Is there a way to measure Keg full level?

Like the topic states, is there any (hopefully easy/cheap) way to measure the level of beer in a keg (corny or otherwise)? Preferably in some way where an electronics part could do the job.

Here's one cheap and easy method
http://www.micromatic.com/part-pid-SS100.html

Otherwise maybe there is something that could count the ounces poured at the tap?
Or a some kind of scale and warning system that could just keg volume by weight?

Yes, weigh the keg. I use a digital bathroom scale for this. Weigh an empty keg to get the tare weight and subtract that from whatever the partially filled keg weighs. Divide the net weight by 8.4 (water is 8.34 lbs/gallon, so I'm guessing the beer is about 1% heavier) to convert to gallons. You can also use a remote read infra-red thermometer. Shoot the side of a cold keg and you can find the beer level by detecting a sharp temp differential between the head space and the beer. This will give you an approximate indication, but that's usually good enough. You can also weigh propane tanks the same way to see how much gas you have remaining.

Cheapest way I can think of is leave a cold keg in warm air temps for a couple minutes. Check condensation on keg. Voila.

Hmm, I'm looking for a more automated way to do this (i.e. report to a microcontroller, etc). Kind of like a KegMeter, but I'm not planning something as sophisticated as that.

Jublin said:

Hmm, I'm looking for a more automated way to do this (i.e. report to a microcontroller, etc). Kind of like a KegMeter, but I'm not planning something as sophisticated as that.

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I'm curious as to why you want to go to all that trouble and expense simply to determine how full the kegs are. I can lift a keg and tell about how much is in it. I can also easily determine when a keg is empty. No more beer comes out.

Because I want to do something for a kegerator build (LED's, etc. I'm an embedded software dev) this summer. If it's not cheaply feasible (force sensors on digikey are ~30-50 a pop), I'm not going to do it.

Basically just a feeler. I'll probably just buy the strips if I can't figure something out.

I can seethe benefit of something like this as well. I've got six kegs in my fridge, and so three are behind the others.

I also replaced the door with a wood insulated face, so it's not something I like to keep pulling off to check volumes.

I currently just tap them until I get CO2 spitting out. It would be cool if I could get a little more notice that somethings getting low.

+1 on the strips. I'm going to look into thatmyself.

Catt22 said:

Yes, weigh the keg. I use a digital bathroom scale for this. Weigh an empty keg to get the tare weight and subtract that from whatever the partially filled keg weighs. Divide the net weight by 8.4 (water is 8.34 lbs/gallon, so I'm guessing the beer is about 1% heavier) to convert to gallons. You can also use a remote read infra-red thermometer. Shoot the side of a cold keg and you can find the beer level by detecting a sharp temp differential between the head space and the beer. This will give you an approximate indication, but that's usually good enough. You can also weigh propane tanks the same way to see how much gas you have remaining.

Click to expand...

This is the way I was planning on measuring the remaining volume and % remaining. You can calculate the density of the beer using the final gravity.

For example:

At 38 degrees F the density of water is 8.345 lb/gal. Specific gravity is the ratio of the densities so if the final gravity of the beer is 1.011, at 38 degrees F the beer would weight is 8.437 lb/gal. Therefore, 5 gallons of beer would weight 42.185 pounds plus the empty weight of the keg.

I saw one using load cells - can't seem to find the write up right now, but it actually "reported" out - I think by email; when the keg needed to be changed.

If you're in the software side - this would probably be a sweet set-up!

rack04 said:

This is the way I was planning on measuring the remaining volume and % remaining. You can calculate the density of the beer using the final gravity.

For example:

At 38 degrees F the density of water is 8.345 lb/gal. Specific gravity is the ratio of the densities so if the final gravity of the beer is 1.011, at 38 degrees F the beer would weight is 8.437 lb/gal. Therefore, 5 gallons of beer would weight 42.185 pounds plus the empty weight of the keg.

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Yeah, I think your right. My 8.4 lbs/gallon estimate would be way off by something like 0.037 lbs/gallon on the light side. That's more than 1/2 oz of beer! Probably doesn't matter anyway though, as my bathroom scale only has resolution to 1/10th of a lb.

Never said your way would be way off. I was just over engineering it.

