-1
$\begingroup$

I am making a "bar bot" and I am trying to figure out a way to dispense soda without it going flat. I am using a bunch of peristaltic pumps:

pump gif

Which luckily remain sealed at rest. I was thinking of drilling a hole in my soda cap and hot gluing a pipe barb so I could pump soda from the sealed container. I realize that without replacing the dispensed liquid with an equal amount of air, this will slowly create a vacuum in the bottle which will become a problem eventually (I imagine the bottle will start collapsing in on itself). I think I should be solving an issue like this with some sort of valve, but what type?

I am looking for something very small and cheap that will remain sealed at rest (don't want the soda going flat). I only want the valve to open when the pressure in the bottle drops below atmospheric. MOST importantly I am looking for a valve that does this automatically. If I need to fiddle with it manually, I would just uncap the bottle myself every once in a while. There is a valve that can do this mechanically no?

Improve this question
$\endgroup$
2
  • $\begingroup$ You need to keep it pressurised, and ideally cold. Having it just at atmospheric pressure is not enough to keep it from going flat. $\endgroup$ – Jonathan R Swift Jul 13 '20 at 10:01
  • $\begingroup$ Sucking the liquid out of a sealed bottle will cause the gas to come out of solution to fill the void and make it go flat extra quick. $\endgroup$ – Transistor Jul 13 '20 at 11:26
1
$\begingroup$

Add air or C02, using a pump,to keep the contents above atmospheric pressure or at the pressure of the soda bottle. Not sure what that is as I have never measured it, but some seem to be significant and they can push out quite a bit of the contents.

That means you will need two barbs to the lid. Consider making special lids - perhaps out of brass or stainless so that the pipe connections are more reliable.

This, of course, means that you only have to control delivery, just a simple delivery valve may do.

Also it will be a good idea to have oneway valves on the air (C02) supply to prevent backfeeding from any soda bottle into the one being used. A valve to allow changing the soda bottle would be a good addition.

Improve this answer
$\endgroup$
1
$\begingroup$

Without storing the soda in bags, I think you will struggle to find a solution that works better or even at a lower cost than the syrup & carbonated commercial solution. Mechanical check valves are not going to work well enough at the very low pressures we'll find here. and solenoids just complicate a system that I assume you are trying to keep simple to avoid the commercial solution.

Improve this answer
$\endgroup$
0
$\begingroup$

Spring-loaded Gravity-flap valves should work as monodirectional pressure stabilisers at an air intake. I don't know how this would affect shelf life of fluid being distributed but it's an idea at least

Improve this answer
$\endgroup$
1
  • $\begingroup$ I suggest you elaborate on your response. Currently the response is more like a comment. $\endgroup$ – Mahendra Gunawardena Jul 28 '20 at 4:01

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.