recirculation in ro

[squirrel]

I have an old ro with a piston type pressure pump. how it is plumbed is it goes threw the pressure pump then into a recirculation pump then from there it goes into the top of the first membrain out the bottom and into the top of the second membrain then to the concentrate tank. My question is would it be of any advantage to plumb in another recirc pump betwen the first and second membrains

[Sunday Rock Maple]

I don't know the answer, but is this a Coster? I have the same setup with only one membrane (Mark E8) and am thinking of adding a second. I get about 425 gallons total sap processed per hour with an input of 2% and an output of 7.5% --- wondering what that would be with 2 membranes (the manual doesn't show another pump though).

[spud]

I have an old ro with a piston type pressure pump. how it is plumbed is it goes threw the pressure pump then into a recirculation pump then from there it goes into the top of the first membrain out the bottom and into the top of the second membrain then to the concentrate tank. My question is would it be of any advantage to plumb in another recirc pump betwen the first and second membrains

It's my understanding that just adding another tower without another pump will give you half of what your first tower is giving. So if you have a 600 then it would be a 900GPH If you add a pump with the second tower then it is a true 1200 GPH. There are countless people on Trader that can help you much better then I can on this topic.

Spud

[wiam]

If we knew what your RO is maybe someone with experience with that machine could be more helpful. I doubt addin a pump like your talking about would help.

[wiam]

Brian, what pump do you have? My Memteck has a Magikist M-38 with a 3 hp I added 2 4" membranes to it this year so now I have 4. The first 2 were in series so I put the new ones in series parallel to the old ones. I gained about 75%. But now I have to run the high pressure valve almost all the way in. I think this means I am close to max flow for the high pressure pump.

[bowhunter]

William,

You are about out of pump, but you might need to watch the performance over time closely now. The flow through the membranes is now much lower than the original design and that means fouling is more likely. All the flow through the high pressure valve was recirculating through the original membranes before you added the last two membranes in parallel. Maybe you won't see any noticeable increase in fouling rates, but it's worth watching. Dow recommends a minimum of 2-3 gpm of concentrate flow for a 4 inch membrane so it looks like you're still ok. If my math is correct your current concentrate flow per side is about 2.5 gpm. This is based on a calculated hp pump flow of about 20 gpm.

[squirrel]

it is a coster ro with a majikist m-38 pump 5 hp motor and 2 8" membrains

[wiam]

William,

You are about out of pump, but you might need to watch the performance over time closely now. The flow through the membranes is now much lower than the original design and that means fouling is more likely. All the flow through the high pressure valve was recirculating through the original membranes before you added the last two membranes in parallel. Maybe you won't see any noticeable increase in fouling rates, but it's worth watching. Dow recommends a minimum of 2-3 gpm of concentrate flow for a 4 inch membrane so it looks like you're still ok. If my math is correct your current concentrate flow per side is about 2.5 gpm. This is based on a calculated hp pump flow of about 20 gpm.

My recirculation flow meter shows about 15 gpm. This did not change with the added membranes. I realize this flow is now split hopefully in half. So far have not seen much change in fouling. I have found I need to close valves on each"side" and more air comes out. This will increase flows. Washing concerns me more. I alternate sides when washing.

[wiam]

it is a coster ro with a majikist m-38 pump 5 hp motor and 2 8" membrains


I do not see a pump added between membranes helping

[wiam]

I also find it interesting to see how many of these older machines are still running. :)