RO system issues

[Buckeye_Hydro]

We're referring to the walls of the "cup" into which the membrane seats. Sometimes these will crack.

Russ

 

[Blackdirt_cowboy]

It's a brand new membrane housing. I'll check the volume ratio and report back.

 

[Blackdirt_cowboy]

So I got back home and did a check on my ratio of permeate to waste water. I turned off the pressure tank and disconnected the waste water line from the drain and took the permeate line loose coming out of the post carbon block. I let the system run for 45 seconds. I ended up with 10 oz of waste water and 13 oz of permeate. The permeate tested 572 TDS and the waste water tested 705 TDS.

I am assuming that I have mixing of the waste water and the permeate in the membrane housing. I am not an expert on these systems at all, but I would think I should have more waste water than permeate. Is it possible that I still don't have the membrane seated correctly? When I put it in the housing, I can feel when the o-rings "catch." Then it snaps into place. If tried taking pliers and pushing it in further, but it won't move anymore. It then takes a pair of pliers to pull the membrane back out. Keep in mind that this is a brand new membrane and membrane housing.

Edit: I just rechecked the membrane. It is seated properly and there is no damage to the o-rings. I can't believe that a brand new membrane housing is cracked, as its rare to have an old one cracked. Also, this problem is happening on both of my RO systems that are plumbed identical. That's telling me something is going on in the plumbing part of them. The only thing we haven't checked is the auto shut off valve. Could it somehow be contributing to this problem?

 

[Buckeye_Hydro]

Sounds like a membrane not fully seated or an internal crack in the housing. Yes - you have "too much" permeate.

Are your carbon prefilters ancient and allowing chlorine through?

2 systems doing the same thing? Wish I had them in front of me. Has to be something pretty obvious.

 

[Blackdirt_cowboy]

I'm on well water, no chlorine at all. I took the membrane out again. I put it back in and when it felt like it seated, I put the intake end of the membrane and put it against the rounded corner of my countertop. I then pushed against it with all the force I could muster, and it wouldn't move a bit. So the membrane is fully seated. I've got the whole thing taken apart now. I can't see anything wrong anywhere. One question I have, is that in the elbow that discharges the permeate, there is a little restrictor in there. Is that supposed to be there?

Also, with the membrane housing completely disconnected, I plugged the permeate discharge and left the membrane in the housing. I took off the cap on the housing to expose the end of the membrane. I then applied air pressure to the waste water discharge port. I was able to blow air back by the big rubber ring that encircles the entire membrane towards the intake end. Is that normal?

Edit: I removed the o-rings from the membrane, just to see how far the membrane went in with no resistance. It's going in the same distance as it does with the o-rings, so I'm definitely getting the membrane seated correctly.

 

[Buckeye_Hydro]

One question I have, is that in the elbow that discharges the permeate, there is a little restrictor in there. Is that supposed to be there?

You should not have a flow restrictor there (those go on the concentrate line, but would be perfectly normal to have a CHECK VALVE inside the elbow.

I then applied air pressure to the waste water discharge port. I was able to blow air back by the big rubber ring that encircles the entire membrane towards the intake end. Is that normal?

Yes... but don't do that! Never want any backwards flow through the membrane. In your case hopefully the air just went around the membrane and brine seal.

I removed the o-rings from the membrane, just to see how far the membrane went in with no resistance. It's going in the same distance as it does with the o-rings, so I'm definitely getting the membrane seated correctly.

Seating the membrane is quick and easy - paying as much attention to that as you have I have no doubt it is seated.

 

[Buckeye_Hydro]

by chance do you mistakenly have two flow restrictors installed?

 

[Blackdirt_cowboy]

No sir. But I did just figure out what my problem is. I either have a bad auto shut off valve or it's plumbed wrong. I took the auto shut off valve and pressure tank out of the system. So I have it plumbed like this:

Feed water--->sediment filter--->carbon filter--->RO membrane.

I don't have the taste/odor eliminator hooked up. My feed water TDS is 600. TDS coming out of the carbon filter is still 600. The permeate TDS is now 42. That gives me a rejection rate of 93%. Please let me know when I can call you to tell you what I did, so maybe you can tell me if I am plumbed wrong or if I need new auto shut off valves.

 

[Buckeye_Hydro]

You can call now: 513-312-2343

PM me your email, and I'll send you a set of instructions, including a diagram, to hook it up correctly.

Russ

 

[ajdelange]

... this problem is happening on both of my RO systems that are plumbed identical. That's telling me something is going on in the plumbing part of them.

Roger that.

 

[leesmith]

Any update?

 

[Blackdirt_cowboy]

Yes. I think the mystery is solved. I just finished installing new autoshutoff valves and check valves. Everything appears to be working correctly. I'm showing a 90% rejection rate based off the TDS reading. I know that seems a little low, but I feel like it's still flushing out system from it not working for so long. I really appreciate everyone's help on solving this issue, especially Russ at Buckeye Hydro. It took many phone calls to him to get this thing going.

Now that I know the rejection rate is 90% based off the TDS, can I extrapolate that to the calcium, magnesium, etc. that was in my prior water test results? For example, in my last test, sodium was 226 ppm. Can I assume that my sodium level is now 22.6 (10% of 226)? I want to brew this weekend, but don't have time to resemble and get the results.

Once again, thank y'all for all the help.

 

[leesmith]

Just treat it like distilled water and adjust from there.
The amount of ions left over is minimal.
Glad it worked out!

 

[Buckeye_Hydro]

http://msdssearch.dow.com/Published...seps/pdfs/noreg/609-00240.pdf&fromPage=GetDoc

But I think Leesmith's advice is how most brewers approach the situation.

Russ