Adding membranes

[Brent]

I have a 150GPH Airablo RO that has two 4" x 40" membranes. I'd like to get a little more performance out of it so I'm thinking about expanding it to 3 membranes.

First part of the question is, how much performance increase would it give if I just add the 3rd membrane without adding horsepower.

Second part: I'm thinking the 2nd and 3rd membranes should be in parallel rather than in series. If the third one is in series it will be like recirulating with 8% going in and maybe 12% going out, and of course the 3rd one will fowl up faster because of that. If I put the last 2 in paralell then both get fed about 4% and yield up about 8%.

Anyone with experience got any feedback on this idea ?

[wiam]

I have a 150GPH Airablo RO that has two 4" x 40" membranes. I'd like to get a little more performance out of it so I'm thinking about expanding it to 3 membranes.

First part of the question is, how much performance increase would it give if I just add the 3rd membrane without adding horsepower.

Second part: I'm thinking the 2nd and 3rd membranes should be in parallel rather than in series. If the third one is in series it will be like recirulating with 8% going in and maybe 12% going out, and of course the 3rd one will fowl up faster because of that. If I put the last 2 in paralell then both get fed about 4% and yield up about 8%.

Anyone with experience got any feedback on this idea ?

No experience but I am going to do the same thing.

Performance will depend on size of high pressure pump. Some are over sized from factory. Do you have any problems building to pressure now? On my very old Memtek (225 gph) with a piston pump I am going to try adding one membrane to the two 4" on it now. But I have been told that this pump will run up to four 4" membranes. I am going to run them all in series. If this works I will try another one later.

[Brent]

My system is supposed to run at 300 psi and does that now. The XLE membranes are supposed to be great performers at lower pressures and therefore higher electrical efficiency ... not a big deal for us for 100 hours a year, but if you're running a salt water system with several hundred membranes and a few thousand Hp. it makes a difference.

If the pressure drops to 250 with a 3rd membrane I'm thinking I'll get about a 20-30% boost in performance. Also if the second and 3rd membranes are in parallel they should not foul up so fast and I may/ hope to get longer runs between cleanings.

I suspect that the big performance drop on most systems that run with the membranes in series, comes when the second membrane gets fouled faster because it is getting concentrate at double the % of the first membrane. Lots of theory and hoping here.

I've been in a room with one of those piston pumps .... I hope you're using hearing protectors. I've lost half my hearing and it ain't fun.

[wiam]

My RO shed is built into the ground about 30 feet from sugarhouse. Still can hear when it shuts down.:rolleyes: Needs no heat to keep from freezing and limits noise. I have xle's and run them about 450.