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I think I got to get out more often... I feel like Im slowly morphing into a geek of sorts. I just cant stop tinkering with stuff, or thinking of tinkering with stuff... The latest thought project revolves around trying to achieve the ideal brew pressure of 9 bars and OPV mods come to mind.
Ive been doing some thinking though, now, the law of thermodynamics would indicate that liquid under pressure will travel in the path of least resistance, which is what the OPV would provide so that the maximum pressure a vib pump can pump out is capped at 9 bars. However, the path of the water we are trying to push through would be the coffee in the basket tamped. So essentially, the puck is what provides the resistance (and therefore pressure). With an OPV set at 9 bars, if the coffee is ground too fine and packed so that it requires more than 9 bars to get water through it, nothing would come out at the head and the water would escape through the OPV instead back into the tank, something we call "choking". Similarly, if the puck was too coarse, or underdosed, it would produce coffee but a gauge would show that the brew pressure would not have gotten up to 9 bars.
I suppose what Im getting at is, if the grind is set properly and tamped consistently, the 9 bars of pressure would be "provided" by the puck rather than the OPV... So even if an OPV was at a higher setting of 12 bars, you would still get 9 bar brew pressure at the extraction.
I suppose the value of the OPV set to 9 bars is that it helps you determine where the limit is (dosing, tamping pressure) before it chokes but I wouldnt see how if the dose and tamp is kept the same, the espresso made from OPV of 9 bars would taste different to the OPV of 12 bars seeing as it would have provided the same resistance.
Is that logical?
Ive been doing some thinking though, now, the law of thermodynamics would indicate that liquid under pressure will travel in the path of least resistance, which is what the OPV would provide so that the maximum pressure a vib pump can pump out is capped at 9 bars. However, the path of the water we are trying to push through would be the coffee in the basket tamped. So essentially, the puck is what provides the resistance (and therefore pressure). With an OPV set at 9 bars, if the coffee is ground too fine and packed so that it requires more than 9 bars to get water through it, nothing would come out at the head and the water would escape through the OPV instead back into the tank, something we call "choking". Similarly, if the puck was too coarse, or underdosed, it would produce coffee but a gauge would show that the brew pressure would not have gotten up to 9 bars.
I suppose what Im getting at is, if the grind is set properly and tamped consistently, the 9 bars of pressure would be "provided" by the puck rather than the OPV... So even if an OPV was at a higher setting of 12 bars, you would still get 9 bar brew pressure at the extraction.
I suppose the value of the OPV set to 9 bars is that it helps you determine where the limit is (dosing, tamping pressure) before it chokes but I wouldnt see how if the dose and tamp is kept the same, the espresso made from OPV of 9 bars would taste different to the OPV of 12 bars seeing as it would have provided the same resistance.
Is that logical?
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