I'm currently trying to figure out a cheap way to build a cocktail machine. For now the machine should have about 20-30 possible input liquids. These liquids should remain in their original bottle and should electrically be pumped up when needed. (I know I could use gravity instead of pumps, but the bottles should be stored in a cabinet under the machine itself.)

At first I was looking for a good type of pump to use for this project and I think peristaltic pumps would be ideal because then I could be sure that the liquids haven't come in contact with anything but the hose.

Then I tried to find the cheapest pumps of this type available, but unfortunately the cheap ones are still about 5€ and they would only do 150ml/min. I think 500ml/min would be the absolute minimum required.

But now I'm thinking that maybe there is a cheaper way and I just don't know the components.

So my idea would be that maybe I could just buy one big pump (maybe something like this) and then connect all 20-30 hoses to it using a bunch of adapters (maybe a bunch of these). Then I would just need cheap way to electrically close all but one hose at a time. So I was wondering if there if some sort of electric valve that is very cheap (maybe 1-2€) and doesn't come into direct contact with the liquid. I was thinking maybe some sort of electromagnet that squishes the hose or a DC motor that uses some sort of screw mechanism to bend the hose until nothing can pass through anymore. I should also mention that I'm going to use something like an ESP8266 or maybe an Arduino to control the whole machine.

Is there any such component?

Edit: As suggested in the comments it might be a better idea to simply pump air into the bottles to get the liquid out. This way I can run completely separated hoses avoiding the problem that liquids may flow back into the wrong bottle (which would especially suck for milk and cream etc.). I found really cheap air valves that I could use for this purpose. I could power/control them using a relay board like this which I'd attach to an Arduino. Then I'd then just connect a compressor or CO2 container at a reasonable pressure to the valve input. Sounds like this could work to me. But what if these valves aren't perfectly clean? I should probably have some sort of air filter behind each of these, right? Any ideas how I could accomplish that in a cheap way?

I have intention of using this machine commercially btw.

Edit2: Another problem with the air idea is that I'd have to buy a compressor for that. And they are loud and expensive form what I can tell and besides that they are completely overkill. I doubt I'd even need a 1 bar of pressure. Is there maybe some sort of cheap low power (but therefore very quiet) compressor that I could use?

Edit3: Could I build an air filter like this one but instead of using a PVC tube, simply use the hoses that go into the bottles?

Edit4: Bottles that are carbonated in the first place could be another challenge because they would just push out liquid automatically over time unless I build a mechanism that detaches the compressor and then opens all valves that that no bottle can build up pressure while the machine is idling.

Edit5: Maybe a quiet fish tank air pump could be used instead of a compressor. I found some that are rated: throughput: 192 liters / hour power: 2 watts pressure (MPa): >0.012 noise: < 40 db

I think 0.012 MPa would be 0.12 bars or 1.74 psi. But I have no understanding of how much that actually is and if it would be enough.

  • 3
    $\begingroup$ This question is about shopping for electrically actuated valves. The suitability appears to be determined by price and the suitability for use with liquids for human consumption. This is not an electrical engineering design or theory question. Voting to close. $\endgroup$
    – user6431
    Commented Jan 10, 2020 at 16:18
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    $\begingroup$ The concept for pressurizing the liquids so that that the selected one flows when the related valve is open may need further development, but that is not an electrical problem either. $\endgroup$
    – user6431
    Commented Jan 10, 2020 at 16:22
  • 1
    $\begingroup$ Cross contamination and purging are an issue. Voting closure. $\endgroup$
    – Andy aka
    Commented Jan 10, 2020 at 16:38
  • $\begingroup$ I agree consider CO2 tank pressure regulator to suitable tanks $\endgroup$ Commented Jan 10, 2020 at 16:40
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    $\begingroup$ Not only that, but this brings with it a whole host of biological concerns. How long is grenadine, lets say, going to "be good" and "taste alright" in a valve? What happens when it spoils, unbeknownst to the operator, and multiple people get sick? I see a long road of legal battles a possibility. $\endgroup$
    – rdtsc
    Commented Jan 10, 2020 at 16:42


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