Recirculation Pumps

[danno]

My RO does not have one.

Would a shallow well jet pump work:
http://cgi.ebay.com/Wayne-Cast-Iron-Shallow-Well-Jet-Pump-1-2-HP-SWS50-NEW-/130447339816?pt=LH_DefaultDomain_0&hash=item1e5f447128

Would I just add it in-line between the high pressure pump and the vessel?
I'm not really understanding the technology. Wouldn't the HP pump damage the circ pump by placing so much pressure on it? Wouldn't the circ pump reduce the pressure of the sap entering the vessel? I'm not sure what the circ pump does, that the HP can't do - in terms of keeping the membrane cleaner. I'm confused, please help me understand.

[mapleack]

My RO does not have one.

Would a shallow well jet pump work:
http://cgi.ebay.com/Wayne-Cast-Iron-Shallow-Well-Jet-Pump-1-2-HP-SWS50-NEW-/130447339816?pt=LH_DefaultDomain_0&hash=item1e5f447128

Would I just add it in-line between the high pressure pump and the vessel?
I'm not really understanding the technology. Wouldn't the HP pump damage the circ pump by placing so much pressure on it? Wouldn't the circ pump reduce the pressure of the sap entering the vessel? I'm not sure what the circ pump does, that the HP can't do - in terms of keeping the membrane cleaner. I'm confused, please help me understand.

Danno, first check out Teuchtars diagrams of his homemade RO here :http://mapletrader.com/community/showthread.php?t=4085&page=2 This should help with understanding flows through an RO with an external circ pump, I know it helped me. A shallow well pump like you were looking at won't work because of the pressure, the circ pump has to be able to withstand the operating pressure of the machine. As to how circ pumps make a difference, here's my take. On a machine like yours without a circ pump, the high pressure pump pushes sap into the membrane housing on the concentrate side. You've got a control valve to set the pressure by restricting the output flow. While this doesnt completely stop sap flow, it slows it way down, so the sap is almost "sitting there" under high pressure against the membrane. This allows junk that the prefilter didnt get and minerals, etc to get pushed into the membrane clogging it. A circ pump gets plumbed in so as to create a pressurized loop with sap flowing along the concentrate side of the membrane rapidly, keeping the junk suspended and keeping the membrane cleaner. This "loop" would go from the concentrate output, through a T where the output valve would be, onto to the circ pump, then through a check valve to another T where the highpressure pump would be adding sap to the system. This keeps the sap moving along the membrane instead of sitting there.
I hope that helped.
-Andy

[brookledge]

I do not think that that pump would work for a recirculation pump. First of all you don't want cast iron since it will allow rust.
Secondly it need to be able to hold up to the high pressure that the membrane is under. The pump does not have to be real powerfull since both sides of the pump are high pressure. just need to be sure the seals in the pump can withstand very high pressure.
keith

[WMF]

This is why the CDL machine with the recirc pump inside the membrane housing is quite revolutionary - no seals to leak externally.

Just the seal for most recirc pumps is a couple hundred dollars and usually won't be found locally.

Finding a pump head that has a working pressure of 400-500 psi is tough $$ .

[danno]

I've been researching pumps and having difficulty finding one that is:

1. stainless
2. can withstand high input psi (most centrifugal's max out at 200)
3. can generate >10 gpm

If anyone has an external recirc pump or just generally knows pumps and is willing to give me the make/model no. I'd appreciate it.

My RO is a 240 gph, 3 hp/4gpm HP pump, 4 4" vessels.

Thanks

[mapleack]

Procon series 6 pumps are stainless, 250psi rated and with the right HP motor will do 600 gph. Someone with more RO knowledge could sound in on this one, I don't think you'd need a motor rated to do 600gph, since your feed side would already be at high pressure.

[metalhead62]

hello i am new here but have been reading alot of the threads on ro's trying to c if i can put together a cheaper ro type thingymabob read all brents threads on the merlin maybe a little small 4 where i want to start 200-300 taps i have buddys doing maple but no ro s tried to start a thread a while back but not alot of response i can understand that as some dont know or cant explain and im pretty thick but i did get a couple trying to help and i think danno was 1 here is my ? / thought so i could use a pair of procon pumps run a250psi300gph pump(pump1) as my main feed into the input side of my housing t off the concentrate out side run that into a second procon 250psi300gph pump (pump2)back to ?a second t on the output side of the housing ?( so isnt sap tring to go out and in the same t)and then i get pretty thick again loli think i lost myself help maybe no more sap then i would have i could just run the procon pump in and be done by the time it would slow down that much a single pass though a single 4"would get me what maybe 4 or 5% cut my boil time in half