Why do these E61 labels call the 1st exhaust chamber the "preinfusion chamber"?
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I've been studying the E61 group head lately (Thank You all again for all of the wonderful information here!!) and I'm puzzled as to the naming of the 1st exhaust chamber as the "preinfusion chamber"? Here's one of many examples.
It seems to me that both the exhaust valves are closed at the start of the pull and both of their chambers are open to the exhaust port and therefore filled with air. Once the lever is rotated, the lower exhaust valve and then the upper exhaust valve close before any water is introduced into the chamber (called "Cam Pocket Area" in the linked image) that connects to the dispersion area and coffee puck. Continuing the lever rotation, the brew valve is opened and only at this point does water flow and optional preinfusion start ... remember what's labeled as the "preinfusion valve" is already closed and the "preinfusion chamber" is empty, so they have nothing at all to do with preinfusion. In fact they remain closed until the shot extraction is completed and they exhaust the pressure remaining in that brew circuit ("cam pocket area" to portafilter basket) once the brew valve closes off the water supply again.
This whole process can be seen in this video. So why is this called "Preinfusion Valve" and "Preinfusion Chamber"? It seems to me that they have nothing at all to do with preinfusion. Please enlighten me (and rescue my Friday night)!
It seems to me that both the exhaust valves are closed at the start of the pull and both of their chambers are open to the exhaust port and therefore filled with air. Once the lever is rotated, the lower exhaust valve and then the upper exhaust valve close before any water is introduced into the chamber (called "Cam Pocket Area" in the linked image) that connects to the dispersion area and coffee puck. Continuing the lever rotation, the brew valve is opened and only at this point does water flow and optional preinfusion start ... remember what's labeled as the "preinfusion valve" is already closed and the "preinfusion chamber" is empty, so they have nothing at all to do with preinfusion. In fact they remain closed until the shot extraction is completed and they exhaust the pressure remaining in that brew circuit ("cam pocket area" to portafilter basket) once the brew valve closes off the water supply again.
This whole process can be seen in this video. So why is this called "Preinfusion Valve" and "Preinfusion Chamber"? It seems to me that they have nothing at all to do with preinfusion. Please enlighten me (and rescue my Friday night)!
LMWDP #581 .......... May your roasts, grinds, and pulls be the best!
- Jake_G
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The preinfusion valve opens when the applied pressure from the pump exceeds the pressure from the spring beneath it, which is holding it closed with the lever in all but the exhaust positions. This pressure varies from 1.5 bar to 4 bar, depending on the specific machine.
When the preinfusion valve opens, water trickles into the preinfusion chamber. While this trickling is occurring, the supply pressure to the puck can't increase above the cracking pressure of the preinfusion valve. This gives you roughly 6 seconds of reduced pressure on the puck at the beginning of each shot.
Only one the preinfusion chamber is full does the pressure rise to full brew pressure.
The size of the chamber determines how long the preinfusion will last.; the rate of the spring holding the preinfusion valve closed determines the preinfusion pressure, and the orifice size in the gicluer determines the available flow into the group at the preinfusion pressure.
Hope this helps!
- Jake
When the preinfusion valve opens, water trickles into the preinfusion chamber. While this trickling is occurring, the supply pressure to the puck can't increase above the cracking pressure of the preinfusion valve. This gives you roughly 6 seconds of reduced pressure on the puck at the beginning of each shot.
Only one the preinfusion chamber is full does the pressure rise to full brew pressure.
The size of the chamber determines how long the preinfusion will last.; the rate of the spring holding the preinfusion valve closed determines the preinfusion pressure, and the orifice size in the gicluer determines the available flow into the group at the preinfusion pressure.
Hope this helps!
- Jake
LMWDP #704
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Okay, thank you, that makes good sense and I see that function in the pressure profile. REally appreciate that you've given more variables I can tweak later too. Cool! So the lower exhaust spring is a much higher force spring that requires the cam to open it versus typical brewing pressure (although it could also be set as a safety function I guess). It's interesting that I've found many videos on the E61 operation where "experts" explain those lower valves, but none have given this point-on view.
LMWDP #581 .......... May your roasts, grinds, and pulls be the best!
- Randy G.
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For more info on how the E-61 works, consult the Vibiemme Domobar Double owners manual, (PDF download) pages 5 through 8. (DISCLAIMER: I created the manual but the download is free, hosted on Stefano's website, Espressocare.com)
EspressoMyEspresso.com - 2000-2023 - a good run, its time is done
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Thanks yet Again Randy! THat's the best most thorough and easy to understand explanation I have seen. Bravo!
LMWDP #581 .......... May your roasts, grinds, and pulls be the best!
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Wow,just wow! THe E61 is really a thing of beauty, isn't it!
LMWDP #581 .......... May your roasts, grinds, and pulls be the best!
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Randy, THat's the best, most thorough and easy to understand explanation I have seen. Bravo!Randy G. wrote:For more info on how the E-61 works, consult the Vibiemme Domobar Double owners manual, (PDF download) pages 5 through 8. (DISCLAIMER: I created the manual but the download is free, hosted on Stefano's website, Espressocare.com)
LMWDP #581 .......... May your roasts, grinds, and pulls be the best!
- Randy G.
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As corny as it may sound, as a retired teacher I always am gratified when my efforts helps someone to learn. Ya, it's ego a bit, but that actually helps!Tonefish wrote:Randy, That's the best, most thorough and easy to understand explanation I have seen. Bravo!
Thanks for taking the time to say it helped.
EspressoMyEspresso.com - 2000-2023 - a good run, its time is done
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Not corny at all. Teaching is one of the most underappreciated professions. It is so vital to our human progress and individual development yet so woefully under-rewarded in our society. Appreciating what you do/did, and all of the people I am sure you have helped deserves far more than another big ... Thank You!Randy G. wrote:As corny as it may sound, as a retired teacher I always am gratified when my efforts helps someone to earn. Ya, it's ego a bit, but that actually helps!
Thanks for taking the time to say it helped.
LMWDP #581 .......... May your roasts, grinds, and pulls be the best!
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So, my understanding is that, when PI opens, air in PI chamber gets compressed (like remaining air in the headroom); that adds to the force of the spring, so pressure isn't kept at 1.5-4 bar for say 6 seconds, but is gradually rising towards pressure supplied by the pump. So effectively, PI chamber just slows down pressure ramp-up to something like 6 second. Checked some youtube videos and it looks like thatJake_G wrote:The preinfusion valve opens when the applied pressure from the pump exceeds the pressure from the spring beneath it, which is holding it closed with the lever in all but the exhaust positions. This pressure varies from 1.5 bar to 4 bar, depending on the specific machine.
When the preinfusion valve opens, water trickles into the preinfusion chamber. While this trickling is occurring, the supply pressure to the puck can't increase above the cracking pressure of the preinfusion valve. This gives you roughly 6 seconds of reduced pressure on the puck at the beginning of each shot.
Only one the preinfusion chamber is full does the pressure rise to full brew pressure.
The size of the chamber determines how long the preinfusion will last.; the rate of the spring holding the preinfusion valve closed determines the preinfusion pressure, and the orifice size in the gicluer determines the available flow into the group at the preinfusion pressure.
Hope this helps!
- Jake
Everybody / anybody agree with me ?