New 4x150 series RO - Flush and Pressures

[bryankloos]

Hey All,

Hoping you can all help.

I built a 4x150 RO based on plans here and on Mattatuck.
I installed the new membranes this evening and started flushing with slightly warm softened well water.
Even with a good amount of restriction on the concentrate line I only get up to maybe 70 psi. The pump is an 8852.
Should I see higher PSI with just a water flush?
If I put a needle on both permeate and concentrate lines I can get the pump up over 125 psi, so I know the pump is functioning.
Will I see greater pressures with SAP?
This is my first year with the RO and I'm a newby.
I don't want to start concentrating SAP if the system is not functioning properly.
Any suggestions?
Thanks,
Bryan

[bryankloos]

Heres a pic of the setup... Pump and Filter on the backside

IMG_4849.jpg

Those pink push connectors are check valve... Maybe thats the problem?

[bryankloos]

Nevermind...
Seems cold sap and a purged system are much different than warm softened water.
I'm currently running at 125psi with concentrate at 6%.
I"m assuming I'm about 1.5% starting as I have mostly reds.
This thing is cool!

[bowhunter]

Cold sap can reduce the permeation rate by as much as 50% just because of the temperature. Also as the sugar content goes higher the permeation rate decreases at the same pressure. You have to use pressure to overcome the higher osmotic pressure caused by the higher sugar concentration.

[hodorskib]

Mattatuck Madness is my site and you are correct - you will not see pressure until you are processing sap. Good luck.

[SyrupHog]

Cool setup and glad to hear it’s working now. I’m looking at building the same kind of setup for my 100 taps. Is there a reason to go with, say, four 100GPD filters vs one 400 GPD filter instead? I’ve got the same pump on order from Amazon, but have yet to order the filters/housings. Thoughts?

[DRoseum]

The smaller the membrane, the slower the flowrate. Either your membranes or your pump will be limiting factor on flowrate at operating pressure depending on your configuration (series vs parallel vs combination).

I put together a post on some basic principles to consider when building an RO as well as details on one I designed and built. With approx 40 - 45 degree sap I have been able to process nearly 20 gallons (5 gals of quadrupled concentrate and 15 gals of permeate) in a little over an hour. This goes down with temperature - membrane performance decreases with temp.

https://www.sugartree.run/2020/01/di...-hobby-ro.html

[SyrupHog]

Thanks for that! Great site, very clearly written and easy to understand with good pics. Very helpful.

[vernedog]

keep in mind some filters state 400GPD but spec are based on 100psi and 77 degrees. The Amazon ones are an example. Now on the other hand filmtec 100GPD filter are rated for 50 psi and I think 77 degrees also.. so the filmtec 100 GPD produces over 200GPD at 100 psi. If you look up the filter on amazon or DOW they show charts with psi and temp . From what I see You loose about 50% at 40 degrees. If anyone is interested I just found the filmtec TW30-1812-100 @ wallmart
for $16. I ordered a few today as I have the 1812/2012 canisters.