Originally Posted by BrewingRob
These caught my attention... But... What exactly do they do? What is the advantage? Are they just for foam reduction, or is there an effect on head and mouthfeel?
I'm pretty sure their purpose is... If you have a beer that you want carbed with, say, 18psi. You'll want to keep that pressure because if you decrease it, say to 10 psi for too long then the pressure in the keg/beer will eventually equalize.
But you also don't want to try to serve a 18 psi beer on a regular tap unless you have a crazy amount of beer line. So this faucet makes it so that when you open up the faucet you can increase the resistance (make the opening for beer to exit smaller) and thus control the pour so it doesn't just come out like a rocket and give you a cup of 1/4 beer 3/4 foam.
Corrections are welcome, I've never used one personally.
- ISM NRP