Real-Time Fermentation Monitor

I would be interested in atleast one.

I was ready to call BS on this, not I am thinking it could be legit... and the answer to most brewers prayers.

Ryan_PA said:

I was ready to call BS on this

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What? Why?

I'm sold....how much?

JVD_X said:

What? Why?

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Too cool to be believable.

looks cool, sounds cool. do you have a picture of the device in a carboy. if this device is priced right you could sell a lot of these. i would be in for 2-3.

Seriously, I've got a vacant USB port just itchin' for some loving

bearduncle said:

Seriously, I've got a vacant USB port just itchin' for some loving

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SWMBO sayes that a lot!

i was just thinkin thats what she said

I had been thinking about this as well. Basically you can measure the speed of sound and the refractive index of the liquid. Based on that you derive alcohol, SG, apparen attenuation and so on. If such a thing could be manufactured and sold for about $100 - $200, I think there would be a market for it.

But I didn't come up with the idea: http://www.sensotech.com/cms/index.php?id=142&file=1A289B0&no_cache=1&uid=685&L=1

Gotta be a <cruel> joke. It's not even close to April.

EDIT: Wait a second, Kaiser is right. Did this guy figure out a way to MacGuyver a stud sensor or something ingenious like that?

GNBrews said:

a way to MacGuyver a stud sensor or something ingenious like that?

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That sounds like a cool idea. I wonder what the output of the actual sensor in the "stud sensor" is and if it could be used to measure sound velocity.

Kai

My alter-ego posted a message over on the Sciencemadness forum to see what the geniuses over there think about the idea. If anyone would know how to make it work, it would be one of those guys.

A simpler idea might be to simply use a hydrometer (not necessarily glass) positioned inside of a vented tube, and just read it's position somehow (optically or electrically). There's a few engineering bugs with that idea, namely the hydrometer contacting the walls of the tube, but nothing that couldn't be figured out.

This batch appears to be finishing up, at least 1 day ahead of the others I have done - not sure why. I re-used yeast from prior batch and it might have had super-powers or something? I have done this before and not noticed any major change in rate. Live and learn. I have been reading through the posts - I think if we all put our heads together we could take homebrew to a whole new level. One thing I want to mention is the use of sound velocity to monitor fermentation has a critical flaw - it is good for still liquids but it is near useless in a multi-phase solution where you have liquids, solids and gas. For example, in the case of US patent 4959228 the authors provided an effective method and apparatus for liquid density measurement using sound speed measurement but encountered difficulties for multi-phase solutions due to the presence of gas bubbles and solids. I never really considered sound velocity as a technique but I stumbled across this years ago as I began to research. The technique I am using is more straightforward IMHO. Everyone needs to be aware that the unit I have cost about $500 when I total all the parts. I probably have $5000 in additional equipment for calibration. Sure I could do better on the parts with volume leveraging and lots of brainpower to streamline the design but I would be surprised if this thing ever becomes a $200 gadget. I have a full-time job and wife and kids so I don't get lots of time to play these days but I can assure you that I am pretty motivated to bring something to the table soon.

Ok...so what exactly are you doing to get this reading? Maybe I skipped over the explanation, but I was wondering and really interested.
Thanks

jmansfield, can you describe in more detail what exactly you're measuring to obtain these values, and what you're using to measure it?

I've been wondering if something like this would be possible the last couple of weeks.

I honestly have no idea what can be measured digitally that would give you the info you need, so I've been planning on doing something super simple as a start, just hooking up a USB thermometer to a small form factor pc, using something like --

Go!Temp, attach it to a tiny computer running linux connected with wireless...

They have other cool sensors available, maybe something like the CO2 sensor would give you some cool data... CO2 Gas Sensor

But yeah, sounds like what you're doing is way more sophisticated... Any guidance, hints?

Would be cool to end up with something like this eventually (but for fermentation) --
ThinkGeek :: DIY Plant Twitter Kit

Another interesting concept is doing this by weight. Essentially placing the carboy on a scale and keeping track of its weight. 20l of 12P wort that ferments down to 2P will loose about 0.816 kg of weight as the CO2 escapes. So if we can find a scale with a precision of +/- 5g at 30-40kg we can monitor the fermentation. Obviously this won&#8217;t work in case of a blow-off.

