Hi all,

After lots of reading about lower brewing pressure when pulling shots, I've decided to test it on my own.

I have a Rocket Evo V2 with a rotary pump that was running at 9 Bar of pressure at the gauge.

Decided to lower it to 6 Bar of pressure at the gauge. I've adjusted it with the blind basket and the reading on the gauge.

Pulled a shot with the exact same adjustments on the grinder and dose.

I was pretty surprised that the shot pulled at the same rate that when I was pulling at 9 Bar ?!?! Around 27-30 seconds for the same yield.

Am I missing something here ? I was expecting the shot to take more time to pull the same amount since there is a 40 psi difference.

Thanks

Jo

Any thoughts ?

See here for an explanation:

Playing with Pump Pressure: Part Uno

Might have missed something but that doesn't really explain why this would be happening ?

Also did some test and in 30 seconds, I'm getting around 325ml.

30 seconds just flow no PF in place yields 325 ml - is that what you mean?

Yes sorry, missing some details

Did the test with 9 Bar of pressure and I'm getting 405-410ml in 30 seconds.

Might have missed something but that doesn't really explain why this would be happening ?

My guess is that higher pressure compacts the grinds more and this reduces flow - roughly canceling the normal effect of higher pressure.