CO2 Leak Sensor for Kegerators - Good idea?

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megabyte

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Tonight I removed a gas hose from one of my corny kegs and noticed the post hadn't been screwed down tightly. I haven't lost all my CO2 this time, but I have wasted a lot of CO2 in the past with other leaks. Sometimes when I store a keg I find it flat a few weeks later because the poppets didn't seat correctly. Other times the main o-ring doesn't seal and my CO2 tank goes flat ahead of schedule. This latest incident was entirely avoidable, I just forgot to tighten the posts after cleaning and assembling my keg.

Tonight I wonder - has anyone DIY'd a CO2 sensor for their kegerator? I'm thinking: CO2 Sensor + Arduino + Buzzer + Display. Just mount it inside the kegerator near the bottom where CO2 would gather if there were a leak. If the buzzer sounds, that's when you'd know to break out the sprayer of detergent to look for a leak.

Before I embark on yet another epic DIY adventure I thought I'd check to see if anyone's tried this before. Any suggestions? Reasons it won't work? Reason's it's pointless? Better ideas?
 

quadbox

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I havent done one on a home system, but a co2 sensor's pretty much a requirement for any commercial draught system for OH&S reasons. a 22kg co2 bottle with a significant undetected leak can quite easily suffocate people.
 

nosco

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I'd love one! I've lost a few bottles due to various leaks but mostly due to the dodgey valves on my manifold.
 

mxd

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I'm sure there is one mentioned somewhere in here I don't remember when who etc..
 

GibboQLD

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Michael Burton said:
has anyone DIY'd a CO2 sensor for their kegerator? I'm thinking: CO2 Sensor + Arduino + Buzzer + Display. Just mount it inside the kegerator near the bottom where CO2 would gather if there were a leak.
Would be a better idea to mount the Arduino outside and the sensor inside, just in case you ever get a liquid leak / massive build up of condensation.

You could also add an ESP8266 to it and use something like grovestreams / twitter + IFTTT to send alerts to your phone if it happens when you're not home.
 

DJ_L3ThAL

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I looked into this, there is a small PCB mount type infrared sensor from Jaycar. I'll dig up details when I get a chance and post them here. Never though of using Arduino for it I was thinking of building my own circuit but wasn't up for the challenge. Arduino should be quite simple. The sensors don't last forever, so would be interested to see how often they'd need replacing. At work we replace co2 cells between every year up to 5 years depending on manufacturer.
 

professional_drunk

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I don't have a leak but neither do I willingly breathe the air inside my keezer when I'm cleaning the bottom. Wouldn't you get false alarms from that?
 

megabyte

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GibboQLD said:
Would be a better idea to mount the Arduino outside and the sensor inside, just in case you ever get a liquid leak / massive build up of condensation.

You could also add an ESP8266 to it and use something like grovestreams / twitter + IFTTT to send alerts to your phone if it happens when you're not home.
Good points. I'm thinking of doing a replacement control panel for my kegerator with WiFi awesomeness so a CO2 sensor could probably tie into that if the long signal lines aren't too susceptible to interference.

DJ_L3ThAL said:
I looked into this, there is a small PCB mount type infrared sensor from Jaycar. I'll dig up details when I get a chance and post them here. Never though of using Arduino for it I was thinking of building my own circuit but wasn't up for the challenge. Arduino should be quite simple. The sensors don't last forever, so would be interested to see how often they'd need replacing. At work we replace co2 cells between every year up to 5 years depending on manufacturer.
I can't seem to find them at Jaycar so a link would be great if you can find them,
EDIT: Found them here at Jaycar. AUD$30 is pretty good too!
they sell them at futurlec for about USD$35. The datasheet says they last for 5 years but I wonder if you turn them off and on a lot it it can extend their life, or shorten it drastically like an incandescent light globe. Also I worry about how condensation could affect them.

professional_drunk said:
I don't have a leak but neither do I willingly breathe the air inside my keezer when I'm cleaning the bottom. Wouldn't you get false alarms from that?
Good point, Keezers do tend to trap CO2 so it could be a pain to clear the CO2 away after a leak is solved. This might make the project inappropriate for keezers which is a shame. I use one of the KegKing/Craftbrewer/Alibaba Chinese style kegerators with a door on the front so shouldn't be a problem personally, but it's a good point and something to think about.
 

