hodorskib's Small Scale RO Build

[deitzd]

Did some testing with well water this morning. At zero pressure there is some flow from the permeate line, about 10% so it's not plumbed backwards. With clear tubing at the bottom of each housing I could see flow (and bubbles) from the permeate side of all 5 of the housings. I also tested each individual housing and get a little bit of flow from the permeate side at zero pressure. With the whole system together the most I can get is 68 pounds of pressure on the gauge between the 5 micron filter and the first housing. This is with the screw on the pump head at max.

This system is in my basement and has never been subject to freezing temps so I don't suspect a cracked housing, although anything is possible. I'll replace all the o-rings this afternoon and give it another try.

Thanks for the great advice.

[Msboucha]

This system is in my basement and has never been subject to freezing temps so I don't suspect a cracked housing, although anything is possible.

Crack wise, I was thinking more of a manufacturing defect. After patching the first housing I had that sprung a leak, I ordered a spare in case it didn't hold. When the next one blew a pinhole in the same spot, I went to throw in the spare only to find it had the pinhole defect brand new out of the package. They are pretty cheap, so it really wouldn't surprise me.

[deitzd]

Crack wise, I was thinking more of a manufacturing defect. After patching the first housing I had that sprung a leak, I ordered a spare in case it didn't hold. When the next one blew a pinhole in the same spot, I went to throw in the spare only to find it had the pinhole defect brand new out of the package. They are pretty cheap, so it really wouldn't surprise me.

Would this defect be visible inside the housing?

[Msboucha]

Maybe, I was only able to identify the exact pinhole location the first time because it was misting under 150psi. It was right in the center of bottom of the housing where it comes off the form machine. It almost wasn't visible otherwise.

[hodorskib]

Don't worry about pressure when you are running water - most likely well under 100psi more likely around 60psi. You should also leave the needle valve wide open when flushing so there will be little to no pressure. As for sugar in your permeate. My refractometer has some issues with % under .5 do yourself a favor and take a quart to a half gallon of permeate and boil down to 25% let cool and then take a reading. If it is reading the same as your initial number you are not passing any sugar. Good luck.

[deitzd]

Well, I replaced all 10 of the o-rings and it seems to have made a little difference but not much. I'm still getting liquid from the permeate line at zero pressure. I checked each individual housing and I still get fast drips of liquid from the permeate side of all 5.

I loaded the system with sap and I can easily attain 100 psi between the 5 micron filter and the first housing (I didn't check this prior to changing the o-rings). I'm getting almost exactly 50/50 from each line at 90 lbs of pressure. I measured the concentrate at 5.2 Brix with the refractometer. The permeate is at 2.1 Brix.

I boiled 1/2 gallon of the permeate down to 16 ounces. By the time I was half done I could tell by sight and scent that there's plenty of sugar in it. I let it cool to a little over room temp and it measured at 8.6 Brix.
IMG_9855.jpg

I definitely have a problem here. What are my next steps? I did find a place where I can get 5 new housings for $47.42 shipped.

[deitzd]

BTW: I did lube the o-rings and the top gasket with a water based lube when reassembling.

[Msboucha]

How is the rubber seal around outer top of the membrane itself - you said something like they had wrapped them in plastic and shoved them in the housings? Is it maybe deformed a bit and letting sap by?

[deitzd]

Yeah, when they shipped them they put the membranes (which were wrapped in their plastic packaging) inside of the housing for shipping.

That rubber seal seems okay. I rubbed my fingers around them when I lubed them for reassembly and didn't notice any rough or flat spots.

I ordered 5 new housings. I hope that does it because the only thing to replace after that are the membranes.

Just a little more information: I ordered all of the supplies for this project last May so the membranes were stored that way for quite a while. I'd consider contacting the supplier but it was so long ago.

[Msboucha]

Grasping at straws here -- how did you do your initial flush? Pure water or sap? I read somewhere else on the forum that it was advised to use only water as using sap could cause the membranes to foul before they are even put to work. Elsewhere I've read that fouled membranes can pass sugar and need an acid wash to reset the pores in the membrane. Seems far fetched for what you have setup though.