Re: VBM - quality not quite there
It’s the engineering skeptic in me that questions that wisdom
The main problem that I have is the spring itself or to put it in another way, the springs resistance value
The spring can control the speed of release depending on its tensile strength from fast to slow however that said it is a soft release
If one sets the OPV at 9 bar you are telling the OPV to release at that value
Looking at it another way? It will release pressure at the most crucial time. The optimum brew setting?
So the users changes the grind size and tamp strength to compensate and ensure the OPV valve does not trip and release as set pressure is reached continuously
The question remains what is the actual pressure after user compensation?
It surmise that it is under 9 bar more likely 7 or 8 bar
Ideally you don’t want the OPV to trip at all
If it is set just above at the ideal bar level the actual brew pressure will be aprox 1 to 2 bars below.
KK
It’s the engineering skeptic in me that questions that wisdom
The main problem that I have is the spring itself or to put it in another way, the springs resistance value
The spring can control the speed of release depending on its tensile strength from fast to slow however that said it is a soft release
If one sets the OPV at 9 bar you are telling the OPV to release at that value
Looking at it another way? It will release pressure at the most crucial time. The optimum brew setting?
So the users changes the grind size and tamp strength to compensate and ensure the OPV valve does not trip and release as set pressure is reached continuously
The question remains what is the actual pressure after user compensation?
It surmise that it is under 9 bar more likely 7 or 8 bar
Ideally you don’t want the OPV to trip at all
If it is set just above at the ideal bar level the actual brew pressure will be aprox 1 to 2 bars below.
KK

, but the pump pressure remains constant at about 4-5 bars, and the OPV responds to the resistance created BY the puck. so if an OPV is set at 12 bars, essentially it is being told to keep the resistance pressure from the coffee puck at 12 bars.
In the case of a plumbed in model inlet pressure from the mains + pump pressure is the total pressure supplied to the system so the pump may only be adding 5 or 6 bar depending on setup.
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