With a little help from my friends !!!

[sweet spot maple addict]

Hi folks
I have almost everything i need to plumb a poor man recirculation loop on my
single 4X40 post , but the needle valve still confuse me !!!!
Could someone tell me what they have use as needle valve on the concentrate side ??

Would be appreciated

[Greg MacWilliam]

You need 2 high pressure valves, the needle valve for the out going concentrate and a second high pressure valve in your recirculating line assuming you are recirculating to the low pressure side of the pump

[carls47807]

We use a stainless needle with 1/2" npt fittings and a 5/16" internal bore. This seems to give good precision on the recirculation side. Any high pressure valve will work, but a gate valve or ball valve will be hard to dial in. See our schematics and plumbing detail here:
https://www.therobucket.com/wp-content/uploads/2021/09/Single-Post-Parts-List.pdf

[sweet spot maple addict]

Thanks a lot for the schematics , this is what i am plumbing.
Could you send me the specs / links of the valves on the upper cap schematics , specially the needle valve with 5/16 internal bore
Thanks again

[Urban Sugarmaker]

I use 1/2" NPT thread stainless needle valves. Concentrate comes out of the membrane and into a tee. The concentrate goes into each needle valve - one to the flow meter and the other to the recirculation line back to the high pressure pump. Start the RO with the valves full open and close them down together to get the pressure and concentrate flow you want. I find that I have to fiddle with them initially to get close to a normal operating pressure of 200-250PSI. That is, you start closing both and balancing system pressure with the recirc valve as you close the concentrate valve until you are at the desired flow. It's just a balancing act at first because as pressure rises you will have to keep dialing back the recirc valve (open it) as you dial in the concentrate flow. At that point the concentrate needle valve will finely adjust the concentrate flow and the recirculation valve will finely tune your system pressure. Works great!

I typically concentrate at 50 gph to keep up with my evaporator feed rate and permeate runs around 0.9-1.2 gph depending on temperature and membrane condition. Using a single XLE-4040 you can slow this down enough to get 7-8 brix concentrate at 11-13 gph. The rest of the fluid is being recirculated and that's why you can do it this way in one pass. It's just much slower.

I got my valves from https://www.directmaterial.com/stainless-steel-316-needle-valves-10000-psi

[carls47807]

We sell the recirc valve for $40. You could use it for both, the concentrate and recirc. As a concentrate valve, the system will run around 40psi with the valve wide open. Shoot me an email if you want more info, sales@therobucket.com.

[sweet spot maple addict]

Thanks folks ,really appreciate the info
Last year my 4X40 did OK
But for next year i would like to plumb a recirculation loop to match
my evaporator at 30 gph at whatever brix i get .
I use to rince at about 25 psi ( low pressure switch treshold ) my concern is that
the concentrate needle valve even fully open would exert to much pressure for an efficient rincing procedure ( highest tengential flow possible)
But i guess that a valve with a 5/16 port which exert 40 psi when fully open should be ok.
Do i read numbers correctly with 50 gph of concentrate and .9 to 1.2 gph of permeate removed ?
thanks again

[Urban Sugarmaker]

Do i read numbers correctly with 50 gph of concentrate and .9 to 1.2 gph of permeate removed ?
thanks again

Actually 54 gph at 0.9gpm...correct.