This has been suggested a while back.

Kai

My best idea is to submerge something buoyant (like a hydrometer) to a predetermined level and use a force sensor to monitor how buoyant it is.

I like the weight idea.

Coastarine said:

My best idea is to submerge something buoyant (like a hydrometer) to a predetermined level and use a force sensor to monitor how buoyant it is.

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The problem with that, and with keeping a hydrometer in the fermenter, is the affect that the kraeusen will have. It’s presence will skew the reading and when it cakes on it will drag down the hydrometer or the swimmer.

How expensive are scales that have a 0.01% error?

Kai

Kaiser said:

The problem with that, and with keeping a hydrometer in the fermentor, is the affect that the krausen will have. It&#8217;s presence will skew the reading and when it cakes on it will drag down the hydrometer or the swimmer.

How expensive are scales that have a 0.01% error?

Kai

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What if it you held something similar to a hydrometer (glass with air enclosed) submerged under the surface about halfway? It could be held down by a force transducer which is then connected to the laptop? This eliminates any problems caused by krausen, air bubbles stuck to hydrometer on surface, and the hydrometer hitting the sides of some kind of containment tube.

Parker36 said:

What if it you held something similar to a hydrometer (glass with air enclosed) submerged under the surface about halfway? It could be held down by a force transducer which is then connected to the laptop? This eliminates any problems caused by krausen, air bubbles stuck to hydrometer on surface, and the hydrometer hitting the sides of some kind of containment tube.

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I actually thought about that while I was typing the last response. The general problem with buoyancy measurements is, that the CO2 bubbles in solution will skew the results. Ever taken a hydrometer reading from a carbonated liquid? while there are bubbles still rising the hydrometer sinks in much further.

Kai

Kaiser said:

I actually thought about that while I was typing the last response. The general problem with buoyancy measurements is, that the CO2 bubbles in solution will skew the results. Ever taken a hydrometer reading from a carbonated liquid? while there are bubbles still rising the hydrometer sinks in much further.

Kai

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That occurred to me too. I'm going to think this over more, maybe have a double buoyancy thing going to cancel out this phenomena? i'm going to do some math.

The main problem with this solution is it is still going be fairly expensive. I ordered 4 force transducers for my lab last spring and was able to talk them down to $300 a pop, but maybe we won't need such hi-tech ones

How about measuring the pressure in an inverted tube? There was a recent thread about using a similar device as an automatic shut-off for filling a HLT. When the pressure corresponding to a particular volume is reached the water shuts off.

I found this at: Pressure/Density Level Instrumentation

By definition, specific gravity is the liquid's density divided by the density of pure water at 68° F at atmospheric pressure. A pressure gage or d/p cell can provide an indication of level (accurate to better than 1%) over wide ranges, as long as the density of the liquid is constant. When a d/p cell is used, it will cancel out the effects of barometric pressure variations because both the liquid in the tank and the low pressure side of the d/p cell are exposed to the pressure of the atmosphere (Figure 7-1B). Therefore, the d/p cell reading will represent the tank level.

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So then in theory, if the density changes, the d/p gauge will give an innacurate LEVEL reading, but if we know the volume is constant, then any changes in the gauge would be from changes in the liquids density.

I would think any CO2 bubbles would not be a problem as it should equilibrate with the whole vessel. I have no idea how sensitive such devices are. I was even wondering if one could rig up a low tech barometer as a possibility. Something as simple as putting a long thin clear tube through a carboy cap/stopper then sucking up some wort into the tube and then clamping the end so the liquid stays in the tube. The height should change as the density changes. The question is how long would it need to be to be sensitive enough to see the changes in density? Something like this. I don't think the vessel needs to be sealed as shown in the picture which would obviously not be compatible with a fermentor


I would think maybe that rather than inserting a d/p gauge into the wort, how about putting it at the top of the "barometer" like in the picture above. There could be a Tee at the top to allow the wort to be drawn up. This should magnify the pressure differences as the desity changes, increasing the effective sensitivity of the gauge (assuming a gauge stuck right into the wort might not be sensitive enough)

Here is a force plate for $210 that in sensitive mode can handle 800 N (180 lbs) and has a resolution of 0.3 N (1.08 oz).

