Curious what flow rates those with flow control devices are getting (if you something like a Bianca) or are using (if you have something with unlimited range). I just installed the LUCCA flow control on my Quick Mill Vetrano 2B Evo. 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?

@"dmau9600"#p23478 Can't remember the range on the Bianca, but it's more than sufficient. In an E61 group there are 3 springs. 1. Top group valve, pushed open by cam (leave this alone) 2. Preinfusion chamber valve (opens at 4 bar). The stiffer valve spring is to replace this, to it only opens at 11-12 bar 3. Vent valve, with spring that opens approx 12 bar The idea is not not have an operational preinfusion chamber as this interferes with profiling. you can replace the preinfusion spring with the stiffer one and remove the vent spring and valve (or leave it, although the group action might be a bit stiffer). Clives advice is not optimal on this regarding the preinfusion spring..

@"dmau9600"#p23484 Effectively yes.

Flow Control - Flow Rate Range?

DavecUK

dmau9600 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?

I guess it depends on what shots you’re trying to do. For Normal espresso shots, your ratio will be about 1:3 maximum 1:3, for a Lungo (or Turbo shot as the next generation are calling it), you might push to 1:5

4g/s will allow for 120ml over 30s….more than enough for these shot styles. However, being able to close the valve completely, will allow you to bloom the puck for a period of time, then continue the shot. Me personally, I would set it to be able to close off the valve completely.

dmau9600

DavecUK

Thanks for the quick response Dave! So, you wouldn’t be as concerned with the maximum flow rate being in the 4-5g/s range?

I do a mix of medium-light to darker roasts. Nothing super light generally.

Part of my goal would be to be able to pull a pretty “traditional” shot with darker roasts, starting at full open, then just decrease pressure slightly. Then, for the medium-light roasts, I like to start with slower pressure build, hit it hard, the ramp back down.

Do you know range the Bianca offers? Do you know if the stiffer valve springs alter the usable range? I kept the softer stock spring when I installed at the advice of Clive.

DavecUK

dmau9600 Can’t remember the range on the Bianca, but it’s more than sufficient. In an E61 group there are 3 springs.

Top group valve, pushed open by cam (leave this alone)
Preinfusion chamber valve (opens at 4 bar). The stiffer valve spring is to replace this, to it only opens at 11-12 bar
Vent valve, with spring that opens approx 12 bar

The idea is not not have an operational preinfusion chamber as this interferes with profiling. you can replace the preinfusion spring with the stiffer one and remove the vent spring and valve (or leave it, although the group action might be a bit stiffer). Clives advice is not optimal on this regarding the preinfusion spring..

dmau9600

DavecUK

I hate to be dense, but any easy way you can explain what switching to the stiffer spring would do? I’m not direct plumbed yet.

Also, should I be less concerned about the flow rate range and just ensure that my flow control config allows me to effectively control pressure at the group head (I understand the pressure control is indirect with flow control, but the end result is real)?

DavecUK

dmau9600 It effectively stops the preinfusion chamber filling at 4 bar…thus disturbing the profile. The spring doesn’t allow the valve to open until you vent the group.

dmau9600

DavecUK so you get more direct and immediate control of the pressure since you’re not accounting for that extra vessel?

DavecUK

dmau9600 Effectively yes.

tompoland

Still playing and learning with this so bear that in mind.

On the Strietman CT2 I’m using an Acaia Lunar 2021 because with some modifications (see https://coffeetime.freeflarum.com/d/956-acaia-lunacy-2021/2 ) to get a handles on flow rate. I’m aiming for 1ml/sec for a dark roast (sometimes medium) 1:1.5 - 1:2.0 ratio. It works well in that context.

I’m playing around (without success so far) with light roasts on the Decent and flow rate for that is much higher. I’ll make a note of exactly what it gets up to and update here.

DavecUK

dmau9600 it’s also worth checking the condition of the o’rings and that little pieces are not blocking the jet.

https://coffeetime.freeflarum.com/blog/745-lelit-flow-control-valve-and-coffee-sensor-version

Amberale

Some folks seem to get all concerned that their new, high-fallutin’, shiny spaceship of an espresso machine has had its unburdoned flow rate reduced by the addition of a FCD.
Sort of like a guitar amp that goes to 11, “I used to have 30 grams a second!”.

For most shots I am using about 60g of water in 30-40 seconds(about a third stays in the puck).
So about 2 g/sec average.

Unless one is making tea, sorry using barely warmed up green beans to make some sort of Tissane, I can’t see how you would ever need more than around 4-5g/sec.

dmau9600

Amberale

Thank you! Although a little sassy, I appreciate the insights and feedback. I’ve adjusted the FC to bias towards being fully closed in the closed position, and getting around 5g/s in the open position.

With a blank PF, it takes around 10s to reach peak pressure at the group head, but I have much better control of the pressure at the low end now.

Amberale

dmau9600
That sounds fine.
Once you put about 18g of ground coffee in your basket it should reduce the volume of water required to bring that group head pressure up to your pre-infusion rate (I use 2bar) such that it should take about 5 seconds.

coffeealex

Flow rates always confuse me. On my Bianca with needle fully closed (when paddle to the left), the flow rate is approx 117 grammes over 20 seconds when paddle fully open to the right, which I thought was ok according to Lelit. Is that ok for a flow rate? or does it not really matter as long as the extraction is good?

Doram

coffeealex the flow rate is approx 117 grammes over 20 seconds when paddle fully open to the right, which I thought was ok according to Lelit. Is that ok for a flow rate? or does it not really matter as long as the extraction is good?

117g over 20 seconds is 5.85ml per second, which I think is reasonable for unrestricted flow + as you say, if the coffee is good then you’re all set.