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pressure profiling with vibe pump
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frank828
Senior Member


Joined: 23 Feb 2011
Posts: 580
Location: Los Angeles
Expertise: Professional

Espresso: GS3
Grinder: RoburE, Kenia
Vac Pot: Hario
Drip: Brazen, CCD, Aeropress, V60,...
Roaster: Behmor, Air Crazy
Posted Thu May 17, 2012, 1:32pm
Subject: Re: pressure profiling with vibe pump
 

here's my solution to adding pressure profiling onto a vibe pump system.  

"Pressure Profiling via 3-way directional solenoid valve"
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D4F
Senior Member


Joined: 15 Mar 2012
Posts: 1,897
Location: USA
Expertise: I like coffee

Espresso: Gaggia Classic PID
Grinder: Preciso
Posted Thu May 17, 2012, 7:04pm
Subject: Re: pressure profiling with vibe pump
 

More here

http://coffeegeek.com/forums/espresso/machinemods/567450

Click Here (www.home-barista.com)

 
D4F also at
http://www.gaggiausersgroup.com/
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GlennV
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Joined: 27 Oct 2011
Posts: 29
Location: UK
Expertise: I love coffee

Posted Fri May 18, 2012, 2:55am
Subject: Re: pressure profiling with vibe pump
 

frank828 Said:

here's my solution to adding pressure profiling onto a vibe pump system.  

"Pressure Profiling via 3-way directional solenoid valve"

Posted May 17, 2012 link

It doesn't have to be that complicated - just tee into the line between pump and boiler (before or after the existing OPV) and go via a 2-way (ie boiler fill) solenoid and secondary OPV (or needle valve) to the drip tray/pump input. That's if you're primarily interested in pressure. If you want to do what Andy's talking about, which is primarily controlling flow, then you're probably better off with a needle valve in line with the flow (and a 2-way to bypass it).
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frank828
Senior Member


Joined: 23 Feb 2011
Posts: 580
Location: Los Angeles
Expertise: Professional

Espresso: GS3
Grinder: RoburE, Kenia
Vac Pot: Hario
Drip: Brazen, CCD, Aeropress, V60,...
Roaster: Behmor, Air Crazy
Posted Fri May 18, 2012, 4:09am
Subject: Re: pressure profiling with vibe pump
 

GlennV Said:

It doesn't have to be that complicated - just tee into the line between pump and boiler (before or after the existing OPV) and go via a 2-way (ie boiler fill) solenoid and secondary OPV (or needle valve) to the drip tray/pump input. That's if you're primarily interested in pressure. If you want to do what Andy's talking about, which is primarily controlling flow, then you're probably better off with a needle valve in line with the flow (and a 2-way to bypass it).

Posted May 18, 2012 link

hmm that sounds like it might work but what would happen to the total pressure when the 2 way valve is opened up and both streams of water(one 9bar  and one adjusted to get you 5bar) are combined and go into the boiler?

is the 2nd OPV valve attached to the hose without the 2-way solenoid so that when the 2nd line is blocked off, the water will only travel through the 2nd OPV and then give you 5bar?  what happens then when you to go full 9bar?  open up the 2-way solenoid?  i would think this would drive up the total pressure to the boiler quite a bit initially.   I'm thinking maybe add a check valve on the end of the 2nd OPV side...but how effective would that be when there is still 5bar trying to open up the check valve with 9 bar on the other side pushing against it.   Without a check valve, you'll have water going in reverse up to the 2nd OPV valve.  Do these run in reverse or just evacuate all the water being sent in reverse?  Would you possibly have to raise the first opv higher than 9bar to balance out the pressure being used to go back up the tubing on the other end and either evacuating or being pushed back up the OPV?  

or is the 2-way attached to the OPV side and then full pressure on the other hose?  if this were the case then when the solenoid is activated to send water to the 2nd OPV, you'll again have to deal with the combination of water pressure from both hoses.    I would expect the total pressure to be affected because the first OPV after the pump is set at a certain resistance and there may be an initial pressure drop off because both lines will have pressure applied.

maybe im overthinking this but the 2way valve solution seems to give me more questions.  initially it seemed plausible, though.


my method, adjust the first OPV to get full 9bar at the brewhead with only one water line feeding the boiler.  When i want to go 5bar, i activate the 3 way which then cuts off the water to the full pressure line and switches the pressure over to the 2nd OPV and then straight to the boiler(shuttle valve closes off the side with less pressure) without any other water from the other line to interupt the total pressure.  


both may work, but in my head, i feel like the 3-way directional control solenoid with 2nd opv and shuttle valve may be more consistent and reliable.
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frank828
Senior Member


Joined: 23 Feb 2011
Posts: 580
Location: Los Angeles
Expertise: Professional

Espresso: GS3
Grinder: RoburE, Kenia
Vac Pot: Hario
Drip: Brazen, CCD, Aeropress, V60,...
Roaster: Behmor, Air Crazy
Posted Fri May 18, 2012, 4:27am
Subject: Re: pressure profiling with vibe pump
 

i dont know if im completely off in my questioning...it's almost 4:30am and my brain is trying to process things...bleh

im going to bed

someone straighten me out
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AndyPanda
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AndyPanda
Joined: 12 Jul 2010
Posts: 769
Location: San Francisco Bay Area
Expertise: I love coffee

Espresso: Olympia Cremina, Various...
Grinder: Mazzer Major, Fiorenzato,...
Vac Pot: vintage Corey
Drip: AeroPress
Roaster: BreadMachine/HeatGun
Posted Fri May 18, 2012, 7:02am
Subject: Re: pressure profiling with vibe pump
 

tracerbullet Said:

Do you find a pretty good range of adjustability or does the dimmer / pump seem to be pretty touchy and that you only have a small range to work in?

