'Pressure Profiling' With The Fluid-O-Tech TMFR Pump - Or, Wholesale Copying Greg Scace's Ideas - Page 23

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Maciolus
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Joined: 13 years ago

#221: Post by Maciolus »

@Carneiro and Eric: Do you have any updates on your projects with MGFR pump and motor?

I am willing to buy one and control it with Arduino - the brain of my heavily modified Rancilio S26.

The other option is to buy R/C brushless low kv outrunner motor with speed controller and attach it to a normal pump. Have you considered such an idea?

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Carneiro
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Joined: 15 years ago

#222: Post by Carneiro »

I've just received the pump. I have to buy connections, 24V power supply, 5V power supply and potentiometer to control it manually and test it. Later, an Arduino should take place.

I've never thought about other motor and rotary pumps. I was thinking about PWM the cheap vibe pumps, but the gear pump can bring the noise down and for sure is more robust, altough expensive.

Márcio.

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erics
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#223: Post by erics »

If you look at the literature available on the web and the several threads on HB re this subject, you should realize that this is a "whole new world". If you look at the Fluid-O-Tech website, http://www.fluidotech.it/Contents/Docum ... 1%20Ed.pdf ,you may come to the conclusion that this pump is destined to find its way into some advanced home espresso machines.

I reached that conclusion and initially wanted to buy that pump. After having some conversations with FOT-USA I changed that to the MGFR model - http://www.fluidotech.it/Contents/Docum ... 20unit.pdf . The only difference between the pump(s) I have on order and the one Marcio has received is that mine is equipped with a built-in relief valve and his is not - no big deal.

It's pretty easy to see that my original "pump idea", the FG100 is a drop in replacement for all existing vibe pump installations - well - with the exception of that 24 VDC power supply which takes up some space. Same applies to the MGFR except it is another inch or so in length - the exact dimensions are obviously in the pdf's. But, there is a big $ difference - about $500 when all is said and done. So, for now, this is simply a personal adventure. In the not so distant future, I would hope that the price of these pumps comes way down such that a drop-in replacement is more $ friendly.
Skål,

Eric S.
http://users.rcn.com/erics/
E-mail: erics at rcn dot com

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shadowfax (original poster)
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#224: Post by shadowfax (original poster) »

Maciolus wrote:The other option is to buy R/C brushless low kv outrunner motor with speed controller and attach it to a normal pump. Have you considered such an idea?
Sounds like the same end result as the TMFR pump, and the same required modifications to the bypass that I described in the beginning of this thread-only difference being that it will be your brushless motor rather than the 3-phase AC motor with phase drive/controller that the TMFR pump includes. Sounds like a tremendous amount of effort and probable expense when you can just get a TMFR for ~$300 and build a basic interface and controller for $1-200 more.

It'd probably be noisier, too, as the TMFR has the advantage of being a magnetically coupled, fully sealed pump.
Nicholas Lundgaard

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Carneiro
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#225: Post by Carneiro »

The MGFR manual says:
It is not advisable to install solenoid valves in the circuit; however, if necessary, the solenoid valve should only be installed after the pump. Solenoid valves installed before the pump should be avoided at all times. The internal diameter of the solenoid valve should be appropriately sized for the pump capacity. In order to avoid pressure spikes the solenoid valve should only be operated after the pump has stopped, allowing a few seconds to go by after the motor has been switched off. If the pump is equipped with a relief valve (bypass), it will act, in case of accidental overpressure, to limit the pressure, by means or
recirculating the fluid internally.
Yesterday I drilled M5x0.8 threads over the M4 threads of the Elektra Semiauto group. So now I can use a M5x1/8BSP adapter and a pressure gauge. The Elektra has no check valve or overpressure valve. Still using the vibe pump, I could see that, even if the pressure of the shot at the end is something around 10 bar, when I turn it off the pressure between the pump and solenoid rises to 16 bar (I think even more, but 16 bar is the maximum of the gauge). It takes some time to the pressure decline, unless you hit the coffee button again.

The vibe pump has kind of a check valve at the outlet (a rubber mushroom), so I guess this pressure spike is between the solenoid and pump outlet, only forcing the mushroom back to the metal. Curious that the original pump of this machine had a deformed mushroom, maybe if that could be the cause (or it was just an old and very used pump)?

I wonder if I will have this spike between the MGFR pump and the solenoid. Or if using a check valve after the pump would let the pressure rise between the check valve and solenoid but let the pump OK.

Márcio.

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mhoy
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#226: Post by mhoy »

Any updates?

Mark

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Carneiro
Posts: 1153
Joined: 15 years ago

#227: Post by Carneiro »

Does anybody can sell me time? :mrgreen: I was working to restore other machine and still missing connections for the MGFR... :oops:

Márcio.

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indend007
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#228: Post by indend007 »

If it possible, I give my whole life to you :)

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Carneiro
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#229: Post by Carneiro »

No need for such a sacrifice! :mrgreen:

Some update, I've tested the pump with a 24V source, a 5V source and potentiometer to control the speed with free flow and with a needle valve and pressure gauge. Very promising.

When the flow is free, very low noise, around 2 ml/s when the input is 0.3V and almost 30 ml/s when the input is 5V:
With the needle valve and gauge, some play with two different flows:
Hard to need more than 2500 RPM. It'll happen probably on the start of very tight ristretto shots if the controller wants to reach 12 bar, for instance.

Márcio.

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Carneiro
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#230: Post by Carneiro »

More news, I've tested the pump on Elektra Semiauto! A temporary assembly, but a check valve, teflon tube and connector to the SS hose of the HX, vibe pump power off, and ready to test!

I have to turn the solenoid on and then run the pump. More important is to never turn the solenoid off while the pump is running, or the pressure goes over the top - I have to put a expansion valve to avoid that. Probably the unit with the internal bypass valve will not have this problem, unless someone keep the pump running only with the bypass flow. To this manual setup, the potentiometer has a click to turn something on and it could be used for the solenoid, I just have to buy a small relay to do that.

More important are the shots. Well, did two so far, simulating a lever pressure profile and it was great. The Elektra is great but a little bit finick, almost every time ends like a gusher, and this two shots were more controlled. And the noise... Well, the same as above... I'll make videos later.

Márcio.