E61 pre-infusion chamber volume and pressure? - Page 2

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boren (original poster)

#11: Post by boren (original poster) »

Jake_G wrote:When the PI spring is overcome and the valve is cracked open, the pressure will remain at the cracking pressure of the PI valve until the chamber is filled.

Pressure will not rise until the chamber is filled, and then it will ramp up to the main brew pressure.
Interesting. So if there's a pause, and if after reaching 9 bar the pressure gradually reduces anyway (due to puck degradation), then this ultra-modern "best practice profile" is not that different from what happens in an E61 shot.