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4040 RO Membrane help

JetMac

New member
Hello all, thanks for the add.
I hope this post is not duplicated and allowed. I do not operate a car wash, but this forum is the only place I've found where the 4040 is discussed. I have multiple issues with my residential well water, sediment, bacteria, methane, and salt intrusion. I have a fix in place for everything but the salt. I installed a BW 4040 membrane, and I have a couple questions. First, after flushing I began closing the wastewater valve and it back pressured my system to the point it broke a threaded PVC coupling and blew out a section of the PVC pipe. I have a 200psi gauge on the supply just upstream of the RO and the gauge was buried. I was running a boost pump at the time and supplying 120psi before I began closing the waste valve. I disconnected the boost pump electrically and fixed my broken connections and opened the water supply again supplying only well pressure (40-45psi), it immediately back pressured and buried the needle again. I removed the membrane and flowed water through the housing and everything worked as it should. Secondly the flow is pretty low. I have the wastewater open enough to hold pressure around 110psi, but the clean water flow is less than a gallon per minute. I haven't measured the waste flow as of yet.

My thought is that my flow rate being supplied to the membrane through 1" PVC is too much and is causing the back pressure. As a result, I am sending too much water through the waste stream which is why my clean flow is so low. So, here's my question, is there a way I can reduce flow to preserve my plumbing? I was thinking about installing another housing/membrane and splitting my supply between both filters? Would this lower my flow enough? Is there another method to lower the flow rate?

sorry for the lengthy post, any help would be greatly appreciated. Thanks.
 
As your question is one that comes up in car washes, I'll jump in here.

In general, do not use the flow restrictor/needle valve on your concentrate to achieve any particular pressure. Use the valve instead to achieve a particular flow. In order to do this you'll need a flow gauge on the concentrate. Do you have one?
 
Yes, I am doing this myself. I tried contacting several different suppliers/water filtration companies but when I explain my issues and what I have done so far they stop replying.
 
When you say concentrate, are you referring to the water supply to the RO?
No.

Here's some RO-related jargon for you:
FEEDWATER: The water coming to the RO system inlet. Typically this water has been pretreated to remove hardness (by a softener) and has been treated to remove chlorine or chloramine (by a backwashing carbon tank).
PERMEATE: aka - "RO water." This is the water low TDS purified by the RO membrane.
CONCENTRATE: aka - "waste water" or "flush water" or "brine."
 
There's not enough profit in the parts to cover design of a one-off system. You'd be better off buying a system
I can understand that. I'm just not able to afford that. I'll just keep plugging along until I exhaust myself. If I have to I'll revert back to my previous setup and continue to buy water for drinking and cooking.
 
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