400 gpm RO

[wlatrout]

Last spring someone posted a 3x400 gpm setup. I've searched throughout the forum and have not been able to find it. Does anyone know that post lies?

[maple flats]

Maybe it was 400 gpd, many small homemade RO's use a 400 gal/day membrane single or multiples.

[wlatrout]

Yes it was. It was 2 in series and one in parallel. Maybe another site, can't remember. Seems I use the term a lot these days. I may be senior but at least I'm on the right side of the sod. Gotta be thankful for that.

[maple flats]

Being a senior is not a detriment until the ravages of time take over. At 73, almost 74 I'm hoping to remain sort of OK for a while longer.

[DrTimPerkins]

It was 2 in series and one in parallel.

You probably mean two in parallel feeing another in series. The sap would flows through one of two membranes first (the parallel part), then the concentrate coming out of those membranes would feed the third membrane (which is in series with the first two).

[wlatrout]

Yes, would this be the best use of these membranes? Do you recall an article on how to plum these?

[maple flats]

I don't recall, but the plumbing should be straight forward. First go thru a pre-filter, then route to the first two membranes, using a tee, so the flow can go to either, enter the housings on the outer ports. Then at the exit, have permeate connected to the center ports on each and on the outer port exit join both using a tee and send that flow to the outer port on the third membrane housing. That 3rd one will then have an outer port exit for concentrate and a center port for permeate. All of the permeate lines can be joined using tees and sent to a collection tank. The last concentrate hose (the outer port exit will the need a needle valve of suitable size to match the high pressure pump you are using. In use, get good flow with the needle valve full open, then close it to regulate the flow from each. Many just try for what looks like equal flow from the permeate (the water removed) and the concentrate. Others add flow meters for a better idea of what is happening. Another added item which some add is a pressure gauge on the concentrate line after the last membrane and before the needle valve. Never restrict the permeate flow, just the concentrate.

[DrTimPerkins]

Yes, would this be the best use of these membranes? Do you recall an article on how to plum these?

That depends upon your goals. In general, a single standard membrane will max out at 4.7X the sap concentration at the stated flow rate (400 gpd processing rate I think is what you said, but this is hugely dependent on your pump pressure/recirculation/sap temperature/etc.). In practice this means taking sap from about 2% to about 8% assuming your system can achieve the proper pressures. If you put all 3 membranes in parallel, meaning they all process sap from 2 to 8%, then you'd get 1,200 gpd from 2 to 8% (again, assuming your system -- pumps, etc.) can handle it.

To bump up the concentration, you need to put membranes in series, so it would first do something like 2% to 8%, then the concentrate from that membrane(s) would go from 8% to maybe 15+% (again, pump and plumbing dependent). If you want to achieve the highest RATE of concentrate production, you'd probably go with 3 membranes in parallel. If you want the highest concentration, you might go with 3 membranes in series, but the flow rates would be very low. For a balance of good concentration level at decent flow rates with 3 standard membranes, then a 2 X 1 (series x parallel) probably makes the most sense. Somewhat depends on your membranes and pumps/recirculation/etc. also.

[wlatrout]

Thanks Dave and Dr. Tim. '
Going to get started on it for next season. It'll be quicker then think. Good info.