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Capillary Flow Restrictor Placement


Fnard

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Ok folks, totally noob/jackass question, but here we go. Have had ro/di unit for several years. Finally got around to noticing that there was no flow restrictor on unit (got on ebay). So ordered myself a restrictor that matched my unit. Now the question is, where does it go? Which way does it go in? Tail upflow or downflow? Doesn't seem like the end of the waste line is a good idea as it may eject itself out. Any help would be nice as I don't really want to be wasting all that water now that I am paying for it. Someone wake up AZDesertRat.

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You had to have a flow restrictor to get any RO water, without a restrictor everything goes out the waste line. The restrictor causes the back pressure that drives the treated water through the membrane.

The restrictor can be a small white cartridge looking piece in the waste line, usually with printing on it like 500mL or 750mL or similar on it, a 90 degree elbow off the RO housing which if you remove it and look inside, a tee with a valve in the waste line commonly called a flush kit or a small piece of tubing inside the waste line right off the RO housing that looks like a piece of spaghetti with a flange on one end, a capillary tube. If you made any RO water at all you have one of these.

To answer your question though, the capillary tube is inserted in the waste line directly off the RO housing, usually after the 90 degree elbow with the flange nearest the elbow. You will need to check the waste and trim the length of the tube to suit your conditions.

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You had to have a flow restrictor to get any RO water, without a restrictor everything goes out the waste line. The restrictor causes the back pressure that drives the treated water through the membrane.

The restrictor can be a small white cartridge looking piece in the waste line, usually with printing on it like 500mL or 750mL or similar on it, a 90 degree elbow off the RO housing which if you remove it and look inside, a tee with a valve in the waste line commonly called a flush kit or a small piece of tubing inside the waste line right off the RO housing that looks like a piece of spaghetti with a flange on one end, a capillary tube. If you made any RO water at all you have one of these.

To answer your question though, the capillary tube is inserted in the waste line directly off the RO housing, usually after the 90 degree elbow with the flange nearest the elbow. You will need to check the waste and trim the length of the tube to suit your conditions.

 

Ummm, OK. I trust you, but I've definitely been making RO and RODI somehow without it. I have a T before leading into the DI chamber with a valve so that I can get straight RO water. In the pict, the red arrow points to the valve for just RO and the blue arrow is where I have placed the flow restrictor.

 

IMG_20160108_214817.jpg

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Need better pictures but I absolutely guarantee you, if you are getting RO water you have something restricting the waste flow. If you didn't everything would go out the waste line. Do I also see something metal on the treated water side?

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Will try and get a better picture. The metal you see is prolly the hookup. Its a washer valve. I capped off the hot water feed and the RODI unit is hooked up to the cold feed.

 

As far as the RO water, would anything come out w/o restrictor? I'm assuming this only pertains to RO and not RODI?

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More picts. Hopefully they help

 

Full SetupIMG_20160108_221941.jpg

 

T off of DI cartridge. Feed from RO is rear tube, front tube to spigot (closed RODI, open RO), threaded part into DI canisterIMG_20160108_222028.jpg

 

Spigot off of T from DI

IMG_20160108_222034.jpg

 

Flush kit off of RO membrane. (yes, i know how you feel about them. never use it anyways.

IMG_20160108_221954.jpg

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An RO membrane is so fine or small only pure water ions pass through so it takes the flow restrictor to create the back pressure to make it work. Without a restrictor you get no treated water, it takes the path of least resistance out the waste line. If you get any RO or RO/DI water you have some form of restriction. It either goes out a 1/4" unrestricted opening or through a semipermeable RO membrane rated at 0.0001 microns, that is 40,000 times smaller than you can see with your eyes. Which path do you think it is going to take?

An RO membrane is so fine or small only pure water ions pass through so it takes the flow restrictor to create the back pressure to make it work. Without a restrictor you get no treated water, it takes the path of least resistance out the waste line. If you get any RO or RO/DI water you have some form of restriction. It either goes out a 1/4" unrestricted opening or through a semipermeable RO membrane rated at 0.0001 microns, that is 40,000 times smaller than you can see with your eyes. Which path do you think it is going to take?

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OK, now I see your flow restrictor.

On your waste line you have what is commonly called a "flush kit". It's worthless but that is beside the point. The kit has a straight through line and a line with a ball valve on it. Inside that straight line is a capillary tube flow restrictor. The ball valve is a bypass around the restrictor that in theory flushes the membrane when you open it but in reality gives you a warm fuzzy feeling and does little. You do have a restrictor so remove the complete flush kit and use the new one after you check and adjust it or remove the new one and leave it as is or at least check your waste ratio to see that it is the correct 3:1 to 4:1.

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OK, now I see your flow restrictor.

On your waste line you have what is commonly called a "flush kit". It's worthless but that is beside the point. The kit has a straight through line and a line with a ball valve on it. Inside that straight line is a capillary tube flow restrictor. The ball valve is a bypass around the restrictor that in theory flushes the membrane when you open it but in reality gives you a warm fuzzy feeling and does little. You do have a restrictor so remove the complete flush kit and use the new one after you check and adjust it or remove the new one and leave it as is or at least check your waste ratio to see that it is the correct 3:1 to 4:1.

Unfortunately, there is no restrictor in that bypass. Only reason I know, is because I'm the one that had bought it awhile ago and put it on. Now this is getting frustrating. I know you know what you are talking about, but at the same time, I am absolutely sure there has been no restrictor on this unit. But yet I have been able to yield RODI water for the past 5 years min.

Oh, and the pressure in the unit is still the same as w/o restrictor. Usually between 70 to 80

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Did you remove the straight tube from the flush kit and look through it?

If you have 70-80 psi on your gauge and it is not stuck, something is restricting flow. I know you doubt my word but you do have something somewhere and if you were close to Phoenix I would disassemble the system and show you. Water isn't going to pass through a 0.0001 micron membrane when it has a 1/4" unrestricted opening to waste.

 

The only other option is the membrane is ruptured or compromised and water is bypassing it without being treated. What is your tap TDS, RO only TDS and RO/DI TDS? What is your exact measured waste ratio? Have you measured your flow to see what you actual gpd is? It is easy to calculate what to expect if you know the water pressure and temperature as well as how much you are wasting.

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I know you doubt my word but you do have something somewhere and if you were close to Phoenix I would disassemble the system and show you.

No no. I'm sorry if I'm giving you that impression. I trust and understand what you are saying. That's what is so perplexing. Hopefully tomorrow, but Sunday is more likely, I will test the tds readings again and rejection rate. Both with and without the new restrictor I put in. Also will tear out all the tubing and look for anything I missed. If you have any other suggestions/tests I should run lmk. Thanks for the help.

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Trust me, if water is going through the membrane, something is making it do so. It's not going to pass through an opening 40,000 times smaller than you can see if it has an open 1/4" tube to flow out of, doesn't work that way.

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