Fluid-o-Tech FG213 Gear Pump with Mean Well SDR-120-24 for Preinfusion Control?
Hey folks,
I’ve been diving into this awesome project and wondering if a Fluid-o-Tech FG213 gear pump paired with a Mean Well SDR-120-24 (24V, 5A, 120W) fits well. Can it be controlled from the board for preinfusion and other settings? Also, I’m curious about swapping the standard lever switch for a linear potentiometer: BI Model 404 https://eu.mouser.com/ProductDetail/BI-Technologies-TT-Electronics/404R10KL1.0?qs=LUfMuE0iDorszXH677fGaw%3D%3D to manually adjust pressure from the gear pump by lifting the lever, similar to Tate Mazer’s technique in this video (https://youtu.be/JlgXGrb4lVE?si=x4sSAlxf-_qxXNhM&t=651). Has anyone tried this or something close? Thoughts on compatibility and manual pressure control? Thanks!


I can think of three approaches to controlling flow with a rotary pump machine. The first is to control the flow of electricity to the motor which drives the pump. I don’t know if this is possible or not. I read the data sheet from Fluid-o-tech and it is not clear to me. We could ask them.
The second is to use a needle valve or other means of flow restriction. This is what the mechanical flow control devices do. I can think of two ways. In the first approach, we use a 3-way solenoid to create two paths of brew water. The first path is at full pressure, and the second path meets with flow restriction. So now we can have preinfusion, restricted flow, and full flow. The restricted flow path could flow through a manually adjustable needle valve, so you can tweak the restriction. Now the electronics can pull shots with preinfusion, then full pressure, then lower pressure. Or whatever.
Then the other approach is to implement an electronically controllable flow restrictor, but I’m not sure what device can be used.
Of these approaches, I like the 3-way solenoid approach the best. It requires some reworking of the machine, but it shouldn’t be too extensive.