Guys,
It's time to wrap this thread up. It was initially going to be about a little 'project' to replace the vibration pump with a rotary pump, but then morphed into the installation of a variable speed gear pump, (along with all the associated flow control, pressure profiling, pre-infusion baggage). The pump is in, the machine is running, and it is making coffee, , , in a fashion. So it's time for a summary of the practical aspects, so anyone interested in converting their machines have the relevant information.
The FG304 pump is suitable for this application. The 4mm gearset seems ideal. The pump speed / flow rate is easily controlled, and at the slowest speed the flow does not exceed what would be required for a slow infusion. It can be easily installed in any orientation in, or for that matter, outside, of the machine. The pump is not completely silent, so I would recommend some form of vibration mounts, just to keep the 'chatter' away from the machine chassis. Likewise, it would be wise to route any flexible pipework away from other parts.
Plumbing the pump is is relatively straightforward. Note that some of the pumps are manufactured with NPT ports, not BSP. I am drawing the water from the machines water tank, and that works fine. I have no idea if you could plumb it in and what complications that may involve. No special or additional manifolds are required. No additional bleed, orifice, needle valves, flow control valves, etc, are required. The only thing you will need is a check valve somewhere on the output of the pump. Provided your OPV valve is operating correctly, and is adjustable, it should be fine. Please note that the manual recommends to avoid pressure spikes in the discharge side of the pump, so any valve downstream of the pump, including the grouphead solenoid valve, should only be closed after the pump has stopped.
Electrically, it is not too complicated to wire up. The information in the manual is easy to understand and implement, and the single potentiometer provides a very convenient and reliable means of speed control. The Meanwell LPV 24-100 power supply that Lyrebird recommended is more than adequate for the pump motor. I chose the simple path, and connected the power supply to where the vibration pump was previously connected. As Level3Ninja noted, when you switch the 240VAC supply to the Meanwell power supply, your pump will be delayed turning on and delayed turning off as the output voltage of the power supply builds and drops. This delay, which could cause spikes in the discharge line, is manageable by manually reducing the pump speed using the potentiometer prior to cutting power. Having said that, several people have recommended useful work-arounds and circuits which would solve this problem.
And finally, I've limited the scope of my project to the basics, and deliberately avoided the control of the pump via a pressure transducer, by a microprocessor, with a feedback circuit, etc. In doing so, I have not taken advantage of the the additional features and capabilities that these variable speed gear pumps provide. I'm sure that others could integrate the pump and it's electrical control into their machine far more professionally than I have, and I would encourage them to do so.
That's about it. I can't think of anything else, except that the technical support people at Fluid-O-Tech are quick to answer any emails, and seem more than happy to provide additional information. Oh, and there is heaps of useful information out there on the net - I'm still trying to catch up.
Cheers, Stavros.
It's time to wrap this thread up. It was initially going to be about a little 'project' to replace the vibration pump with a rotary pump, but then morphed into the installation of a variable speed gear pump, (along with all the associated flow control, pressure profiling, pre-infusion baggage). The pump is in, the machine is running, and it is making coffee, , , in a fashion. So it's time for a summary of the practical aspects, so anyone interested in converting their machines have the relevant information.
The FG304 pump is suitable for this application. The 4mm gearset seems ideal. The pump speed / flow rate is easily controlled, and at the slowest speed the flow does not exceed what would be required for a slow infusion. It can be easily installed in any orientation in, or for that matter, outside, of the machine. The pump is not completely silent, so I would recommend some form of vibration mounts, just to keep the 'chatter' away from the machine chassis. Likewise, it would be wise to route any flexible pipework away from other parts.
Plumbing the pump is is relatively straightforward. Note that some of the pumps are manufactured with NPT ports, not BSP. I am drawing the water from the machines water tank, and that works fine. I have no idea if you could plumb it in and what complications that may involve. No special or additional manifolds are required. No additional bleed, orifice, needle valves, flow control valves, etc, are required. The only thing you will need is a check valve somewhere on the output of the pump. Provided your OPV valve is operating correctly, and is adjustable, it should be fine. Please note that the manual recommends to avoid pressure spikes in the discharge side of the pump, so any valve downstream of the pump, including the grouphead solenoid valve, should only be closed after the pump has stopped.
Electrically, it is not too complicated to wire up. The information in the manual is easy to understand and implement, and the single potentiometer provides a very convenient and reliable means of speed control. The Meanwell LPV 24-100 power supply that Lyrebird recommended is more than adequate for the pump motor. I chose the simple path, and connected the power supply to where the vibration pump was previously connected. As Level3Ninja noted, when you switch the 240VAC supply to the Meanwell power supply, your pump will be delayed turning on and delayed turning off as the output voltage of the power supply builds and drops. This delay, which could cause spikes in the discharge line, is manageable by manually reducing the pump speed using the potentiometer prior to cutting power. Having said that, several people have recommended useful work-arounds and circuits which would solve this problem.
And finally, I've limited the scope of my project to the basics, and deliberately avoided the control of the pump via a pressure transducer, by a microprocessor, with a feedback circuit, etc. In doing so, I have not taken advantage of the the additional features and capabilities that these variable speed gear pumps provide. I'm sure that others could integrate the pump and it's electrical control into their machine far more professionally than I have, and I would encourage them to do so.
That's about it. I can't think of anything else, except that the technical support people at Fluid-O-Tech are quick to answer any emails, and seem more than happy to provide additional information. Oh, and there is heaps of useful information out there on the net - I'm still trying to catch up.

Cheers, Stavros.

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