and prototyping subject.
With this I was hoping to adapt my assignments to make a simple electronic device that will record all the data coming from the brew to then understand
what's happening where and how that relates and interacts with other parts of the process . I realise that their are very well down products and devices that already exist,
how ever, this is irrelevant since the main grading will be based on the efficacy of the electronics and the development of the prototype.

Now, I want to swing this one more for people using a simple set up and doing small batches, so they can fine tune in between each batch (I currently take 10 - 18L yield per brew). So, I am planning on putting in all the relevant temperature and volume readers from weighing the grain right through to carbonation.

My question is: Would zeroing out the fermenter on a set of scales, working out the initial water gravity of the water to then find out OG by dividing its mass by the water reading, then using this reading to take a running gravity and FG reading be an effective and precise way of capturing the data electronically, with out manually siphoning and reading with a hydrometer?

Thanks

 

[Toper]

It certainly would be.The only problem with a sample that size is that you need very accurate liquid and weight measurements.You'd need to calibrate the fermenter for volume to a very tight degree,and use scales that were accurate to withiin a very fine limit.Much easier to use a volumetric flask of 100ml (100ml=100g of water) and some jewellers scales that are accurate to within .000

 

[ArgM]

Yeah, that 'accuracy' I think may be more effort over manual readings the more I think of it...
I guess that leaves me with powered siphon into a weighted scale to take the readings intermittently or finding a similar electronic sensor like in that 'BeerBug' Kickstarter?

 

[Ducatiboy stu]

One wsy you could do it is to have a big balance scale setup. One side has your ferm and the other side has another vessel filled with water so they both weigh the same. As your brew ferments it will change in weight. You could then remove water from the water filled vessel to even them up, measure the amount of water removed and work out what the change is. You would need to acuratly weigh your fermenter first.

Be a PITA to setup but it would make an intetesting project.

 

[ArgM]

That would be good, the issue with that is it would give an analog reading that I would then have to set something up to read and convert.
However, having said that, I'm sure there would be a 'reader' that could sit on the balance point that could do the job with that set up.
Also, if anyone know a way of measuring the complexity of sugar during mash that'd be cool to have

 

[TheWiggman]

I reckon it's doable* provided you had an ultrasonic level sensor or similar to detect the height of the liquid before fermentation (krausen would dick around with it).

Consider a batch going from 1.050 to 1.010

Fementer - calibrate scales to be zero with it, including airlock and liquid
Original wort - 23l @ 1.050 = 24.15kg
Beer - 23 @ 1.010 = 23.23kg

As long as you know the actual volume, which you could calibrate pretty accurately from a ULS, if you had scales that were accurate to a gram then you could know your SG pretty accurately I reckon. It's a loss of 920g which is pretty substantial observing the liquid alone.

*This assumes there are no solids in the liquid. Fermentation causes flocculation resulting in solids and yeast settling at the bottom. You're not actually changing the mass of the contents inside the fermenter but rather separating materials of different densities. Hence total mass may be 24.10kg after it's done, maybe, with the stuff at the bottom with an SG much greater than the FG. You're then talking about a 50g range to measure over, which is a different story. I'd be surprised if it's this much.

I'd maybe look at something buoyant on the inside held down by a load cell. As the density changes so would the measurement on the load cell, but then we're no longer in the 'simple' territory are we?

 

[Ducatiboy stu]

You will loose mass with CO2 production.

 

[Ducatiboy stu]

That would be good, the issue with that is it would give an analog reading that I would then have to set something up to read and convert

You could easly calibrate the centre pivot pointer in gms against a scale

 

[Aydos]

Wouldn't the mass increase with the growth of yeast cells?

 

[MCHammo]

Wouldn't the mass increase with the growth of yeast cells?

No. The yeast eat the sugars, etc in the wort. They use the materials and energy from this to produce new cells. Since no new mass is being added to the fermenter during fermentation, the contents of the fermenter cannot increase in mass.

 

[schrodinger]

Measure the CO2 loss, which will be directly proportional to the rate of sugar depletion and ethanol production. Easy in a fermenter. Put a CO2 sensor in the headspace and measure the air flow out via the airlock. The latter will require some cleverness -- maybe use a mechanical principle akin to a tipping bucket rain gauge. Or you can use a gas mass flow meter (but I assume cost is an issue and an MFM is pricey).

Any way, the co2 flow is just the concentration times the flow rate. Too easy.

 

[Grainer]

build A fermenter with a built in reader that can easily be sanitised at low cost

 

[Ducatiboy stu]

build A fermenter with a built in reader that can easily be sanitised at low cost

and pressurised...and temp controlled...

 

[schrodinger]

The other problem with a mass based approach is that you'll also lose mass through evaporation (via air that leaves through the airlock). To account for that would require an approach akin to what I described above for CO2 anyway.

In fact, the only mass you'll lose will be through CO2 (as noted by Stu), H2O and ethanol, except for a tiny loss of volatile organics. Everything else is just metabolism -- conversion of one thing to another, which will change density but not mass.

 

[Ducatiboy stu]

I can see a Nobel Prize....or at least an Ignobel Prize in this project...

Would actually be interesting to see what sort of weight difference there is between begining and end of fermentation.

 

[Mr. No-Tip]

I use a hydrometer.
And sleep in a bed with my wife.

Nah, just kiddding. Sounds interesting. I'll be interested to see if this goes anywhere.

 

[TheWiggman]

Schrodinger's got it, but it would be a bit of a ball tearer at those rates wouldn't it? It won't take into account any leaks. For me about every 2nd brew won't bubble through the airlock because the seal isn't perfect.
I think the easiest way would be to do a high gravity, small batch with a strong yeast. Measure the change in mass following fermentation and correlate this to the change in SG. You should end up with a simple factor, which you could then plot on a graph as % of starting mass vs. change in SG.

The other thing I didn't consider was losses due to evaporation (through the airlock). It would be minimal, but would be a function of temp and surface area and should still be considered.

 

[schrodinger]

You're absolutely right, leaks could be a big issue. Easy to fix with some vacuum grease if you use a screwtop fermenter with o-ring. (Edit: or a carboy.)

Another way to measure flowrate is to replace the airlock with a resistive pathway of known resistance (perhaps a length of HPLC tubing) and measure the gauge pressure in the headspace. We do something similar to measure water flow in leaves. The biggest challenge here (assuming you've ruled out leaks) is to keep krausen from plugging the tube.

 

[MastersBrewery]

This may be of some use LINK

 

[ArgM]

MastersBrewing that looks pretty perfect!
I'm wondering if its worth using both the scales and the sensor? It sounds like both could offer small amounts of information.
The sensor should also give an indication of SG during mash and boil?