I just stumbled on this today because I am interested in flow metering - but for much smaller flow rates. I haven't been able to find any suitable flow meters for what I want.
Your YouTube demo looks very different from what you described in Post #55 as the customer now seems to be given a regular swipe card?
Have you any experience yet of how accurate the flow meters are? One thing that would concern me is if the customer could persuade the beer to trickle from the tap it might not register on the meter (if the flow rate was below 1 litre / minute)?
The company here advertised an ultra-low flow meter:
**broken link removed**
The output is just an LCD display. ... Maybe you could tap into the pulse output of the flow sensor. It seems to be a very sensitive device, with correction for viscosity, and basic 2% accuracy.