RO Pump

[MT Pockets Producer]

We are setting up an RO with one 4x40 membrane this year and probably expand to two in the future. Looking at either the MES or the XLE. Can anyone tell me if the multistage pump in the attached link would work ok or would the flow /pressure rates be too high and cause issues for a small unit? 10GPM/315 PSI max and will be using flow meters. We were originally planning on a procon pump but I have a line on a multistage that I can get cheaper than the procon, motor,adaptor etc. Thanks in advance.

https://www.pumpproducts.com/myers-10mpb100-02-high-pressure-booster-pump-mpb-series-hp-115-230-volts-phase-10-stages-npt-discharge-npt-suction-10-gpm-best-efficiency-flow-15-gpm-max-440-ft-max-head-stainless-steel-body-p-544002.html

[mellondome]

It will work fine with 1 membrane. Should work ok with 2, but might be a little low on flow. You will need to front it with a lift or supply pump.
Nice thing with using a multistage is you don't need a wash tank heater.

[MT Pockets Producer]

We will be feeding the multistage with a Grundfos well pump capable of about twice the GPMs. Regarding the wash tank, I,m assuming the proper set up would be to use a high temp shut off to regulate the pump/temp in the tank so it does not damage the membrane by getting too warm?

[wiam]

We will be feeding the multistage with a Grundfos well pump capable of about twice the GPMs. Regarding the wash tank, I,m assuming the proper set up would be to use a high temp shut off to regulate the pump/temp in the tank so it does not damage the membrane by getting too warm?

That will work. Mine is installed in a T after my feed pump. That way I can keep track of permeate temp when doing membrane performance test.

[Tweegs]

The pump will be plenty for two membranes if you put them in series rather than parallel.
The only thing I see as a concern is the amount of pressure it is capable of.
The membrane housings typically available on ebay can only take 300 psi.

If you choose to go with one of those housings, consider a high pressure cut off in your circuit.


The high temp cut off is up to you.

In either case, high temp or high pressure, it’s going to depend on how you run the unit.

If there is a chance you will become distracted or want to wander away, put the automatic safeguards in place.
Flip side is these devices add complexity to the control circuit and the more complex it is, the greater the chance for failure of the circuit.
Proper design and quality components are key.

Manually checking gauges and temp sensors work just as well as the auto devices, you just need to be sure you are always available to do it.

Your call.

[MT Pockets Producer]

The pump will be plenty for two membranes if you put them in series rather than parallel.
The only thing I see as a concern is the amount of pressure it is capable of.
The membrane housings typically available on ebay can only take 300 psi.

If you choose to go with one of those housings, consider a high pressure cut off in your circuit.


The high temp cut off is up to you.

In either case, high temp or high pressure, it’s going to depend on how you run the unit.

If there is a chance you will become distracted or want to wander away, put the automatic safeguards in place.
Flip side is these devices add complexity to the control circuit and the more complex it is, the greater the chance for failure of the circuit.
Proper design and quality components are key.

Manually checking gauges and temp sensors work just as well as the auto devices, you just need to be sure you are always available to do it.

Your call.

We had planned on the high pressure shut off in our original plans. As far as the high temp that may be easier to do manually as you suggest. You mentioned the pump will be sufficient in series vs parallel. I see some using a procon or fluidotech rated at 5GPM or so on two membranes in parallel with decent results. How would that differ from the multistage at 10 GPMs? If I understand correctly from reading other threads series would bring the sugar content up higher in one pass than parallel but using the smaller pumps there would not be enough flow/ pressure on the second membrane to be efficient. Just want to be sure I am thinking correctly.

[wiam]

We had planned on the high pressure shut off in our original plans. As far as the high temp that may be easier to do manually as you suggest. You mentioned the pump will be sufficient in series vs parallel. I see some using a procon or fluidotech rated at 5GPM or so on two membranes in parallel with decent results. How would that differ from the multistage at 10 GPMs? If I understand correctly from reading other threads series would bring the sugar content up higher in one pass than parallel but using the smaller pumps there would not be enough flow/ pressure on the second membrane to be efficient. Just want to be sure I am thinking correctly.

