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:
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?