frankmoss wrote:That's at 10 bar. Your 750mL/min is unrestricted (ie at 0 bar), right? So it's not comparable.

Hi I've been trying familiarize with all details (still learning). In short I think I'm having a similar issue with my ECM Giotto where I'm getting an excessive water flow rate. And if I understand Frank I cannot (or should not) measure my flow rate without resistance(0bar)?

Can I measure my water flow rate with a blind pf and calculate the amount at the return?

And if I understand Frank I cannot (or should not) measure my flow rate without resistance(0bar)?

The point Frank was making is that the unrestricted flow rate can not be compared to the pressurized flow rate quoted in the pump manufacturers material. I believe the unrestricted flow rate should be somewhere around 500ml/min.

jarviscochrane wrote:The point Frank was making is that the unrestricted flow rate can not be compared to the pressurized flow rate quoted in the pump manufacturers material. I believe the unrestricted flow rate should be somewhere around 500ml/min.

Thanks for explaining that. Basically, flow rate is dependent on pressure in a vibe pump, as erics's graph showed. According to that graph, completely unrestricted (ie 0bar) flow rate should be about 750 mL/min for your pump. Therefore, erics suggested that you might be missing a gicleur somewhere. Either way, that flow rate is not ridiculous and shouldn't cause the problem you described. The stuck one-way valve was likely the culprit.

Hey jarvis,

Thanks for the info...Just tried it and I got 500ml/min "Dead On!", I also tried measuring the flow from the return with a blind pf (9bar) and I got 200ml/min after the pre-infusion cycle...Now I have to figure out why I cant get perfect crema...It will require some further inquiry but since I have a vibe pump I suspect that I should increase my blind pf gauge to around 11bar so I can get ~9bar on a shot at the pf.

btw Canadiens are currently playing the Leafs and it's still scoreless.

In the end, the only flow rate that matters is the flow rate you have while pulling a shot, provided you do not have a dying pump and have super low volume. You can run a machine without any flow restriction, as long as your distribution, dose, tamp is correct you will get the correct extraction flow rate. The flow restrictor makes it easier to pull a shot especially on rotary pump machines. I have played with changing the restictor before to lower the rate of infusion but in the end, as long as your coffee cake is 100%, your flow rate during a shot will be just fine. If you are flushing water through the machine with the portafilter off, then yes, higher flow rates will have a faster drop in temperature. Restrictor or not you are still only pulling approximately 2oz in 28 seconds.