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Right, it's controlled by flow, but the only reason it exists is to create backpressure to assist loop consumers.

My understanding and interpretation of how it works is as follows: The backpressure valve closes as flow rate increases above 170 GPM, eventually shutting off completely to prevent starving consumers. When the flow rate is at or under 170 GPM, the backpressure valve is wide open. The VFD...

a) Noted. I'm going to try and make that automatic. b) Noted. c) That makes sense, I didn't even think about that. I'm going with an electrically actuated v-ball with position feedback because that's my area of comfort. I'm sure the pneumatic stuff would work great, I just don't want to run air...

I went ahead and re-drew the diagram to make sure I understood it and to incorporate errata, as well as adding the dual pump setup. Hopefully this seems correct:

I'm going with George's design because it makes complete sense. It's similar to what I started with but with all the missing blanks filled in. I thank you very much for your help and drawing. To limit tank fill rate I had been relying on pipe sizing, but using a CDX device on those is a good...

Interestingly enough, in the US it's kind of the opposite. Although we obviously do try to make a good product to high standards, there is essentially zero regulation on cosmetic products as long as we make no claims on the label, which I'm sure is quite different to most of the rest of the...

We remove the city water chlorination to prevent R.O. membrane damage on the advice of the R.O. manufacturer Suez, a.k.a. Veolia after a rebranding recently. But it looks like there may be other pretreatment options that won't damage the membranes, so I will approach them to discover what...

Thanks for your input and for the interesting links. We are currently taking city water through carbon pretreatment to remove chlorine/chloramines and then through water softeners before going to the R.O. units, and did have some fouling after several years. So I wonder how much of a difference...

I've reached out to see if I can get a power curve, although I don't have much hope for getting one from this manufacturer (AMT). Regarding the UV reactor, it has 4 inch in/out flanges and a 6 inch body, so a massive amount of flow *could* go though it, but then you lose all your dwell time to...

Thanks, that makes sense and I was thinking about it a bit backwards. I'm definitely going to start with George's diagram and use it to update my initial design. I appreciate you guys for letting me bounce ideas off the wall because I'm still working to understand and grok the how and why of the...

OK, so I'm thinking about the suggestion to put the regulating valve in front of the filters at the end of the loop. As the filters load up, this will increase the backpressure on the valve. With a pilot operated valve, my assumption is that I would sense flow downstream of the filters in order...

Thank you for this diagram and suggested implementation. I'm not familiar with the PIC and FIC terminology - are they different terms for a PID loop/controller? It looks like I will be adding a flow meter to the setup instead of relying on passive devices to prevent overrunning the UV. I would...

Thanks, I did review that document and it was very interesting. This is sort of a "medium pure" setup, no idea if there is an actual technical designation for that. We are trying to maintain the output of the R.O. system directly at 5-7 megohms and not going for a complete ultrapure...

Hmm. I haven't kept up with my hydraulic calcs since I first started this project. I'm looking at 330ft of 3" sch80 PVC pipe with (8) 90s and (5) tees. That's 57 PSI drop at the tail end of the loop at 170 GPM, although still only 33 PSI drop to the farthest consumer. I'm estimating this based...

I'm looking at a Flomec TM30SQ9GMD turbine meter with a 4-20ma output module for flow measurement, although they do have an ultrasonic alternative. I like the idea of either passive or pilot operated valves so there's no logic or programming involved to go wrong. Unfortunately the pumps are the...

What I'm finding out is that I should have posted a lot earlier into the process to get help rather than waiting until now. In any case, the good thing is that some changes can still be made based on input from you all. I'm approaching this from a small amount of practical experience and no...

Correct, I want to have a "hot spare" and will probably alternate them every week or so. However, my flow restrictor setup is actually a pair of Flomatic CDK120 valves in parallel, and these might not pass the full 240 GPM until the delta across them is extremely high, according to a curve I...

I will try to get a sketch drawn up. I do have a minimum pressure requirement for one piece of the process equipment, but I can coordinate that with the tank fill operations so that I don't go too low. Pump curve is line "G" here: I am estimating this based on the curve that the valve has...

I'm working on a 10,000 gallon storage tank for reverse osmosis purified water that needs to be recirculated through a UV sanitizing reactor. I would like help on the correct strategy for controlling the pumps in this loop. The loop design is as follows: I have two 10HP centrifugal pumps in...