Watch this video. They state that both counters average 5 fuel/second and to expect 8-10 fuel per second to be counted by each boiler. Also, there is a capacity limit where any excess fuel will overflow and spill onto the floor.
https://youtu.be/bJQ4kMwOGtI?list=PL...dulQOTBCJv9 t
You can slightly see the mechanism that moves balls into the counter. From what I remember from a photo at the field unveil, it looked similar to a CNC mill umbrella tool change carousel. I'll try to get the exact photo later.
http://parts.haascnc.com/medias/SRD9...jk2ZDM1ZWQ2MzE