Woh, you've queezed 110lpm through a 22mm pipe? The fluid velocity must be incredible.
Here's 80lpm through a 22mm pipe on my processor
http://www.youtube.com/watch?v=1v1w6chKYosThis is fine for discharge pipework in relatively short runs but definitely not for suction - the problem is getting cavitation when the Methanol/biodiesel mix is approaching the point where the Methanol is starting to boil - even the slightest resistance can cause cavitation and this dramatically affects the pump's performance and ability to drive the venturi.
Every pump's performance is different, and for the same maximum flow rate two pumps can have different inlet sizes, presumably a decision by the manufacturers based on anticipated suction run length. There are some general rules on fluid velocity for pump inlets and outlets, they all vary depends on whose advice you follow, but they all allow roughly twice the outlet velocity than the inlet velocity. I'll have to see if I can find my notes but I'm pretty sure 80lpm through 22mm is way over all of the recommended inlet velocities
Generally if you go by the inlet size to determine the pipework sizing there's not much to get wrong.
