Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

Nub here - First Post be nice - RO System Return

Options
Dannen
Dannen Member Posts: 4
I have an RO System serving mulitple feeders with a return loop. Pressure on supply is 45psig (press. setpoint control) The return has a PRV set @ 10 psig approximately 40 ft from feeder. The return also has a PRV set @ 5 psig at the return tank 100 feet downstream of the first PRV. Can someone tell me why these PRVs are required and what purpose they serve.

Comments

  • Jamie Hall
    Jamie Hall Member Posts: 23,286
    Options
    "PRV" can stand for two very different devices. A pressure reducing valve, or a pressure relief valve. There are also a couple of other valves which almost look the same -- pressure maintaining valves, and constant pressure drop valves.

    Could you perhaps be a little clearer on what we have? I can think of reasons why any of those four, at least, might be used in a reverse osmosis (RO) setting...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    Dannen
  • Mad Dog_2
    Mad Dog_2 Member Posts: 6,925
    Options
    Hiya Nub...Mad Dog 🐕 
    Dannen
  • Dannen
    Dannen Member Posts: 4
    Options
    PRV = pressure reducing valve in this application. Thanks for requesting the clarification, overlooked that possibility.
  • Jamie Hall
    Jamie Hall Member Posts: 23,286
    Options
    Hmm. Well, I'm afraid I need a diagram of the system at this point. At the moment, I can't really see why there would be a pressure reducing valve on the return, let alone two of them... they won't hold a constant back pressure. In fact, if the downstream pressure falls below the setpoint, they will open wide...

    Diagram, I think, if you can.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Dannen
    Dannen Member Posts: 4
    Options



    Hope this helps....

  • Jamie Hall
    Jamie Hall Member Posts: 23,286
    Options
    Doesn't enlarge well... the print is still blurry. But... if they are on the distribution lines (?) the first one may be to set an initial pressure for the four lines, and the ones on the lines may be to ensure that all four lines are operating at the same pressure -- and therefore at close to the same membrane throughput.

    That. Is a Wild **** Guess.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Dannen
    Dannen Member Posts: 4
    Options
    Meeting with the plumbing contractor today. Thanks for your feedback and yes its all about proportional balancing.
  • Sylvain
    Sylvain Member Posts: 121
    Options
    Are you sure the valves on the return are not some kind of balancing valves?

    see for example various models in this video (I have no affiliation with Caleffi):
    https://www.youtube.com/watch?v=PlbesL6PhfQ