Membrane Pressure

[ennismaple]

What pressure do you guys normally run your RO membrane pressure at when you are concentrating. I know we can go to 500psi with ours but that high can cause problems. I've been told by some people to keep it to 300psi.

What pressure do you concentrate at?

[Russell Lampron]

I have always ran mine just under 500psi. I am going to recirculate my sap this season and keep it in the 300psi to 400psi range. The lower pressures add to the membrane life so if you can get enough flow at 300 to do what you want run it there.

[Teuchtar]

I keep mine at about 300, with a feed flow of 6gpm. I found raising the feed pressure will yield more permeate, but the membrane will clog faster, needing more frequent flushes.
This year, I am adding a bigger recirculating pump after the pressure pump. This will raise the recirc flow within the membranes to 16 gpm. According to the Dow Flimtec manual, a high recirculation flow is more effective than high pressure (above 300).
Net feed flow will remain around 6 gpm.

[maplwrks]

Most ROs have a high pressure shut off at 500 psi. I like to run mine at 200-300 while recirculating and usually 350-400 while on my final concentration.

[PATheron]

Mike-What do you try to concentrate to before you start sending it to the head tank? Theron

[maplwrks]

When I can get 17% or higher, I run it into the tank.

[sapman]

I have an Airablo machine that only concentrates to about 12%, and will only build to about 300psi. But I assume I could recirc. back to the sap tank like many do and get it considerably higher, right? Do you think this would kill the membrane pretty quickly? It's a 5 or so year-old Fluid Systems, which are wound very tightly I'm told. Sometimes I get confused whether you guys are talking about doing this, or referring to the recirc. pump on your ROs.

Thanks,
Tim

[Russell Lampron]

Sapman,

We're talking about recirculating it back to the sap tank. Keep the concentrate flow high when doing this. All you want to do is remove water. The high concentrate flow and low pressure are easy on the membrane. You can run it around 200psi if you want.