Acid wash

[wiam]

I can find very little about how to do an acid wash. I bought a jar of Leader citric acid that says to use 2/3 cup to 2/3 wash tank of water. I have a home built 15 gallon wash tank on my old Memtek. Not sure how big Leader's tank is? What pH should I go to? Does it work better if heated? How do you decide when to? I have heard that a lot don't.

[bowhunter]

William,

Here's some info from Dow that should help you. Part of the answer depends on what membrane you have. If you keep the wash temperature around 95 F you can use 1-2 pH for most membranes. If you have one of the high flow nanofiltration membranes such as a NF 270 you need to stay a little milder...say no lower than pH 2. A 1.0 wt% solution of citric should have a pH of 2.0-2.2. To 10 gallons of water add 13 ounces of citric acid. Start with that mixture and check the pH. Add small amounts of citric acid to get it down to 1-2 pH if needed.
http://msdssearch.dow.com/PublishedLiteratureDOWCOM/dh_004f/0901b8038004f07d.pdf?filepath=liquidseps/pdfs/noreg/609-02089.pdf&fromPage=GetDoc
http://msdssearch.dow.com/PublishedLiteratureDOWCOM/dh_004f/0901b8038004f0c1.pdf?filepath=liquidseps/pdfs/noreg/609-02091.pdf&fromPage=GetDoc
http://www.atlanticro.com/3.CleaningSolutions.pdf

[briansickler]

I can find very little about how to do an acid wash. I bought a jar of Leader citric acid that says to use 2/3 cup to 2/3 wash tank of water. I have a home built 15 gallon wash tank on my old Memtek. Not sure how big Leader's tank is? What pH should I go to? Does it work better if heated? How do you decide when to? I have heard that a lot don't.

I have an old Osmonics RO. It has two copper tubing lines with compression fittings. Had no leaks until I did the acid wash. Now I have two dripping compression fittings. I tried to tighten them, but still leak. I plan to replace the two copper lines with stainless. You should be ok if you have all stainless plumbing on the RO.

[wiam]

I have an old Osmonics RO. It has two copper tubing lines with compression fittings. Had no leaks until I did the acid wash. Now I have two dripping compression fittings. I tried to tighten them, but still leak. I plan to replace the two copper lines with stainless. You should be ok if you have all stainless plumbing on the RO.

No stainless. Most plumbing is copper. This could get interesting. :/

[bowhunter]

Copper isn't ideal for low pH applications, but it should last for a while. In fact copper is better than mild stainless steel at the concentrations we're talking about.