Lelit Bianca flow control range

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Ursego

#1: Post by Ursego »

Hi Bianca owners, what are the factory settings for the flow rate (in gr/sec) when the FC paddle is "fully closed" and "fully open"?

It's easy to define flow rate: put a cup on a scale and pour water (without the portafilter) for 30 seconds. Then divide the resulting weight by 30.

For the sake of experimentation, I want to "logically" limit the range of my ECM FCD by setting the "minimum" in the 10 o'clock position, and the "maximum" in the 2 o'clock position, to mimic the Bianca. For that, I need to find the real physical "fully closed" position.

If you have changed the factory settings (by unscrewing and moving the paddle), what your new range is?

Smo

#2: Post by Smo »

The FC damper is "completely closed" - no flow at all.




In 30 seconds.
Red - paddle position.

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Jeff
Team HB

#3: Post by Jeff »

There is no "pressure" associated with the position of the lever and the "flow" is only at the number when there is no restriction.

The higher the flow through the machine (not the position of the lever), the more the pressure drop between "pump" and in the basket will be for a given valve position. The setting of the valve changes the relationship of the flow into the basket to the pressure drop across the valve.

Think about the two extremes. No matter the setting of the valve, if there is nothing creating back pressure (no basket) the pressure in group will be zero. No matter the setting of the valve, if you've got a blind basket, the pressure will very quickly be that of the limit set by the pump bypass or OPV.

dmau9600

#4: Post by dmau9600 »

Glad I found this thread, as I just installed the LUCCA flow control on my Quick Mi Vetrano 2B Evo. So, pretty similar machine to the Bianca.

Tha Lucca flow control is similar to the Bianca in that it has a limited range of motion, as the paddle touches the machine on open and closed. Although it's not as infinitely controllable as other flow control devices, I prefer the usability and predictability of this style.

When I installed the flow control so that all the way to the left was fully closed, I was only getting about 4g/s flow when fully opened. This seemed too slow and limiting for a rotary pump machine, so I have since adjusted it to get ~2.5g/s in closed position to ~7.5g/s in the fully opened position. Stock valve was pushing closer to 9g/s.

This seems like a pretty good usable range, but I'm curious if I should be skewing toward higher flow when fully opened, or lower flow when closed?

Here are the results of 20s runs at opened, half and closed.






Nunas
Supporter ♡

#5: Post by Nunas »

It's a trivial matter to remove the knob and install a radio or electric guitar knob in its place. You'd then be able to experiment with the full range of the control.

dmau9600

#6: Post by dmau9600 »

I suppose I'm just being picky, but I really prefer the usability of the Bianca-style devices with smaller ranges of movement.

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Ursego (original poster)

#7: Post by Ursego (original poster) »

dmau9600 wrote:When I installed the flow control so that all the way to the left was fully closed, I was only getting about 4g/s flow when fully opened. This seemed too slow and limiting for a rotary pump machine, so I have since adjusted it to get ~2.5g/s in closed position to ~7.5g/s in the fully opened position.
Thanks for your reply!

So, you have the flow rates range from 2.5 to 7.5 g/s. The full way of the paddle in your machine is something like 5/8 of a turn (same as Bianca).

Unfortunately, the same 5/8 cover a smaller range on my ECM Puristika. I have a feeling that this difference is because the Veterano and the Bianka have the rotary pump. It generates more powerful flow than the vibration pump of my Puristika, so you enjoy more flow on the same opening of the FCD. As the result, the Lucca/Bianca paddle travels less until it reaches the desired maximum. It would be interesting to hear from owners of rotary machines with ECM FCD.

Here is what I measured on my machine:

1/8 - 1.6
1/4 - 2.8
1/2 - 4.9
3/4 - 5.7
1 - 6.4
1 1/4 - 6.9
1 1/2 - 7.1
1 3/4 - 7.8

Let's say, I make 1/4 (2.8 ) my "minimum" (since 4.9, which is 1/2, is too much for pre-infusion). Then I move the paddle another 3/4 (that is slightly more than 5/8, but it's ok - I can make the range 10:30 to 1.30 rather than 10 to 2 o'clock). So, the "maximum" position is 6.4.

After some experimenting, I have increased the range and made it 1 full turn in order to have 6.9 as the "maximum". That flow rate is pretty close to 7.5, so there must be no practical difference, I believe.

All that game with more than one turn was driving me crazy! That is why I wanted mimic the Bianca. One full turn is still fine since it gives me a good visualization - I see where I am just looking at the knob.

dmau9600

#8: Post by dmau9600 » replying to Ursego »

I'm curious - have you tried increasing the pressure at your pump? I wonder if increasing the pressure at the pump would provide a higher flow rate across the range of the valve?

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Jake_G
Team HB

#9: Post by Jake_G » replying to dmau9600 »

It will work like that, yes.

However, I would err on the side of lower flow than higher flow.

Think of the flow control as an accelerator for you shot. You can push harder all you want with more flow, but you don't have any brakes to slow things down. All you can do is push less hard, and this makes controlling the pressure at the group more difficult than it needs to be if your minimum flow is too high. If your minimum flow rate is higher than a normal espresso pour, you'll have a tough time limiting the brew pressure.

Back to the accelerator analogy, if you are accelerating up a hill without brakes, it is easy to slow down, because gravity is on your side. This is the case when the puck wants to flow more than the flow control can supply. You let off the gas and the pressure falls.

Conversely, if you driving down a hill with no brakes, it can be quite impossible to slow down. This is the case when the minimum flow setting on the FCD is higher than the puck wants to flow. You close the valve off, but you're still supplying enough flow that the pressure won't drop.

I prefer to have my low end flow set to zero and deal with the limited upper end of the flow. My GS/3 tops out a 7ml/s with the pump set to 9 bar and is closer to 5ml/s at 6 bar. I don't have any issues with this "slow fill" pulling delicious shots. And having the ability to choke the flow is critical if you ever want to try preinfusion pressures of 2 or 3 bar.

Cheers!

- Jake
LMWDP #704

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Ursego (original poster)

#10: Post by Ursego (original poster) »

dmau9600 wrote:I'm curious - have you tried increasing the pressure at your pump? I wonder if increasing the pressure at the pump would provide a higher flow rate across the range of the valve?
Before I started measuring, I drew a table (I'm publishing a historical document!):



As you can see, I intended to measure at different pressures. But I was surprised to find that the flow rate was almost the same at all pressures! Seeing that, I did not fill in the whole table. At first I thought I would crank the pressure to 12 and be able to simulate the flow rate of a rotary pump, but I was wrong.