RODI
- Thread starter jtl
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JoshH
Tank Status: Wet...ish, growing things....
Hi Russ,
You folks tried to help me on two occasions with no success so I see no reason to go for three and waste your time. The last time we spoke I replaced the membrane housing on the chance it may have a hairline crack. I reseated the membrane, we talked about pressure and temperature. In the end the only thing that works is to replace the membrane to save on DI and that gets to be about a toss up in cost. I was surprised that I tried two different capillary restrictors and neither one worked any better than my regulary 550 inline restrictor. I guess the good news is that I only use about 75 gallons of RODI per month
If you don't mind me asking, you used a capillary flow restrictor correct? Did you cut them to the right length to allow for a 1:4 product to waste ratio?
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jtl
Well-Known Member
I did not change the length of the restrictor because it was sized for a 75 gpd membrane but you bring up a good point. Maybe I should trim a little off to increase the flow although it is pretty short as it is.
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jtl
Well-Known Member
Yes, I had it in my box of spare parts but it had never been used.
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jtl
Well-Known Member
Wouldn't that be something if I had this on wrong after looking several times at diagrams online when I set it up. Anyway. There are two ports coming out of the membrane housing. One is centered and one is off set. I have the drain connected to the one that is offset and the water going to the DI coming out of the center one.
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jtl
Well-Known Member
Certain, I just double checked.
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jtl
Well-Known Member
That is correct, strange as it is.
Then something is wrong. Does the capillary tube on the blue restrictor have a kink in it? Is the capillary tube partially blocked with scale?
If both restrictors are functioning properly, and if all other variables are held constant, there is no way for a 735 restrictor to have less flow than a 550 restrictor.
If both restrictors are functioning properly, and if all other variables are held constant, there is no way for a 735 restrictor to have less flow than a 550 restrictor.
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jtl
Well-Known Member
I actually have two blue ones and they were both brand new in the package. They are not a lot worse than the 550 but close, certainly not any better. The 550 is about 1.25:1 and the 735 is closer to 1:1.
That's not possible given what you've told me, so something else is happening/going on. The blue ones allow MORE flow to drain - they are less restrictive. Maybe you want to try a 100 gpd restrictor.
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jtl
Well-Known Member
So today I had some time and trimmed the capillary tube. No noticeable change. Than I got to thinking that maybe the problem is the output of RODI not the waste. I have a 75 gpd membrane and when I measured the RODI water being produced it was 135 gpd. I recall this being the case a year ago and I replace the membrane and the enclosure since then. Just another piece of the puzzle.
Higher than expected permeate flow could be from a cracked RO membrane housing, a failed membrane, higher than spec temperature and pressure.
Is the TDS of that RO water bad?
Is the TDS of that RO water bad?
