RODI TDS control with GHL (or Apex)

[CEReefer]

Hi everyone, I just wanted to show some of my work here. This system can tell your controller if it can allow RODI production or not. My RODI system has 2 (for redundancy) motorized ball valves electronically controlled by my Profilux 4, when these are open RODI production starts.

I used:
- a PSC-64D from HM Digital, to measure TDS down to 0.0 ppm (the classic TDS meters go down only to 0), the device puts out a 4-20mA signal.

- then I used an Arduino Uno Rev3, with a 4-20mA signal receiver to decode the signal and set the trigger for one of the Arduino's digital outputs to a specific voltage (1.7V in my case) if the TDS goes above 1.

- The digital signal is then received by a PLM-ADIN card from GHL, if the voltage goes above 1, it won't allow my Profilux 4 controller to open the valves of my RODI filtration system.

If anyone needs help with any of this or the code to make this run, just hit me up.

 

[CEReefer]

Here are the US Solid motorized ball valves (red arrow). The yellow arrow indicates the 1/2" T fitting for the TDS prob of the PSC64-D controller.

 

[jtm235]

Very nice...I am working on a similar project using a Pi and Arduino Mega...to control a lot of stuff including ATO! Just a couple questions:

1) is that motorized ball valve metal? I think RODI water is corrosive to metal.

2) Also, Why not just use a 12v RODI solenoid? They are NC

3) Do you have any other fail safes other than redundant valves?

 

[CEReefer]

Very nice...I am working on a similar project using a Pi and Arduino Mega...to control a lot of stuff including ATO! Just a couple questions:

1) is that motorized ball valve metal? I think RODI water is corrosive to metal.

2) Also, Why not just use a 12v RODI solenoid? They are NC

3) Do you have any other fail safes other than redundant valves?

The motorized ball valves are controlled by my profilux and are stainless steel, they are positioned after the tap and before the filters so they aren’t in contact with RODI. I leave the tap open, and use them to replace the tap, I use 2 for redundancy. You want motorized ball valves as the heat from the solenoid could potentially “burn” the valve (or deteriorate it overtime) and tend to fail a lot.

I have a float valve in the RODI container as an additional redundancy, as well as an high level float sensor that shuts the valves off.

 

[KStatefan]

Not sure how I missed this when you first posted. This is cool.

I am wanting to clean up my setup to eliminate dual level controllers, delay relays mess i have now but it works.

 

[jtm235]

The motorized ball valves are controlled by my profilux and are stainless steel, they are positioned after the tap and before the filters so they aren’t in contact with RODI. I leave the tap open, and use them to replace the tap, I use 2 for redundancy. You want motorized ball valves as the heat from the solenoid could potentially “burn” the valve (or deteriorate it overtime) and tend to fail a lot.

I have a float valve in the RODI container as an additional redundancy, as well as an high level float sensor that shuts the valves off.

Nice, that's a good way to set it up. I am plumbing mine directly to the sump...Definitely with several safeguards in place such as:

- Float valve

- Mechanical water leak detector safety valve:


- Independent AC cutoff leak detector:


- And a digital leak detector built into the controller

This level sensor is used to trigger the ATO:

5 Etape Liquid Level Sensor With Plastic Casing

Multiple Function Sensor Development Tools 5 eTape Liquid Level Sensor with Plastic Casing

www.electromaker.io

Have you considered also running a separate RO flush cycle to mitigate TDS creep? I guess it's a problem depending on the run frequency of your RO/DI system.

 

[niccumec]

Here are the US Solid motorized ball valves (red arrow). The yellow arrow indicates the 1/2" T fitting for the TDS prob of the PSC64-D controller.

I like your use of motorized ball valve versus solenoids due to reliability….

I assume these ball valves cannot be NC (Normally Closed) in event of power failure, correct? Did you consider using one ball valve and one solenoid as your redundancy? Seems like that would add a NC capability to the system.

Which model did you use? 1/2” or 1/4” and how you adapt to the 1/4” RO tubing?

 

[niccumec]

I like your use of motorized ball valve versus solenoids due to reliability….

I assume these ball valves cannot be NC (Normally Closed) in event of power failure, correct? Did you consider using one ball valve and one solenoid as your redundancy? Seems like that would add a NC capability to the system.

Which model did you use? 1/2” or 1/4” and how you adapt to the 1/4” RO tubing?

Ahh, I now see the 1/2” version has NC. Solid 1/2”

 

[n2585722]

I like your use of motorized ball valve versus solenoids due to reliability….

I assume these ball valves cannot be NC (Normally Closed) in event of power failure, correct? Did you consider using one ball valve and one solenoid as your redundancy? Seems like that would add a NC capability to the system.

Which model did you use? 1/2” or 1/4” and how you adapt to the 1/4” RO tubing?

I have been using solenoids for doing this for years now and I have not had any issues but they are normally left off unless the RODI unit is in use. I have one on the input to the RODI unit and two on the output. One is used to refill my DI reservoir and the other to refill my mix tank. I also have one for a flush valve. The 4 solenoids for the RODI are in the top of this photo. The RODI unit is in my garage.

 

[niccumec]

I have been using solenoids for doing this for years now and I have not had any issues but they are normally left off unless the RODI unit is in use. I have one on the input to the RODI unit and two on the output. One is used to refill my DI reservoir and the other to refill my mix tank. I also have one for a flush valve. The 4 solenoids for the RODI are in the top of this photo. The RODI unit is in my garage.

Good to hear on your Solenoid reliability. I have seen lots of posts of failures, which also surprised me as they should only need to be energized while RO is in operation. Perhaps those people have constant start stops due to using a float instead of allowing the RO reservoir to deplete and make larger batches. Larger batches seem better for TDS creep and for not cycling the solenoid as much.

Can’t read the brands you use in the picture. Any preference on solenoid brand / specs?

 

[n2585722]

Good to hear on your Solenoid reliability. I have seen lots of posts of failures, which also surprised me as they should only need to be energized while RO is in operation. Perhaps those people have constant start stops due to using a float instead of allowing the RO reservoir to deplete and make larger batches. Larger batches seem better for TDS creep and for not cycling the solenoid as much.

Can’t read the brands you use in the picture. Any preference on solenoid brand / specs?

Three of my solenoids are U.S. Solid brand. Two are Hydros brand solenoids. The Hydros are the newer ones but are around 3 years now. I got them to try them out and used them on the DI output. One is for DI reservoir refill and the other for mix tank refill. One is not in the photo it is in the RODI unit for a flush valve. I also have one on the DI output that goes to drain if I need to flush that line for any reason like when the DI resin and filters are changed. All are 12v DC solenoids controlled from 12v outputs on my controller.