Force Plate
Tech Info

I would buy one if it was <$100.

Man, I just read over post in this thread as fast as I could. This is epic cool. I admit it... I'm mildly aroused. That doesn't make me a bad person!

Just for anyone working on the weight method, 5 gallons of wort going from 1.060 to 1.010 will go from a weight of 44.228 lbs down to 42.142, losing just over 2 lbs. Seem right?

water being 8.345 lb/gal

Maybe someone makes a digital bathroom scale that could give good enough accuracy.

edit: Here's a scale for weighing pets that has a 44 lb capacity and half ounce resolution for 87.90. I don't like operating that close to max capacity but just an example of something that might work.

My problem with the weight method is what about trub? wouldnt that offset readings?

Here's how I was looking at it: weigh the empty fermenter with airlock, stopper, etc, and zero the scale. Put the wort in and get either a) an OG reading or b) an accurate volume. More likely that you'd have an OG, and you now have the weight of the wort, so you calculate the volume. From there it is a pretty easy calculation as the wort loses weight to assume a constant volume and calculate your new gravity. When you do a transfer, your gravity will stay the same and you'll have a new volume, then resume as usual.

And I just looked at the price of a refractometer and I thought they were way more expensive. I'm getting one and probably not worrying about this issue again.

This may just be me and my background, but I have no confidence in the weight change method.

Coastarine said:

Just for anyone working on the weight method, 5 gallons of wort going from 1.060 to 1.010 will go from a weight of 44.228 lbs down to 42.142, losing just over 2 lbs. Seem right?

water being 8.345 lb/gal

Maybe someone makes a digital bathroom scale that could give good enough accuracy.

edit: Here's a scale for weighing pets that has a 44 lb capacity and half ounce resolution for 87.90. I don't like operating that close to max capacity but just an example of something that might work.

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The Weight Max scale of 35# +/- .1oz, the 50# .2 +/- plus they have many other models available for higher weights plus a tare feature. Use a higher weight scale if you have a heavy glass carboy. The scale comes with battery and a 120 volt to 9 volt cube power supply. They can be repaired here in the USA if needed.
I believe I paid $13 for the 35# on ebay under "buy now" around 5 months ago. The company had the same and different models with different days of end of sale.

Well there seem to be about a hundred of these on ebay and they're going cheap:
65 lb scale

Parker36 said:

This may just be me and my background, but I have no confidence in the weight change method.

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Why is that?

I might be interested in the large postal scale. This would also allow me to weigh my grain all at once w/o the limitation of 4lb at a time.

Kai

Kaiser said:

Why is that?

I might be interested in the large postal scale. This would also allow me to weigh my grain all at once w/o the limitation of 4lb at a time.

Kai

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That's exactly what I figured, if weighing the fermenter doesn't work out I can still use it for that.

Coastarine said:

That's exactly what I figured, if weighing the fermenter doesn't work out I can still use it for that.

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+1 to being able to use the scale for a more practical use post experimenting.

I guess my big problem with the whole difference in weight thing is that the change is so small (less than .1lbs) over the course of the entire fermentation process, that there is no way you can get accurate readings. I just find that there are far too many variables and that this very indirect method of measuring fermentation wouldn't stand up. Sure, you may be able to get a good idea when it is finally done, but I wouldn't use it to measure a specific gravity or anything like that.

I would equate this method to using those body fat% machines that you stand on. They work indirectly by measuring the voltage that can pass through your body since fats, carbohydrates, and proteins all have different water contents. Does it give you a rough idea of where you are at? Sure. Would one ever be used in any kind of clinical study where the numbers really matter? Probably not.

I'm not trying to trample on the whole weight idea, maybe we are just looking for two different things.