Posted May 17, 2012 link

With my setup it is very smooth and I use the entire range.  I am testing this on a Gaggia Classic with an Invensys pump - I have the 3-way solenoid valve so there is no resistance other than the coffee puck (non-3way machines have that group valve that adds a resistance to the flow).
If I use the very lowest setting of the dimmer, I will get very, very slow trickle of water from the group and if I were to put a PF gauge on there it would take a long time to build up any pressure at all but it would eventually reach maybe 1 bar tops.   With the dimmer about halfway, I get about 5-6 bars and a decent flow.  Dimmer on full and it's standard, noisy pump, lots of flow and 9 bars with OPV bleeding off quite a bit.
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AndyPanda
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AndyPanda
Joined: 12 Jul 2010
Posts: 769
Location: San Francisco Bay Area
Expertise: I love coffee

Espresso: Olympia Cremina, Various...
Grinder: Mazzer Major, Fiorenzato,...
Vac Pot: vintage Corey
Drip: AeroPress
Roaster: BreadMachine/HeatGun
Posted Fri May 18, 2012, 7:31am
Subject: Re: pressure profiling with vibe pump
 

Regarding the other ideas (second valve, or using resistors).  I have been using resistors for a couple years on some of my vibe pump machines.  That is simple and effective and gave me a choice of 2-3 different pressure/flow settings from the pump.  The first one I did with a three position toggle switch and a couple of resistors in series with the pump.  The three position toggle let me bypass one or both resistors (by simply shorting across one or both of the resistors so there was no resistance - they are wired in series so shorting them puts the pump back to being directly connected without any resistance)

All I was trying to accomplish with that was to get a slow pre-infuse and it worked pretty well.  

What I was trying to accomplish with the dimmer was something else.  I wanted to be able to continuously adjust the flow/pressure while the shot was pouring.  This wasn't my idea - and it seemed contrary to what I had been reading/learning about espresso - but the more I play with it, the more sense it makes to me.  I'm starting to question the whole notion that 9 bars pressure=espresso and lower pressure = strong coffee.   Maybe 9 bars is actually just the pressure that happens to get you in the ballpark to be able to  have close to the right grind that brings out the best flavor for most coffees and the right depth to the coffee puck to have the water moving through the puck at about the right rate to get pretty good extraction with most coffees.  What if the pressure itself isn't really so important? -  I mean does the coffee extract differently because of being under pressure? or because of how the pressure is moving the hot water through the coffee puck?   (I don't know the answer - but the results I'm getting by focusing on flow rather than pressure really has me wondering)
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AndyPanda
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AndyPanda
Joined: 12 Jul 2010
Posts: 769
Location: San Francisco Bay Area
Expertise: I love coffee

Espresso: Olympia Cremina, Various...
Grinder: Mazzer Major, Fiorenzato,...
Vac Pot: vintage Corey
Drip: AeroPress
Roaster: BreadMachine/HeatGun
Posted Fri May 18, 2012, 7:48am
Subject: Re: pressure profiling with vibe pump
 

tracerbullet Said:

I guess what I'm really wondering, since I'd love to try this myself, is - does it work beautifully or if you did it again would you do it differently?

Posted May 17, 2012 link

If I were doing it again, I would do it exactly the same way.  It works beautifully.

I had read many, many posts (like the one at HB linked up a few posts) over the years where people say that a dimmer won't work because "the pump becomes confused" .... so I was fully expecting to have to modify the dimmer to limit how far it would reduce the power so I could keep the pump in a useful range.  But I found it worked perfectly without doing any modification at all.

I don't know if that is due to the specific pump in my machine (it's an older Classic from about 2000 or so) or if this particular dimmer works differently from the ones other people tried.  I just picked the one I picked because it was the cheapest one and because I wanted rotary instead of slider and I wanted one that wasn't a "push to click" type.  

I have one machine with a regular Ulka - I'll have to test it.  I have another machine with a really old Ulka (I have resistors on that one for a couple years now and it's working beautifully)  Not sure when I'll get time to try them but I'll report back if they behave differently.
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Frost
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Frost
Joined: 26 Jul 2007
Posts: 2,053
Location: Sierra
Expertise: I love coffee

Espresso: Isomac Venus
Grinder: Lelit PL53
Roaster: Poppery I w/variac, MET, BT
Posted Fri May 18, 2012, 8:00am
Subject: Re: pressure profiling with vibe pump
 

I have worked the series resistance method with both Invensys and Ulka pumps and find they both behave essentially identical. This method is so simple and effective I can't imagine why anyone would want to work with multiple bypass valves and OP valves. ......do it the modern way; with electricity.
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frank828
Senior Member


Joined: 23 Feb 2011
Posts: 580
Location: Los Angeles
Expertise: Professional

Espresso: GS3
Grinder: RoburE, Kenia
Vac Pot: Hario
Drip: Brazen, CCD, Aeropress, V60,...
Roaster: Behmor, Air Crazy
Posted Fri May 18, 2012, 9:28am
Subject: Re: pressure profiling with vibe pump
 

Well I picked up a dimmer switch so I'll hook it up before I do the other mod with the valves and 2nd opv.  

Bleh I hope my way wasnt all a waste of time/money.
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