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Simple automated spunding valve

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sounddoc

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I've got the BrewPi set up now (I'm using dotps1's Arduino uno / Raspberry pi build) and I'm now hooked on microcontrollers. I'm going to go down this route unless there's a better option in designing a spunding valve that can be tied into the version of brewpi that I'm using (former web developer here).

So far I have these two bits to start with:

Obviously a 2nd Ardiuno will have to join the family (can't have too many, I'm finding).

Opinions? Other pieces of hardware (other than plumbing) that I'd need? It would be my first 'from scratch' Arduino project.
Thanks!
 
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sounddoc

sounddoc

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I should also note if possible I don’t mind tying this directly to the pi too.
 

Vale71

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Make sure the valve vents through as small as possible a pinhole otherwise with the combined hysteresis you might find your system constantly undershooting the set point.
 
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sounddoc

sounddoc

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Make sure the valve vents through as small as possible a pinhole otherwise with the combined hysteresis you might find your system constantly undershooting the set point.
Is there a source I could learn about with this? I'm not familiar, but I do appreciate the opportunity to learn!
 
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sounddoc

sounddoc

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Ah I get it. Dumping the pressure when it hits a target means it’ll continue and the transducer won’t reliably read a value where it should close the valve back up. I wonder if a timed release would help, instead of dump until it hits the target, dump for a few seconds, close then check, rinse and repeat.

it’ll make more sense once I have a test circuit with the hardware set up. Thanks all!
 

day_trippr

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It is an input change rate verses response time issue. Using a very tiny orifice on your solenoid valve would better allow the sensor - and full feed back loop - to hold a target pressure.

A similar paradigm is using a 1000 watt hair drier as the heating element in a small fermentation chamber. By the time the controller can react the overshoot is massive...

Cheers!
 

moorejl57

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I had made a software based pressure regulator for a work project years ago to control a 2000 psi pressure chamber using a PLC. The designer had spec'd a $1500 mechanical regulator that performed very erratically and had a large hysteresis. I removed the regulator and made use of the pressure sensor already present on the system along with a fuzzy logic controller that kept the pressure within 20 psi of target. It did employ small orifices to both fill and bleed the pressure in the chamber.
 

pocketmon

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I implemented pressure control in BrewPiLess. However, my hardware building skill sucks and I haven't run it in real life.
Some people do report working, though.
 
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