Unless you have time to stand beside your ro while it washes you will appreciate a high temp shut down.

[mellondome]

With 4x40 membranes, you will find that there is a huge trade off between higher concentration and flow/plugging rate. This is because the isn't the ability to recirculate well with these small units. Most of these membranes have a max surface flow rate @ about 14 gpm.
With a multistage turbine unit, you don't have to worry as much about over pressuring the housings as you would with a positive displacement unit like a procom. To even get to 250 psi, you need a boost pump pushing 60psi and a turbine pushing 190 psi and everything be deadhead. In reality for the best performance and water removal you will be operating in the 150psi range. And there is no worry about over pressuring the housing. I wouldn't bother with a high pressure shut off in this type of build.... only temp shutoff for washing.

[Tweegs]

Our operations are almost identical in size, with similar intentions for the RO build.

The numbers I give below can serve as a baseline, jumping off point for two XLE-4040’s in series.

Somewhere, and I can’t tell you where, I came up with 3 GPM across the membranes, at pressure, was the minimum needed to help prevent premature fouling of the membranes.
Right or wrong, that’s the number I stuck with.

I started with a 4 GPM Procon pump and could only get to 175 psi before dropping below 3 GPM across the membranes, so I stepped up to a 6 GPM Procon pump.
Here I was able to get to 225 PSI, but I’m getting close to the limit of my 1 HP pump motor (need to go to 1.5 HP).
This is why I suggest your 10 GPM pump is adequate for membranes in series.

With the 6 GPM Procon running at 225 PSI and cold sap, I start out making 1.7 GPM permeate and end my batch processing at around 1.5 GPM permeate (due to fouling).

We need 125 gallons of sap to fire up the evaporator. That amount reestablishes the gradient and pushes syrup out of the evaporator.
As such, we concentrate whatever amount of sap we have down to 125 gallons.
On a good day we’ll have 600 gallons to process. The RO will have that 600 gallons ready to go in about 5 hours.

Our M.O. is that I start the RO when I leave for work in the morning (6 AM).
My wife fires the evaporator when the RO has finished batch processing (~11 AM).
I take over the evap when I get home from work.
It’s a rare day we are still boiling past 6 PM.
Most times we’re shut down, cleaned up and eating dinner by then.

Because the RO runs unattended, high and low pressure cut offs were a must.
Since my to-do list never seems to get any shorter, babysitting a wash cycle ranks pretty low. Therefore, temp monitoring is also a must.
This can be done with a PID controller and an RTD, but I find those cheap PID controllers frustrating at best (accuracy, drift and awful instructions).
I use a microcontroller instead (Arduino).

If you have any programming experience at all, the micro’s will be a breeze and I can point you down that road.
Even if you don’t have experience, the learning curve isn’t terribly steep, but steep enough that I would suggest a different path for this coming season.

[bowhunter]

Dow recommends 3-4 gpm minimum concentrate flow out of a 4 inch membrane which is probably where you came up with 3 gpm.

[MT Pockets Producer]

Thanks for all of your replies. I think I am getting a better understanding and realize I did not consider the performance curve these pumps have. So what I have gathered is if I have a pump that is rated for 10 GPM at zero or a low input pressure, the GPMs go down as the pressure goes up making it about a 5 GPM pump at 150 PSI. But if I introduce a feed pump that produces 50 PSI I should see numbers that are about 5 GPM at about 200 PSI ? The pressure would be satisfactory for an XLE set up but I would probably need to consider a little more flow if I were going to go with 2 membranes in parallel? Am I understanding correctly ? Thanks.

[bowhunter]

I would highly recommend the ProCons They are very reliable and they have a very flat pump curve. For example a ProCon pump rated at 10 gpm will deliver 10 gpm at 250 psi and only slightly more flow (10.2 GPM) at 50 psi. With 320 taps, I think one XLE 4040 with a 6 gpm ProCon pump should handle your needs most of the time. I'm sure your evaporator will handle 20-25 GPH of concentrate.