Try these force sensors http://www.trossenrobotics.com/flexiforce-100lb-resistive-force-sensor.aspx, they are more reasonably priced.

maybe a float sensor like in gas tanks? not sure how difficult it would be to keep it sterile. you'd also need to be able to transmit the signal wirelessly.

I been using the keg strips for a while now. They work pretty good for the money.

Why in the heck don't you just use a float switch in each keg?

Take 5-6 beers (water really) and dump them in the keg (or however many you want it to warn you at) and just use that as a measure for knowing when the level of a keg gets to that many beers. You could even install two of them per keg to warn you at 1/2 level and 5-6 left or whatever you want.


BTW, those strips that everyone else posted suck. I have them on my kegs and it is kind of annoying having to use a warm rag every time. I would certainly use them over nothing but if there is a better way then I would use that.

kladue said:

Try these force sensors http://www.trossenrobotics.com/flexiforce-100lb-resistive-force-sensor.aspx, they are more reasonably priced.

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+1 think that this would work need a plate to make sure that position of keg is always on sensor

Use a 25 Lb sensor and a triangular base for the keg, 2 fixed points and force sensor under 3rd point for measurement. A 1/2" piece of plywood, 2 - 1/4" X 1-1/2" round head bolts nuts and washers for adjustable non measuring side pivots and leveling, chair leg cap to set on force sensor for third point, and some 1/4" X 1" dowels to make a ring to center keg each time. If this were setup on a piece of plywood that fit the bottom of a keezer, match the pivot bolts with stationary bolts in the base plywood and use a vinyl hose sleeve to keep platform pivots from moving around, you could build a multiple keg system fairly cheaply.

If you want something automated then load cells and/or flow meters are the way to go. Both of those are easily accessible and shouldn't be too complicated or expensive ($100-200) for a set up. Check out this site for some great examples including quite a few part lists.

http://kegbot.org/

With the load cells you will need to make sure that the load is distributed evenly, which is why scales typically use four sensors, one on each leg. If going the load cell route just research micro controlled scales, there is a ton of information. If going the flow meter route look into some computer over clocking sites, that is probably the most common non commercial use.

I'll be going this route once I run out of other projects, post back with updates.

Hack-a-Day had one awhile back.

brew more then it won't matter if you run out...

fuhmon said:

brew more then it won't matter if you run out...

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Until I have more money (kegerator is going to drain my budget in and of itself), this'll have to be the way I go for a little bit . However, the kegbot/other links are exactly what I was looking for! I was just thinking simple 1/8 step (or 1/10th step) LED's, but the arduino-based kegbot is pretty awesome, and very doable in the long run.

I need to stop reading those blogs, haha. It's giving me a lot of ideas.

the flow sensor idea is probably going to be the easiest to impliment. the cheapest food grade flow sensors i had found are about $25 each, and they are from a UK company. you can find them on ebay sometimes. for 6-8 taps, thats going to be a chunk of change....

i like the tripod and force sensor idea. you can easily extrapolate the weight of the keg from measuring one foot of the tripod. either of these methods would hook up to a controller like an arduino or stamp or something fairly easily.

another option, though probably more complicated then its worth, is to do pressure differential measurments to find the empty volume in the keg. if you have a know volume of gas and inject it into an unknown volume of empty space, you can measure the pressure increase of that empty space and determine its volume. you would need a few different sensors on each keg though... just an idea.

Look Here for information. It can get a bit expensive though.
http://www.omega.com/prodinfo/flowmeters.html

While the flow measurement option is viable, the more connections made in the product lines, the greater the potential for infection sources to develop. The force sensor is outside of the sanitized system and is fairly simple to calibrate, empty keg for tare weight, full keg for maximum sensor output scale, scale factor derived from measured range divided by ounces/pints volume in full keg.

This is cool..
http://www.beercooler.com/suds-counter.html

http://www.keg-meter.com/

Ebay, Amazon, micromatic, etc has smartstrips for $4-$6, but shipping is between $12-$18. Really, why? I only want three and it comes out to $30ish.

Anybody know any reasonably priced vendors for this item?

your first post is on a 2 year old thread complaining about shipping? really?

Yep, REALLY...the item probably weighs less than an ounce. You don't think $18 for shipping is a ripoff?

If you're still looking for a cheap, effective, accurate and simple continuous keg level indicator, check out this site.

www.ballandkeg.com