How many membranes?

[Minnesota Tapper]

I currently run a procon 660 with 3 4x40 membranes in series. Each membrane removes about .6 to .8 gpm of permeate. I have a ton of extra sap flow over the membranes. How many more membranes can I add in series? My 660 pump flows 11gpm. Currently when I'm using the ro I have 8-9 gpm of concentrate coming out and 2-3 gpm of permeate. I typically process 1000-1500 gallons a day and don't have any fouling issues. But I'd like to speed things up a bit by adding membrane(s) and not foul up too soon. How many membranes can I run before I don't have enough sap moving across the membrane surface to keep if from prematurely fouling? Thanks for any advice!

[maple flats]

Maybe try 2 pair of parallel lines of 2 in then combine the last for, It should work fine

[BAP]

Something is not right if you have way more concentrate coming out than permeate. A properly set up RO should be just the opposite than what you are posting. If what you said is true, then I would work to correct that before trying to add more membranes.

[bmbmkr]

I have a 660 and 4 4x40's in series. I could get 3.5 GpM of permeate at 175, which is on par with what you said yours was putting out. I used to run my 330 and two membranes up to 290 psi, but when I put the 660 on and two more membranes last year, it kept blowing a cap at around 150. I changed some of the plumbing for this season, and sure enough blew a cap at 200 while testing with permeate at the beginning of this year. I had 3/4" street elbows with a 6" nipple connecting the 2 & 3 vessel, and looking at it closely when I removed both of them, one cap had the threads tapped crooked. It was not cross threaded, the threads aren't square to the cap. So I took off the elbows and put in 3/4" NPT-3/4" hose barbs, and a short piece of hi pressure hose bent in a u shape. I still didn't take it past 200, but was able to recirculate after the first pass of 3.5P-7.5C and get 2.5P-1 C while recirculating and feeding my 45 gph evaporator. For next year, I'm puttin a single 8x40 on. 1 8x40 will perform better than 5 4x40's and with a while lot less plumbing.

Last year I had 2 sets of 2 in series, in parralell, split off the pump with a wye fitting and I was able to get 7.5 GPM permeate/ I also kept my old 330 and tried to use it as a recirculation pump. Now that is 16.5GOM total, and 4x40's max is 14 gpm, so that's whay I split into two pairs thinking it would only run 8.5 in each. I had all kinds of hiccups, and did away with that this year, finally just replumbed the recirculation loop to feed off the concentrate outlet of the ast membrane back into the 660 intake. I was still gettin 11 gpm across the membranes which wow this is the first in 5 years i didn't have to stop squeezing and let pressure down and do a flush halfway or more times as the membranes fouled. I'd set pressure on 175 and let her run and the pressure would stay steady for hours. I was really happy with it until a bearing went out on the 2 hp motor I got from Vevor. Last year I had a 3 hp chinese motor and that one only lasted ten hours. I'm goin to have to get a Leeson or Baldor for next year. The 1 1/2hp Leeson I had pushin my procon 33 probably has 200 hours on it.



Are your cup selas facing the right direction?

[Rselleck91]

Personally I would ditch the 4” membranes. 1 8” vessel is equivalent to 4 at 4”. A multistage booster pump with the membranes in a loop keep the sugar from fouling.

[Minnesota Tapper]

Thanks for all the responses! I agree with going to a single 8". But I have bought extra membranes each year just in case I needed them mid season in an emergency. So now I sit here with 5 brand new mes 4" membranes that I've bought over the last couple years. Figured I'd use these up first and then I'll go 8".