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-   -   keg ultrasonic liquid level sensor. (http://www.homebrewtalk.com/f51/keg-ultrasonic-liquid-level-sensor-370496/)

techbrewie 11-27-2012 09:54 PM

keg ultrasonic liquid level sensor.
 
Hey all I had an idea I wanted to bounce off you regarding measuring keg volume electronically and reporting it to a controller. The three solutions that exist:

1). weight sensors.
2). flow sensors.
3). Sensing tap handle pulls and counting seconds pouring to calculate volume used using flow rate.

I'm going to buy a keg lid to experiment with. drill a small hole in the top through which I will run my wires. Attached to the bottom of the lid will be a ultrasonic sensor that would measure the exact distanct from the sensor to the liquid. Using that measurement and the exact dimensions inside the keg, I could accurately and continuously measure the exact liquid volume in the keg. my two concerns are

a). pressurizing effects on electrical components and the ultrasonic sensor. even though its a relatively low pressure i think it still deserves some consideration.

b). ability to re seal the keg to at least hold enough pressure to serve beer. (i could force carb and condition with normal keg lids).

the beauty of this idea is that the only modification is to an easily replaceable 10$ keg lid rather than messing with your beer lines, tap handles, kegerator etc. what do you guys think?

jpalarchio 11-28-2012 01:09 AM

Do you have a link to the sensor you're looking at using?

aphid_rancher 11-28-2012 04:52 AM

JB weld will seal the hole up well enough to hold pressure. You will want to pot your circuit to make it submersible and may want to worry about doing it in a food safe way. There are food safe adhesives and sealants available. Interesting idea.

day_trippr 11-28-2012 05:04 AM

Surprising that c) ability to withstand a hostile acidic fluid without contaminating same wasn't included in the list ;)

I think it would be cool to pull something off along this idea, especially if you could design the device that manipulates the transducers to support, say, six keg sensors (<= the fact that I have a six faucet keezer has absolutely nothing to do with that! ;) )

I'll definitely be following this thread. Hope it's a fruitful one!

Cheers! :mug:

mrstevenund 11-29-2012 01:59 AM

I had the same idea, just am going about it differently. I'm doing the flow sensor method. I didn't want to deal with resealing the keg with wires coming out. And most weight sensors are not rated for continuous pressure (start to drift over time). Easiest solution for me is to use swivel nuts to seeedstudio.com's G1/2 flow sensor.

techbrewie 11-29-2012 03:27 AM

steven,
Flow sensors are the next best thing. They can measure flow to an acceptable degree of accuracy, however i have been looking for a way to get exact measurements because i am a little bit anal :P
You could either do this with an ultrasonic sensor or an infrared sensor. Infrared would be much easier to do, but im not 100% on the effects of infrared light on beer, even though it carries less energy than visible light. any thoughts on that would be helpful.

JB weld is an interesting idea, and wouldn't make contact with the beer, so as long as it doesn't release any airborne chemicals that would be the way to do it.

The unique part of this idea is that it would be exact in its measurements from what I understand this is unprecedented. Another idea may be to solder the gap shut, cover with jb weld on the outside? i may just have to pick up a lid and experiment. I guess.

BetterSense 11-29-2012 03:45 AM

IR will not hurt the beer. Besides, there's no reason you couldn't leave the IR off 99% of the time and just take sample measurements.

I have a feeling ultrasound won't work inside a keg due to echos.

techbrewie 11-29-2012 03:49 AM

so after some research it seems that jb weld after being cured is non toxic, and should leech any off flavors into the air. ordering up a keg top, wont get the sensor up and running yet. but ill put it together and pressurize with my Graff hoping for the best. *fingers crossed*

techbrewie 11-29-2012 04:04 AM

so it looks like I am going with an IR sensor sealing the top with JB weld. Endgame would be to program each IR sensor to read from its respective keg after each pour. (i have separate reed switch sensors to detect when a handle is pulled.) the only issure i can forsee is with the stout kegs running at 30 psi. unless you guys think the jb will hold.

BetterSense 11-29-2012 02:58 PM

You can't tell anything based on the pressure alone. The other very important factor is how much area your sensor takes up. At 30psi, if you drill 1 square-inch hole in your keg top (~1 1/8" diameter), your JB weld is going to have to hold 30 pounds of force. If you only have a 1/8" diameter hole, the force on the sensor is only 6 ounces.

I would just program the sensors to read every hour or minute or day or something. Or every 10 seconds if you want to. Why bother with reed switches?


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