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Thread: 48+34+65=119 according to FMM

  1. #1
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    48+34+65=119 according to FMM

    Screen Shot 2018-09-03 at 2.23.24 AM.png
    I have a 1" manifold off a COR 20 running 32-50% I have a 1" FMM sensor rated at (150-1500gph) on the 3 1/2" TEEs I have a 1/2" FMM sensors each rated at (30-250gph). The 1" FMM reports 119 right now but fluctuates between 115 and 121gph at 32%, I have the following 1/2" sensors showing 48gph, 34gph and 65gph at the time of this writing. I also run a process to clear/clean the lines for 5 minutes each night and run the COR at 100%. The 100% cycle shows a peak of 133gph on the 1", 54, 38 and 73gph in fusion. While not the end of the world, it would seem there would be a way to calibrate the FMM sensors, but, if there is I can't find one.

    Right now the 1" should be 147gph and during the 100% cycle it should be 165gph or a 23% error at 32% pump power and a 24% error at 100% pump power. I'd be inclined to believe the error is because the 1" is below the bottom end of it's scale, at 147, however, the error margin goes up at 165. So... do I have a bad 1" sensor or is this normal deveation?
    Last edited by 1jwampler; 09-02-2018 at 23:24. Reason: add pic

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    I can't really help with your figures, however I am in the same boat as you as I have a 1/4" sensor on my RODI and if I put it on the product water line, where I get 15LPH from (actually measured) I don't even get a reading from on the sensor, so I have put it on the line going into the RODI from the tap and I get 19LPH through it. Now if the sensor is correct, I only have 4LPH of waste water? Yeah, that isn't going to happen... I posted a thread here asking if anyone had this and if there was a way to calibrate the sensors and I got no replies. I am tempted to open a support ticket asking Neptune, but it hasn't really been that much of a concern to me as I only use it to tell me if there is flow or not through the line so Apex knows if the solenoid has failed (if flow is greater than 0 and solenoid is off)

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    Quote Originally Posted by DavidNZ View Post
    I can't really help with your figures, however I am in the same boat as you as I have a 1/4" sensor on my RODI and if I put it on the product water line, where I get 15LPH from (actually measured) I don't even get a reading from on the sensor, so I have put it on the line going into the RODI from the tap and I get 19LPH through it. Now if the sensor is correct, I only have 4LPH of waste water? Yeah, that isn't going to happen... I posted a thread here asking if anyone had this and if there was a way to calibrate the sensors and I got no replies. I am tempted to open a support ticket asking Neptune, but it hasn't really been that much of a concern to me as I only use it to tell me if there is flow or not through the line so Apex knows if the solenoid has failed (if flow is greater than 0 and solenoid is off)
    Yes I also have a ATK and 1/4" FMM, I use #4 on the FMM for the 1/4" sensor, it reports anywhere from 0 to 1.2gph on my nitrate reactor output, but, it actually measures about 8oz in 60 seconds or 3.75gph. Sometimes though it peaks at 4gph, but goes back down quickly.

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    The style and price range of flow meter neptune uses typically have an accuracy spec of 5-10% within their published flow range (I couldn't find the accuracy published for the neptune ones specifically). You also have 2 meters with flow right on the edge or below the published flow range, which significantly increases error. Even if you were within the published range on all 4 sensors, you should expect an RMS error for this situation of either 9% or 17% with a maximum potential error of either 15% or 30%.

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    Quote Originally Posted by zombie View Post
    The style and price range of flow meter neptune uses typically have an accuracy spec of 5-10% within their published flow range (I couldn't find the accuracy published for the neptune ones specifically). You also have 2 meters with flow right on the edge or below the published flow range, which significantly increases error. Even if you were within the published range on all 4 sensors, you should expect an RMS error for this situation of either 9% or 17% with a maximum potential error of either 15% or 30%.

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    As I said in the original post, I agree with your logic (somewhat 23% is really still very huge) because the sensors are at the bottom end of their range, however, as you increase flow the sensors all move away from the bottom end of the range and the error is worse. Also my guess is if I measure each output I'm going to see more like 250-300 GPH delivered back to the tank. As I also said this is a COR 20 running has high as 100% with about 6' of lift, it should be nearing 500-600gph before loss from bends, UV, etc. So if no one has any good explanation behind the kit not agreeing with itself and getting worse as you move more toward the middle of the range, I'll do a quick 1Gal flow test at the tank for an exact number back, again, best guess from looking at flow for over 20 years is 300gph, which would be 100% deviation.

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    Frequent Contributor zombie's Avatar
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    Are the arrows on the sensors pointing the right direction?

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    Quote Originally Posted by zombie View Post
    Are the arrows on the sensors pointing the right direction?

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    Yes, I'm very anal about things like that, I always take a sharpie and draw arrows in an obvious color (silver in this case) matching the case molded arrow, so after cleaning, it's very obvious how it goes back.

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    I would check for obstructions in the sensors and make sure the jack is plugged all the way in if you haven't already.

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    Quote Originally Posted by zombie View Post
    I would check for obstructions in the sensors and make sure the jack is plugged all the way in if you haven't already.

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    yep... that's next on the list, but, because of the BSPT it was difficult to plumb and get plumbing if I break something, the above said, the core is behind a 14x7x3" sponge in the sump, so not likely anything big, and it's only been installed for a couple of weeks and it's always had this flow. So.... obstruction is a Hail Mary, but certainly possible.

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