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Need HELP w/Developing Elec. Schematic and Ctrl Ops for Reverse Osmosis System

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  • Need HELP w/Developing Elec. Schematic and Ctrl Ops for Reverse Osmosis System

    Hello! I'm building a homemade mobile reverse osmosis system for maple sap. I've plumbed and built the mechanics of the system, but am at an impasse as how to wire the machine with several control functions. I'm in over my head, as I knew I would be. Hoping to get some help on design and recommended components for this set up.

    I know I'll need the following functions:
    PWR Switch (220/240) - light indicator for power
    Push Start starts low pressure feed pump. Once low pressure reaches 30 psi, then high pressure pump turns on (light indicator?); if high pressure psi is exceeded, shut ALL down (light indicator?)
    If temp exceeds 110F, shut ALL down (light indicator?)
    If pressure drops below 30 psi, shut ALL down (light indicator?)

    I've attached the Reverse Osmosis (RO) mechanical sequence, pictures of the machine, and a list of components I have on hand. Thanks in advance.
    Attached Files

  • #2
    So, are you asking to have us to recommend Automation Direct components to complete your work? I'm currently working on a level sensing project and found the Click PLC C0-02DR-D and C-more micro HMI EA3-S3ML-RN to be the most affordable solution. You'll need pressure sensors, and a temp sensor. Your pushbuttons and pressure readouts and lights could be programmed in the C-more.
    Why worry? If you've done the best you can, worrying won't make it any better

    - Walt Disney


    • #3
      Here is a post on the five steps to program development. You may find this helpful.

      The BRX PLC is also a good choice because you can simulate your project without hardware.
      The C-More or C-More Micro is good for your HMI. (Human Machine Interface)

      Here is a good beginner guide to PLC's that you might find helpful.
      You can skip the sections that may not apply.



      • #4
        Seems to me a PLC would be overkill, just conventional relays and switches should do fine.
        I see a note on your components list; "concerned this controller cannot handle 240V", but there is also in the specs. for the contactors; "120 V coil", however I don't see a control transformer on the list? Personally I wouldn't use 240VAC for a control circuit, I prefer 24VDC, but 120VAC via transformer is ok too I guess.
        You might need to double check on motor overload protection, while built in thermal protection is fairly common on single phase moters it is not universal and I don't see it shown for your high pressure pump motor. Also with external protection, if one motor does trip its protection you'd be able use an auxiliary contact to shut down the entire system.

        Do to liability issues I wouldn't want to design it for some one else, but it seems simple enough.


        • #5
          Thank you Todd Dice, Garry and Tinker for your responses and information provided. I am seeking help with components and set up as this is out of my wheelhouse. The PLC may be more advanced than I need. I thought that the conventional relays and switches, as Tinker mentioned, would be sufficient. I have several Packard contactors, but get lost about the auxiliary contacts N.O., N.C., etc.

          In conversation with others, I was contemplating incorporating an external protection for thermal overload using an auxiliary contact to shut down the whole system.

          Todd Dice I have pressure and thermal switches/sensors. (GEMS pressure sensors, Inkbird ITC-1000 for temp controller).