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.
