Another preinfusion method for vibratory pump machines - Page 2
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vicroamer
- Posts: 128
- Joined: 16 years ago
I second mhoy's comment, well done.
I also run PI in my Silvia only I use a second OPV running off a bypass solenoid, it works a treat.
I also run PI in my Silvia only I use a second OPV running off a bypass solenoid, it works a treat.
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tombrazier
- Posts: 1
- Joined: 13 years ago
Just found this conversation when googling to see whether anyone else was doing the same as what I'm playing with.
I have a Gaggia Baby Class on which I'm controlling power to the pump by energising the coil for only part of each mains half-cycle. So a slightly different approach. I suspect your response curve is much more linear than mine, but mine has a greater resolution and, I imagine, a smoother flow.
Anyway, I thought I'd report that combined with a flow meter I'm now experimenting with PID controlling the flow of the entire extraction. Which means I get the same rate of flow regardless of grind and tamp, and also means I don't need an adjustable OPV. (The Baby Class's OPV is hard-wired to 11Bar as far as I can tell).
Results are variable so far - it's beginning to look like I need a different brew temperature now that I've reduced the flow rate. But I did get a very fine shot this morning, so I'm hopeful.
I have a Gaggia Baby Class on which I'm controlling power to the pump by energising the coil for only part of each mains half-cycle. So a slightly different approach. I suspect your response curve is much more linear than mine, but mine has a greater resolution and, I imagine, a smoother flow.
Anyway, I thought I'd report that combined with a flow meter I'm now experimenting with PID controlling the flow of the entire extraction. Which means I get the same rate of flow regardless of grind and tamp, and also means I don't need an adjustable OPV. (The Baby Class's OPV is hard-wired to 11Bar as far as I can tell).
Results are variable so far - it's beginning to look like I need a different brew temperature now that I've reduced the flow rate. But I did get a very fine shot this morning, so I'm hopeful.
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another_jim
- Team HB
- Posts: 13963
- Joined: 19 years ago
People have experimented with dimmers and SCrs. They found you can throttle the pump down to about 4 bar. Below that, there's no flow. I haven't heard of anyone doing it long term; so I'm not sure there's any info on how it affects pump life.
An alternative is to upgrading the valve on the steamer to a needle valve, and then to bleed water through it while making espesso. This works like a fully and rapidly adjustable OPV. Not as neat or easily automated as motor speed controls, but perhaps having a wider adjustment range.
Both approaches require an inline pressure meter, since the responses are quite non-linear.
An alternative is to upgrading the valve on the steamer to a needle valve, and then to bleed water through it while making espesso. This works like a fully and rapidly adjustable OPV. Not as neat or easily automated as motor speed controls, but perhaps having a wider adjustment range.
Both approaches require an inline pressure meter, since the responses are quite non-linear.
Jim Schulman
