water pump for coffee van

[morris]

Hello all, hope I am posting this in the right section.

I am in the process of building a coffee van, my coffee machine is a 2 group Faema E98. I'm looking at 12v water pumps to pump from the water storage tank to the water filter and coffee machine. I am getting a bit confused between pressure and flow. One of the pumps I am looking at is 3.5 litres per minute flow rate and the other is 12.5, but both are 35psi pressure. The 3.5 one has a 10mm pipe inlet and outlet while the 12.5 one has 20mm pipes. The 10mm pipe just looks very small to be feeding the coffee machine.

Does anyone have any experience on what flowrate or water pressure I should be going for?

Thanks in advance

[beccarivers]

A 35 PSI pump will supply water at just below standard household pressure and so is a good booster for your coffee machine pump. Unless you are running a kitchen sink tap as well as your coffee machine you won't need the 12.5 litres a minute. The Escaping Outdoors FL2202 is a reliable pump which will supply 4.3 lpm - I have used it in my set up for a while now.

[Dick83]

Hey morris I'm guessing you already got your answers you needed as you posted this in 2014 and you've only just got a couple of replies basically both you pumps will operate @ 35 psi you receive a higher flow rate on one due to the larger diameter pipe which allows a greater volume of water to flow through the pipe work

Regards Dicky

[MrJack]

Hey morris I'm guessing you already got your answers you needed as you posted this in 2014 and you've only just got a couple of replies basically both you pumps will operate @ 35 psi you receive a higher flow rate on one due to the larger diameter pipe which allows a greater volume of water to flow through the pipe work

Regards Dicky

This is not how a pump works.

The operating point (that is, the discharge pressure and flowrate it operates at) depends on the resistance of the downstream system:
- With no resistance, it will operate at a very low discharge pressure, at the maximum flowrate.
- With a very high resistance (or dead headed) the flowrate will be very low, and the pressure at close to the max discharge pressure of the pump.

The discharge nozzle represents a tiny fraction of the downstream system resistance, and in many cases the pump suction is actually more important.