Establishing RO baseline

[mol1jb]

I am trying to understand my RO baseline and when to wash due to lower flow rates. Ray said to establish the baseline by setting the pressure at 150psi after a rinse and recording both conc and perm flows. He said to do it after the second use to have an accurate baseline. I took the first reading after the first use after rinse was at 150psi and conc and permeat reading both 1.5gph. After the second use flow after rinse was 1.6 conc and 1.4 perm. So I am taking as my baseline. Then after rinse yesterday my conc was 1.8 and perm 1.2.

So my question is how low of flow would warrent a wash to get my flow rates closer to my baseline? And is my method of establishing the baseline sound?

[JoeJ]

I have a Lapierre 1200 RO. I think that you need to have a flow temperature in your baseline. I know that I have a different machine but the instructions I use for my base baseline are: 1. permeate flow 3 gpm, 2. pressure set at 150 PSI, 3. run machine until the water temperature is 75 degrees and then take concentrate flow reading.

I do a baseline check after every wash. If your readings drop 15% below your initial baseline, it is suggested you do an citric acid wash.

Joe

[bmbmkr]

https://www.mapleexperts.com/membranes

I bought a used Deer Run 125 and used it last year. This year I upgraded it to electric, added another vessel and two brad new XLE's this year. I used MES info to benchmark it, and as Joe said, temp does make a huge difference. I run it at 150-225, and keep an eye on the gauge, once it starts to climb, I back of a little and/or adjust the recirculation. The NF270 membrane does a good job, but I found I had to do 2 passes, my evaporator only run 20 gph so I had no problem keeping up. I am running 2 passes this year too, I run a cold permeate flush about every 2 hours, and hot permeate at the end of the day. I'm using a 150 quart cooler for wash tank, I have male Cam lock screwed on the water hose fitting on the cooler drain, works really well keeping the wash water warm. With 2 membranes and a 330 PC pump, it outgrew the little wash tank that came on it. Once you run it a few times and pay attention to the gauge you will figure out what she's doin. I really enjoy all the time and wood I'm saving.

[mol1jb]

I appreciate the info. I didnt think about temperature but that makes sense. I will have to get a thermometer into the intake line to monitor temp to keep readings consistent.

[bowhunter]

All major membrane manufacturers rate the membrane capacity on water at 77F. For each degree below 77 you lose about 3% of the permeate capacity at a given pressure. For example at 77F the permeate flow factor is 1.0. At 60F it's 1.40, at 50 F it's 1.71 and at 40 F it's 2.30. So if you test you membrane at 50F you would multiply the permeate flow you measure by 1.71 to adjust it to 77F. Most manufacturers also can provide a table for adjusting the permeate rate at different temperatures.

All membrane are generally rated at 50, 70 or 100 psi. I believe MES uses 125 psi. When your membrane is new or has just been cleaned pick a pressure to use every time and measure the temperature. Record the permeate flow while running the system on permeate and use the temperature adjustment to calculate the permeate flow at the baseline temperature of 77 F.

If you have to do a permeate rinse during a run then you probably are running the recovery too high. That can be a problem with a machine set up for once through. It probably won't cause any permanent damage but it's a nuisance to stop and rinse. Most membrane manufacturers recommend a maximum of 15% recovery per pass for good consistent operation. Recovery is the % of the flow through the membrane that is removed as permeate. I have a small membrane similar to the NF 270. I rinse it with permeate at the end of each day. I've never had to rinse it mid run and I only have to do a soap wash at the end of the season. I think I've done one soap wash mid-season in 4 years. I always run the recovery at or below 15% but the system is set up to run permeate recirculation to keep the recovery low.

[mol1jb]

Good information. So I need to start with the membrane specs. I believe Ray uses the NF270 in his RO's. If I am wrong someone tell me.