needle valve on recirculation loop and rincing procedure

[sweet spot maple addict]

Good afternoon
I have a single 4x40 on which i would like to plumb a recirculation loop.
I have read all threads and i have seen some with two 3/8 inches needle valves ( concentrate and recirculation)
I understand they are a lot more efficient to adjust a small flow of .5gpm on concentrate , but the hole inside them is about
1/8 inch . When rincing i dont want to put restriction on the membrane to increase flow , so even fully open are these valve
putting to much restriction on the membrane as to increase pressure?
I usually rince at about 30 psi , threshold pressure switch.
Would you have an example of an inline flowmeter for .5gpm ?


Pierre
200 taps on 3/16
A wife that understand the basic of sugar making and the complexities of the sugarmakers !!!
And a good Shetland dog named Brix.

[SeanD]

Typically, when rinsing, the recirculation valve is shut and the high pressure valve is wide open to put the highest flow possible across the membranes. Is that answering your question?

[sweet spot maple addict]

Thanks Sean

Now i dont have recirculation , i have a ball valve as restriction valve on the concentrate to adjust pressure and permeate /concentrate flow to 5 to 1 .
I rince and wash with ball valve almost fully open (about 30 psi)
My concern is that the needle valve fully open has an little hole of about 1/8 of an inch , so if this is use to regulate my concentrate along with the recirculation loop,
when i fully open the needle valve , and close the recirculation for rincing , will that small hole exert to much restriction so as to limit the flow, increase pressure, and
decrease rince capacity ????

Pierre

[halladaymaple]

Woodville maple has it right. Close the recirc valve on rince. No need to recirculate back into the membrane. Flush with copious amounts of water at feed pump pressure.

Dh