I’m trying to build fully automated beer tap which can give precise amount of beer (with approximately same foam/beer ratio for every single transaction) by RFID/NFC user authentication. I would like to deactive manuel tapping and want to control pouring by only pneumatical or solenoid valves.
Ahhh the quest for the perfect consistent pour… The problem is that were are a lot of variables. A warm glass can cause nucleation when poured into resulting in larger foam. Also the first run through your faucet and shank can cause extra foam because they are warmer than the serving temp and that will increase foam. Different ingredients in beet will change the amount of foam. For example wheat beer has more proteins in it and as a result more foam. I supposes most of these can be over come it you have a stable temp, and always serve the same beer, but what’s the fun in that.
When I started the project long ago, I remember speaking to a manufacturer of the valve we all used. Their words were, in effect, “We tested a lot with beer, the direct-acting design just isn’t good for it.”
That said, I do know better parts exist, I just don’t have a source/supplier for them. One option you could consider is to find a “pinch valve” – this works by kinking some tubing rather than directing the flow through a valve chamber.
I believe @scottresnik has had better luck with stainless steel ball valves; you might be able to find a supplier on alibaba. Since these valves work more like stepper motors, they might also be a superior choice for volume limiting (ie you can open the valve to a precise percentage rather than all or nothing).
Hope that helps. Please keep us posted on your quest; we’re always glad to hear about alternative/improved designs…
Thank you all. I’ve already had similar one what @scottresnik sent, but it is pnuematic. Like this: http://goo.gl/QT27dA. I’ll try it on and share the results.
Also I’m looking for something like these: http://en.celli.com/products/beertaps-and-valves_3/postmix-valves_18/ . I’m pretty convinced that I can’t realize what is in my mind without any specialized component for pouring. I’ve ordered and try it too. Have you ever encountered any proper automated shranks like Celli’s?