GibboQLD

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Michael Burton said:
I'm thinking of doing a replacement control panel for my kegerator with WiFi awesomeness so a CO2 sensor could probably tie into that if the long signal lines aren't too susceptible to interference.
Nice! That'd definitely do the trick. Going to implement something like Kegerface or similar?

Michael Burton said:
EDIT: Found them here at Jaycar. AUD$30 is pretty good too!
Don't forget you'll need a boost converter to get a steady 6V for the internal heater, plus some kind of amplifier to translate the 0-50mV signal to something the Arduino can read with more accuracy.

Little Bird have an all-in-one product that includes the sensor and does all of the above with only 3 pins (Vcc, Sig, Gnd), but at almost $90 before shipping, you're almost certain to find a cheaper version elsewhere.
 

peteru

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The 1.2W @ 6V required for the heater is a pain to work with. If you are generating that much heat in the fridge, you are not going to have issues with condensation on the sensor itself, but your fridge will have to work a bit harder. My guess would be that cycling the sensor too often is not really workable. You want it running permanently so that the heater stabilises. Presumably the wear and tear due to thermal instability caused by turning the sensor on and off too often would reduce the service life.

If you are building something with this sensor, you might as well add at least a temperature sensor so you can compensate for the temperature drift. Maybe humidity sensor too, if it's not too expensive.

If you are looking for sensor alternatives, check out the ST web site. They have all sorts of cool sensors, including a bunch of MEMS "toys". EDIT: I looked at ST site, but could not find anything suitable.
 

megabyte

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GibboQLD said:
Nice! That'd definitely do the trick. Going to implement something like Kegerface or similar?
Re: Keggerface/Raspberrypints/taplist.io - Actually that's a separate project we've been working on commercially that's scheduled to launch on Kickstarter in October if all goes to plan. The kegerator control panel idea is basically a replacement PCB like what Kegking sells, but with WiFi, font fan control, stepped fermentation profiles etc. and there are no plans to commercialise that, it's just a DIY project. Same goes for this CO2 alarm idea, it's more just for DIY fun :)


GibboQLD said:
Don't forget you'll need a boost converter to get a steady 6V for the internal heater, plus some kind of amplifier to translate the 0-50mV signal to something the Arduino can read with more accuracy.
Good points, I'll keep these in mind. Thanks!

peteru said:
The 1.2W @ 6V required for the heater is a pain to work with. If you are generating that much heat in the fridge, you are not going to have issues with condensation on the sensor itself, but your fridge will have to work a bit harder. My guess would be that cycling the sensor too often is not really workable. You want it running permanently so that the heater stabilises. Presumably the wear and tear due to thermal instability caused by turning the sensor on and off too often would reduce the service life.

If you are building something with this sensor, you might as well add at least a temperature sensor so you can compensate for the temperature drift. Maybe humidity sensor too, if it's not too expensive.
Wow I didn't realise the CO2 sensors draw so much power until you posted this. 1.2W in the fridge is a concern, but I just checked and found that the circulation fan that came with my (series 1) kegerator is rated at exactly 1.2 watts too. I guess the fridge will have to take one more for the team :unsure:
 

peteru

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You could go for one of the more expensive infrared based CO2 sensors. CO2 Meter - COZIR Ambient CO2 + RH/T Sensor - CO2 Sensor by GSS is a pretty awesome piece of kit. Not cheap, but all you need to do is hook it up to something with a 3.3V TTL serial port and make decisions based on what it reports. Those sensors draw bugger all power and are smallish. The manual for that piece of gear is one of the best ones I've seen for a long time.
 

megabyte

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I've been looking at some infrared types for about the $40 mark here and they do tend to use less power. They are still limited with a 5 year life span surprisingly, but since they use light and not a chemical reaction I expect they will just lose sensitivity gracefully as the internal LED wears. From the photos the sensors appear to have in-built signal conditioning circuitry and an STM32 microcontroller so you sure get a lot with your $40 sensor.
 

peteru

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There's no decent info on the AliExpress page to be sure, but I think it may be mislabelled. The back of the board shows a pinout for a connector that is very much like the heater based electrochemical sensors. The size of the metal casing also suggests it may not be IR.
 

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