Simple RO Questions

[pete3046]

Hello,
It's my first year with a Leader micro RO and I'm getting ready to process sap hopefully next week. I did a 125+ gal rinse last night and I'm going to my hot wash/alkaline wash and a final rinse tonight and had a few questions.

1. The manual says that the required ph is on the membrane data sheet. My data sheet says ph of up to 12. Does that seem correct?
2. Also, if I do not process enough sap to generate enough permeate to support a full desugar/rinse/wash/rinse cycle, can I just short each cycle? I would potentially need over 250gal for those cycles, which would require around 400gal of initial sap.That is kinda of on the high end for me.

Thanks,
Pete

[DrTimPerkins]

1. The manual says that the required ph is on the membrane data sheet. My data sheet says ph of up to 12. Does that seem correct?

The proper pH depends upon the membrane. Go with what it says. If it states pH up to 12....that's good. You may not actually get that high (it is UP TO) depending upon the soap you use (note that RO soap is highly caustic to skin/eyes...take necessary safety measures).


2. Also, if I do not process enough sap to generate enough permeate to support a full desugar/rinse/wash/rinse cycle, can I just short each cycle? I would potentially need over 250gal for those cycles, which would require around 400gal of initial sap.That is kinda of on the high end for me.

Check your manual instructions, but if a soap wash is needed you normally would:
desugar, wash, rinse (without an intermediate rinse after the desugaring).

Some people do not wash after each concentration cycle, but instead check the flow rates. If flows are still good, you would:
desugar, long-rinse (no soap wash)

Typically your rinse would be with a volume equal to your RO rating in gph, unless you drain the soap from the machine as an intermediate step (not real common).

[maple flats]

Very often especially early in the season before I have a lot of permeate stored, I just run a cold sap rinse, pushing sweet into the head tank for about 5 minutes, then I fill the wash tank with about 110-113F permeate. I then recirculate wash tank, thru high pressure pump, thru membranes and back to the wash tank. Initially the temp will drop because the membranes are full of cold sap or concentrate. Keep the pressure adjusted so both concentrate and permeate flows are about equal, as the membrane(s) become cleaner you will need to back the pressure off 2-3 or more times to maintain equal flows. Keep an eye also on the temperature, just pushing the flow thru the high pressure pump will cause the temperature to rise, shut it off when it gets to 113 or when 10 or even up to 20 minutes have passed. Then shut down, set up to send concentrate to drain and cold permeate to the permeate tank for 5 minutes. It's best to only do this method once, by the next time you run the RO you should have the necessary permeate to do a full soap wash routine. In the first method, the only permeate you used was 5 minutes pushing sweet to the head tank, and one wash tank full, then in the final cool down stage you lost just under half of the total flow (the concentrate part dumped) the rest is sent back to the permeate tank.

[pete3046]

Thank you, that was very helpful. I finished up my initial RO prep last night and hope for sap to process later next week!

[eustis22]

So I have been blessed with 2 new 400 gpd membranes and they have 1/2" npt fittings. I want to increase my throughput as 8-9 hours to process 70+ gallons is not optimal. My prior 150 gpd membranes connected with 1/4" tubing...with the bigger membranes (and new bigger pump) should I keep the 1/4" tubing or should I increase that to 3/8" tubing?

[maple flats]

That's hard to say,You can try it on the 1/4" but if that doesn't give you the flow you think you should get, 3/8 will about double the possible flow, that does not mean you will automatically double the flow. Too many variables, pump, length of tubing and the restrictions on the flow.

[eustis22]

I cannot find a needle valve to fit my 3/8 tubing. Will a push to connect valve work just as well to adjust pressure PSI?

[maple flats]

Not likely, try the 1/4" valve with the 3/8" tubing reduced back to 1/4 at that valve. If that gives you too much pressure you need to find a 3/8" needle valve. Try Graingers or other industrial suppliers.
Try this https://pipingnow.com/3-8-needle-valve-316-stainless-steel-6000-threaded-end-api-598-tci-tc-ndl/?msclkid=0fe969cf7bd9148a914e09f59753dbcc&utm_source=bing&utm_medium=cpc&utm_campaign=S%26O%20%7C%20Bing%20%7C%20Primary&utm_term=4585032211841661&utm_content=GSAPI%205ece7379d3936

[carls47807]

I have never seen a 400gpd membrane housing with 1/2" npt threads. Is 1/2" the ruler measurement, or are they actual 1/2" npt threads? I would run all your hoses 3/8" od, and terminate to a 1/4" concentrate hose on the last membrane, using a 1/4" needle valve. You can probably find a brass 3/8" compression style valve on amazon, but it probably won't be "zero lead" (which is different from "lead free", and much different from regular brass).

[eustis22]

Thank you, it's actually a 5/8" (by ruler) NPT and fortunately I have a 5/8 X 1/4" push to connect fitting I can hook the old needle valve line to. Will let you know how things work later today after I try my first wash.

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