Force Transducers to measure Volume

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jgalati

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Has anyone successfully used a force transducer to measure the weight of a kettle as a way of calculating volume? Obviously it gets a little complicated when you have water in the piping and pumps of an electric brewery, but ignoring that, has this been done? Can't seem to find any threads on it.

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I think you would need to find a way to isolate it from the heat.
 
Sounds like an overcomplex solution. couldn't you just use a simple two wire sensor where the liquid makes the contact?

or if you're looking to measure varying levels a simple float sensor should work.
 
Sounds like an overcomplex solution. couldn't you just use a simple two wire sensor where the liquid makes the contact?

or if you're looking to measure varying levels a simple float sensor should work.

My solution is even simpler - I mounted a mirror above my hot liquor tank at an angle so that I can see when to shut-off the water.
 
I'm working on a mostly autonomous brewery besides dough in and hop additions. Right now water volume is killing me lol.

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I'm working on a mostly autonomous brewery besides dough in and hop additions. Right now water volume is killing me lol.

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If you are always starting with the same volume then some sort of float switch should work. It would be inside the pot and away from direct heat.
 
A google search returns several possibilities. There are optical, ultrasonic, capacitive, and a host of other styles.

It's a common problem in manufacturing, you shouldn't have any problem finding something that works, but it's likely to be expensive.

Search for liquid level sensor, or non contact liquid level sensor.

Good luck.
 
The problem I see with many of the methods is that the density of the liquid changes (specific gravity) and thus weight, pressure due to height, even capacitance changes as gravity changes.

On my brew troller setup I use the back pressure from the bottom of the vessel with air flowing through it to compensate for temperature (aquarium pump) and measure the pressure at different heights. But the gravity of the wort changes this equivalent height to volume because the density changes. I did the math on the brew troller forums and at a 1.090 gravity the volume in a keg with 12 gallons of wart in it (preboil volume) is off by 0.8 gallons.... that's non trivial. So I wrote code into the brew troller to modify the pressure reading based on the pre-boil gravity, luckily because its unitless and already a ratio, you can just divide the pressure reading by the gravity (in 1.XXX form) to get the actual pressure water would great at that volume. Thus if you calibrate with water you're all set.

Doing the above modification to the setup has now had me get with in 0.1 of a gallon every brew no matter the gravity. This is still off like it is because the pre-boil gravity is not exactly the same every time as the efficiency changes with the variations in the grain year to year, among other things, but it made it much more accurate.
 
1/10 of a gallon is 12.8 oz. Seems like a lot. Is this an example of something that just doesn't lend itself to automation? Is that for a 12 gallon brew?

This would be .8%, the equivalent of the difference between 1.030 and 1.039. kind of a wide variance if you are a numbers person.

I don't understand your concept. Does your formula take into account the barometric pressure?
 
I get a bit closer with a wet sensor and formulas that factor density with grain weight and density,temperature, and extraction over time in mash tun. For boil kettle it is estimated SG, temperature, and evaporation rate to reach FG. With a wet sensor the barometric pressure is not a factor, with bubblers it might be if the sensor and analog input resolution is sufficient.
As far as I know I have not seen any successful load cell equipped brew systems, much to complex electronics to implement for process control.
I do load cell equipped tanks on occasion so I do know what is needed to setup a weighing system for process control.
 
Had that thought but I haven't found a reasonably priced food grade and temp gradeeter which fits the bill. I'm definitely going to use the bubbler method and I'll post pseudocode on how I took temp and gravity into effect

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The sensor I use compensates for local pressure because it has an inlet that DC biases the sensors output based on the pressure it reads, so in reality its 2 pressure sensors. 1 to measure ambient pressure and modify the DC level of the sensors output, and then the actual pressure sensor used to measure the pressure of the "depth". Its the default sensor the brew troller guys tell you to use, works great.

As far as the 1/10 of a gallon that number includes variances in gravity due to change in efficiency. If you know exactly what your gravity is then its accurate to within .002 gallons.

And yes, its a 12 gallon preboil for a 10 gallon batch.

As far as flow rate, I found a set of turbine based flow meters for only 40 bucks a pop, they gave a pulsed output that you could count over time to get a flow rate. The issue was that if you get a larger turbine (larger diameter) the price goes up fast, and they become harder to count (lower rpm for same flow rate), but if they are smaller diameter (these were 3/8 inch ID) I've had issues with them clogging due to all the stuff that is in wort. Thus I just went with the change in volume over change in time. I'd love to have a capacitance drive or ultrasonic type flow meter but they are just so damned expensive.


So the bubbler that the brew troller guys (and I) use compensates for local pressure, and temperature, then you have to give it your estimated pre-boil gravity to have it compensate for gravity ( I wrote that code for them, I believe they put it into the open source code base). I went through a crap ton of math just to show that you can just take the ADC value from the pressure sensor and just divide it by the gravity and it compensates for the change in pressure due to change in density.... all that work just to prove the fix was so simple.

I'll also warn you that with the bubbler the voltage output from the sensors is very noisy, I had to put a low pass filter in between the sensor and the ADC as well as use a 32 sample average with a 20ms sample time to get it to work so well.
 
Amazing how complex this automated liquid level sensing tech is. . . so many variables to consider. Makes reading temp seem trivial by comparison.

What about a cheap float valve? Anyone found one that can be read as a single 0 vs 12V (on/off)? I'm thinking of installing something simple on my rig to protect my BK elements from level drop when I'm mashing in.
 
What about a cheap float valve? Anyone found one that can be read as a single 0 vs 12V (on/off)? I'm thinking of installing something simple on my rig to protect my BK elements from level drop when I'm mashing in.


Like this?

https://www.oscsys.com/store/product/Stainless-Float-Switch

There others out there as well with more of a ball type float on either a vertical rod or a vertical rod with a 90 degree at the top.
 
The wet transmitters I use are older Heise 621's with 0-2PSI span, 4-20 MA output, connected to an Opto 22 AD3T module. The level transmitter spans were tweaked to reduce span to 0-35" WC, (limit of span pot). The level transmitters are mounted below sensing connection, and far enough away to avoid heat effects from boil kettle burner. Here is a construction picture of the panels,https://picasaweb.google.com/110297595278760536729/Phase2BrewingPanel?noredirect=1#5144799706307697042 pressure transmitters are gray cylinders on upper right side of right hand panel, below is differential pressure transmitter for FB pressure drop, above is red mass flow controller for boil kettle gas flow control.
 
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