Twodose
Active member
I have a single 4x40 ro membrane. What should the pre and post membrane pressure be. I just replaced one and it is 120 psi in and out. Does that sound about right?
RO membrane pressure...
- Thread starter Twodose
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spf8298
Member
Don't mean to hi-jack your post, but I have a question along the same lines. I have a single 4x40 ro membrane and I'm not sure if I need a 150 psi membrane or a 225 psi membrane....I have a booster pump that forces the water through the membrane. Hopefully someone chimes in.
Twodose
Active member
I don't think that there is a difference between the membranes, the pressure should be able to be adjusted on your RO setup, there should be a balanced pressure regulator or something like it that you can adjust the pressure.
Greg Pack
Wash Weenie
it depends on the membrane and pump arrangement. Some are designed to work lower pressures. Most systems are deaigned to run in the 175-200 psi range. There are high efficiency membranes that work as low as 100-130psi or so. I adjust mine to reject a little more than it makes and leave it there.
MEP001
Well-known member
To get the maximum life from a membrane, the product/reject flow needs to be set properly. A lot of older systems don't "recycle" some of the reject and should run at 3:1. If the pump isn't sized properly you might not achieve 200 PSI unless you close off the reject more which will foul the membrane faster, for example a Procon on a 3/4 HP motor won't move enough water to run 200 PSI on a 3:1 system. You may have to go to the manual or figure out the layout of the system.
Twodose
Active member
How often should a single 4x40 RO membrane be set to backwash?
MEP001
Well-known member
AFAIK there's not a real number, some systems never do, some do on a timer every day, some do at the end of every cycle, some even do it with RO water from the tank.
For accuracy sake, it's not a backwash, it's just a flush with no pressure, and in my opinion it doesn't do any real good after seeing and working on hundreds of different systems I can't tell any difference in membrane life or output quality with systems that have a flush. Incoming water quality is what's important, must be soft and chlorine-free.
For accuracy sake, it's not a backwash, it's just a flush with no pressure, and in my opinion it doesn't do any real good after seeing and working on hundreds of different systems I can't tell any difference in membrane life or output quality with systems that have a flush. Incoming water quality is what's important, must be soft and chlorine-free.