I was thinking about what The Kaiser said earlier about CO2 in the liquid screwing with the buoyancy of a submerged hydrometer type thing and was wondering how this dissolved CO2 affects a standard hydrometer reading and how large the affect is.

Kaiser said:

Why is that?

I might be interested in the large postal scale. This would also allow me to weigh my grain all at once w/o the limitation of 4lb at a time.

Kai

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Coastarine; this might be of some intrest to you;

Besides the scale I posted above, have and enjoy is if you go to http://www. Amazon.com: Online Shopping for Electronics, Apparel, Computers, Books, DVDs & more, you'll have to ding around with the search section type in digital scales, yes a PITA. Check out the Maxweight 75 lb Digital Postal Scale they have a 75# for your grain weighing plus it's "Readability" is .2 oz / 5g. Price $28.99. This is before shipping and like the 35# Maxweight I posted above it comes with a 9 volt battery and a cube 120 volt power supply. This 75 pounder would handle those glass carbo tare weight plus contents that was mentioned before. Weightmax even have repair facilities here in the states not shipped out of country. Like everything else it's made in China that's what's on the box of my Maxweight 35#, +/- .1 oz accuracy scale.
In the future the US of A may become the US of C? Just a thought after walking thru Walgreens reading lables on everything waiting for a prescription order. Home Depot's Irwin (a US manufacture) the magnetic tip extensions are made in China. Not a rant here just what I have seen now back to the scales.

I got one of the 76lb .2oz resolution ebay scales. Some of them are free shipping and the bidding usually ends at 25. The one I got was 14.95 shipping and I got it for 9.95 making my total 24.90. If it isn't a piece of crap then that's a good deal to me.

Coastarine said:

I got one of the 76lb .2oz resolution ebay scales. Some of them are free shipping and the bidding usually ends at 25. The one I got was 14.95 shipping and I got it for 9.95 making my total 24.90. If it isn't a piece of crap then that's a good deal to me.

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You'll need to run some experiments for us once you have it. Like put a full carboy and a cup of water on and see how accurate the weight changes as you remove tsps (5 g each) of water.

I ran the concept through a spreadsheet last night and found that every 10g loss equates to rougly a 0.1 Plato (~ 0.4 gravity points) drop in a 5 gal batch. This is better than my standard hydrometer. Apparently there are cheap enough scales that can do that.

But if the Scale doesn't stay on all the time you'll need to lift the carboy/bucket and tarre the scale. That might be annoying. If it was to stay on we have to worry if it would drift out of calibration.

Ideally I'd like to use a cheap scale (or the force plate that was listed although it is rather , hook into the logic to get the sensor reading and connect this to a small computer with display. Not sure how much these computers would cost. Then write a program that allows you to record the weight, enter the OG and allow for sampling or Kraeusen skimming which removed mass that doesn't correspond to a SG change. if the overflow bottle/bucket for blow-offs are on the same scale, that system would also work if a blow-off tube has been rigged.

One caveat I know of is that this measurement is indirect by measuring the amount (i.e. weight) of CO2 that escaped from the fermentation. I would have to find out through experiments if the slight supersaturation (more CO2 in solution than there should be at equilibrium) makes a big enough difference that it matters.

If it could be build for less than $150 I'd be up for it. Most of the parts would be reusable for other tasks anyway.

Kai

I also thought about leaving the carboy on the scale and even if it was turned off I think the constant strain could be bad for it, so here's the plan:

I'm going to just have a simple excel spreadsheet. I'll weigh the better bottle and any blowoff rig, enter that into the spreadsheet. I'll use my hydrometer (or refractometer if I have one by then) to take an OG. This will give me a weight like I was talking about earlier. I'll weigh it periodically, and when fermentation is well over I'll take another gravity with the hydrometer, and we'll see how accurate this is.

As far as the dissolved CO2, I think it will be very consistent and easy to compensate for. Naturally the volume and temp of the beer decides how much CO2 stays, and that should be almost exactly the same from batch to batch, or easy calculated.