hx to db - what to expect?

hedonist222

I’ve been using an Appartamento for about three years now

My machine was set to 12 bar at the group head

My average flow is 7.5 ml/s

I read a lot about people saying rotary pumps push out more water? 12 ml/s.

I don’t understand this. Isn’t water flow a function or output of pressure?

Just wondering if I’ll need to grind coarser? I’m contrast to my Appartamento’s vibratory pump

DavecUK

hedonist222 The best way to think about this is not worrying about the maximum flow rate of the pump too much. This just affects how quickly the headspace fills above the portafilter and the soft/or not start on the coffee puck. The E61 actually has a preinfusion chamber, just to mellow the rapid output/pressure rise of the rotary pump once the headpace is filled.

If you extract an espresso with 40g over 30 seconds and if we assume that’s 38ml of liquid , because there will be some solids in there. That’s a flow rate of only 76ml per minute.

Whether the pump is capable of 1000ml per minute or 200 ml per minute, doesn’t really make any difference, because at the same pressure the coffee puck determines the flow. So Vibe pump vs rotary makes little difference…The main difference: vibe pumps are usually much noisier than a rotary (the exception being the Lelit quiet Vibe pumps, which are significantly quieter than the standard vibe pump, but not as quiet as a well implemented rotary pump)

Cuprajake

the pressure is create by the puck, so your grind setting will or should be the same, the added benefit of something like a bianca is you can pull the pressure back with the flow control,

bar that it will behave very much as your hx just a whole lot more stable

hedonist222

Cuprajake

But what about the 8ml/s vs 12ml/s

MediumRoastSteam

hedonist222 - that’s not pressure. That’s flow rate, I.e.: how much water the pump can deliver over a given time interval.

As said above, if there’s no restriction…. There’s no pressure.

With a higher flow rate, you’ll build up pressure quicker if there’s a restriction, I.e.: your coffee puck. If there’s no restriction, then there’s no pressure, just water flowing at that rate.

Cuprajake

Dont forget that most e61 has its own natural infusion so they still ramp up there not instant.

Cuprajake

If you can add flow control then you can control this

Wll did some good vids of flow control and water flows