Float valve for RODI Waste Water Container?

[chowberg]

I'm currently setting up a Salt Water Mixing station. I'm planning on collecting the waste water in another barrel to water my plants. Since my RODI unit creates a 1:2 gallon ratio, I wanted to put a float valve on the waste container so it doesn't over flow. Would this stop the production of filtered water or will it reroute my waste water into my RODI filtered barrel?

I have the BRS 5 stage with flush and auto shut off kit. I also plan on installing a float switch on the RODI filtered water barrel as well.

 

[Sisterlimonpot]

using just a float valve may not be the best choice because you can run the risk of fouling the membrane. If the water isn't being rejected it has to go somewhere and the only place it can go is to through the membrane, which it physically wont allow and thus starts the process of clogging the membrane.

What you would want to do is to stop the tap water going into the RODI. A simple way to do this is place a float switch inside the waste water barrel and once it's full it will open the circuit that turns you RODI on and off, that's assuming that you unit is automated.

If it's not then it has to be done mechanically by having a float valve inside the waste water barrel but you'll have to re-purpose the traditional auto shutoff like this one. That piece that has 4 connections has two halves separated by a piston/diaphragm, which in your case keeps the waste water on one side and the incoming tap water on the other. As long as the pressure on the waste water side is less than roughly 2/3 the pressure on the tap water side, the piston/diaphragm remains open and the unit continues to produce water. As the RODI produces water and slowly fills the waste water tank, the float valve will close and create enough pressure to force the piston toward the tap water side and shut off the incoming tap water, stopping production. That's why a float value is needed to increase the pressure, otherwise you will overfill the container. The RODI unit stays off until enough water is removed from the waste water tank to drop the float-valve/pressure on the tank side of the piston, allowing tap water pressure to push the piston/diaphragm toward the waste water side and start RODI production again.

 

[chowberg]

Hi Jimmy - thanks for the very thorough response.

I do not have an automated system, so I'll need to go the mechanical route.

I have the BRS RODI system that came with an Auto Shut Off unit - I assume I can re-purpose that one, correct? I'm confirming that I do not (and should not) run two Auto Shut Off units, correct?

Thanks again!

using just a float valve may not be the best choice because you can run the risk of fouling the membrane. If the water isn't being rejected it has to go somewhere and the only place it can go is to through the membrane, which it physically wont allow and thus starts the process of clogging the membrane.

What you would want to do is to stop the tap water going into the RODI. A simple way to do this is place a float switch inside the waste water barrel and once it's full it will open the circuit that turns you RODI on and off, that's assuming that you unit is automated.

If it's not then it has to be done mechanically by having a float valve inside the waste water barrel but you'll have to re-purpose the traditional auto shutoff like this one. That piece that has 4 connections has two halves separated by a piston/diaphragm, which in your case keeps the waste water on one side and the incoming tap water on the other. As long as the pressure on the waste water side is less than roughly 2/3 the pressure on the tap water side, the piston/diaphragm remains open and the unit continues to produce water. As the RODI produces water and slowly fills the waste water tank, the float valve will close and create enough pressure to force the piston toward the tap water side and shut off the incoming tap water, stopping production. That's why a float value is needed to increase the pressure, otherwise you will overfill the container. The RODI unit stays off until enough water is removed from the waste water tank to drop the float-valve/pressure on the tank side of the piston, allowing tap water pressure to push the piston/diaphragm toward the waste water side and start RODI production again.

 

[Sisterlimonpot]

I don't see the harm in having 2 of those piston/diaphragm. But to be honest, you can simply re-use the one you have. I have a BRS as well, I snapped a few photos of the piston/diaphragm. they're not good pics because it's a tight fit to snap pics but you'll get the idea.

I got the unit used so I can't attest to the tube colors being the same as yours, but the red tube leaves the right side of the 3 prefilters and enters the right side of the piston/diaphragm then it exits the left side and runs to the membrane housing on the left. The blue line runs from the right side of the membrane through the diaphragm then over to the DI containers.

In this case, I would remove the blue lines and reconnect them with one of those John Guest fittings and cut the drain line at a convenient location so that you can connect it through the diaphragm.

After that I would test the unit to be sure it works properly. Lower the waste water float valve and allow the system to run for a few minutes then close off the float valve and ensure that water stops flowing out of the 0 TDS tube. If all goes right, it will shut off tap water at the piston/diaphragm.

Keep in mind that if you're also using a float valve on the 0 TDS line that you no longer have the capability to shut off the inlet water like it was previously. if you want to do that then you will have to purchase another piston/diaphragm and run it in line of the (in my case) the red tube.

I hope that these instructions are clear enough to follow. and I hope that it goes as planned. Please let me know your results.

 

[Smokey Stover]

How large a barrel for waste water? Could you just run it outside? Or do you mean indoor plants?

 

[Lyscer]

Maybe I'm not catching the full vision here. An idea would be to patch a bucket inline with the waste water line. Put both lines at the top of the bucket on the sides so that as the water fills it up it can just drain out the other side and down the drain or wherever you have it. Then you won't have to worry about back pressure on the waste line resulting in poor membrane production and fouling of the membrane. If you use John guest fittings you can easily pop the lines on and off.

 

[chowberg]

This was actually my initial idea, but I wanted to have the waste water prevent any additional fill up the RODI filtered because I do have plenty of use for the waste water (filling up the pool, water plants, etc.). However, this may be my back up plan as it might be an easier set up. Thanks for your input!

Maybe I'm not catching the full vision here. An idea would be to patch a bucket inline with the waste water line. Put both lines at the top of the bucket on the sides so that as the water fills it up it can just drain out the other side and down the drain or wherever you have it. Then you won't have to worry about back pressure on the waste line resulting in poor membrane production and fouling of the membrane. If you use John guest fittings you can easily pop the lines on and off.

Wow - thanks for taking the pictures for me, the instructions are clear and I think I have all the info I need. Thanks again!

I don't see the harm in having 2 of those piston/diaphragm. But to be honest, you can simply re-use the one you have. I have a BRS as well, I snapped a few photos of the piston/diaphragm. they're not good pics because it's a tight fit to snap pics but you'll get the idea.

I got the unit used so I can't attest to the tube colors being the same as yours, but the red tube leaves the right side of the 3 prefilters and enters the right side of the piston/diaphragm then it exits the left side and runs to the membrane housing on the left. The blue line runs from the right side of the membrane through the diaphragm then over to the DI containers.

In this case, I would remove the blue lines and reconnect them with one of those John Guest fittings and cut the drain line at a convenient location so that you can connect it through the diaphragm.

After that I would test the unit to be sure it works properly. Lower the waste water float valve and allow the system to run for a few minutes then close off the float valve and ensure that water stops flowing out of the 0 TDS tube. If all goes right, it will shut off tap water at the piston/diaphragm.

Keep in mind that if you're also using a float valve on the 0 TDS line that you no longer have the capability to shut off the inlet water like it was previously. if you want to do that then you will have to purchase another piston/diaphragm and run it in line of the (in my case) the red tube.

I hope that these instructions are clear enough to follow. and I hope that it goes as planned. Please let me know your results.

I have a 60ish gallon barrel in my garage for waste. Unfortunately I don't have an easy way to run it outside.

How large a barrel for waste water? Could you just run it outside? Or do you mean indoor plants?