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Thread: Flow Switch

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    Extreme Koi Member Rank = Rokusai Pointy's Avatar
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    Flow Switch

    Hi,

    I am currently looking at ways of fitting a flow switch to my main pump line. While my Raspberry PI pond monitor system has been working well over the last few years, I have had the odd problem with sticking relays, so thought it would be useful to know when the pump is running, then the system can alert me if the main pump stops.

    I quite like the look of this flow switch, it's just a question of how to integrate it into the pipework. The two obvious positions are shown below, with A being the preferred one, as it's less likely to get knocked or kicked and offers a couple of connection options. There is about 6" between the rubber boot and bend at point A and 7" between the swept and 35 degree bends at point B.

    flow sw positions.jpg

    The simplest option is to use a 2" tee piece, cap off the tee and somehow fit the flow switch in the cap. The question is,how much will it affect the flow? I can't see any dimensions for the paddles but looking at the images, would guess they are about 15 - 20mm wide. Bearing in mind that the main line reduces down to 1.5" at the UV, do you think the switch will affect the flow rate dramatically?

    If so the other, much trickier option is use a piece of 3" pipe between the Nexus and swept bend and try and fit the switch through the side wall some how. I would then have to replace the rubber boot with a 4"-3" one, and reduce down to 2". I am not even sure if that will be possible with the space I have and it will also be much more expensive, especially as i already have a 2" tee piece for some reason.

    Any thoughts or feedback, welcome.



  2. #2
    Extreme Koi Member Rank = Hassai Frich's Avatar
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    the paddles would be around 12-14mm looking at the pictures.
    so it would case abit of flow reduction

    but what about using a float in the system ? i have 1 for each pump on my drum filter, so that if they get activated i know the filter isnt working (clean side of the drum gets drained by the pumps) and then shuts off the pump. an at the same time i am monitoring the current running to the pumps, so that i know if the pumps are running.
    https://www.ebay.co.uk/itm/LEM-CAS-6...cAAMXQPatTIjvb

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    Extreme Koi Member Rank = Rokusai Pointy's Avatar
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    Quote Originally Posted by Frich View Post
    the paddles would be around 12-14mm looking at the pictures.
    so it would case abit of flow reduction

    but what about using a float in the system ? i have 1 for each pump on my drum filter, so that if they get activated i know the filter isnt working (clean side of the drum gets drained by the pumps) and then shuts off the pump. an at the same time i am monitoring the current running to the pumps, so that i know if the pumps are running.
    https://www.ebay.co.uk/itm/LEM-CAS-6...cAAMXQPatTIjvb
    Hey Frich, how are you. I remember your build as it started about the same time as mine. I'll have to try and dig up your build thread.

    I think the flow switch is a no go as I also read you should have 10 x the pipe diameter straight pipe before and after the switch, which is not possible for me.

    I think an easy solution is to monitor the NC contacts on the relays for a voltage, which will let me know if a relay fails to open or close. I'll look at the current sensing too.

  5. #4
    Extreme Koi Member Rank = Hassai Frich's Avatar
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    hi
    i haven't been around much, as i have been busy (as allways) but the last 2 years i have been working in japan, Korea and Australia, so i haven't been home much

    my electronics are not in the build thread, since it's still an ongoing job
    but it's based on a custom circuit board controller without any "brain", since i have not found the arduino's or raspberry's to be reliable enough. i am constantly modifying it thou. the current version supports monitoring of water levels and running the drum filter (didn't like the way the Inazuma standard controller worked). it also switches on and off the UV if anyone opens the filter, and stops the pumps in case the filter gets blocked (with visual alarm)
    then i have an arduino collecting data, that is then transmitted to a raspberry to display on a webpage. but that is only for data collection.

    as for your pump, if you only monitor the relay. it will only tell you if the pump is getting power, not if it is actually running. so if the pump gets blocked or maybe breaks, you will have no way of knowing.
    if you monitor the current, you can see if the pump is blocked (high current) or if it is running dry (low current). both values are of course compared to nominal value. if you fine tune it enough it will tell you if your pump bearings are getting worn. (slow increase in current over time)

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    Extreme Koi Member Rank = Rokusai Pointy's Avatar
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    Quote Originally Posted by Frich View Post
    hi
    i haven't been around much, as i have been busy (as allways) but the last 2 years i have been working in japan, Korea and Australia, so i haven't been home much

    my electronics are not in the build thread, since it's still an ongoing job
    but it's based on a custom circuit board controller without any "brain", since i have not found the arduino's or raspberry's to be reliable enough. i am constantly modifying it thou. the current version supports monitoring of water levels and running the drum filter (didn't like the way the Inazuma standard controller worked). it also switches on and off the UV if anyone opens the filter, and stops the pumps in case the filter gets blocked (with visual alarm)
    then i have an arduino collecting data, that is then transmitted to a raspberry to display on a webpage. but that is only for data collection.

    as for your pump, if you only monitor the relay. it will only tell you if the pump is getting power, not if it is actually running. so if the pump gets blocked or maybe breaks, you will have no way of knowing.
    if you monitor the current, you can see if the pump is blocked (high current) or if it is running dry (low current). both values are of course compared to nominal value. if you fine tune it enough it will tell you if your pump bearings are getting worn. (slow increase in current over time)
    I'll have to look at the current sensing, but as all of my problems have been caused by relay boards, including 1 burnout due to moisture/bad connection,(perhaps I need a couple of thermistors too ) I thought it would be the simplest solution for now.

    burnt relay.jpg

    Also I only have 8 x aux connections on my custom PI PCB and I believe these are all digital anyway. However the Teensy LC has 13 analogue inputs and as I have never used the RGB LED strip lighting plus the fact that it no longer works anyway, I could maybe use the Teensy inputs to monitor currents and talk to the PI via 12C.

    I want to completely remake the enclosure for my electrics anyway, to make it more maintenance/upgrade friendly, so I will look at all my options when I do that.

  7. #6
    Extreme Koi Member Rank = Hassai Frich's Avatar
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    you definitely have way to much moisture in your enclosure. and that seems to be what is causing the problem.

    get a proper IP44 enclosure as a minimum (IP65 if you can get it) they are not that expensive, but it will save a lot of money in the long run.
    the current transducer i linket before sends out 0-5V (5V at 6A) so it's very easy to use with most programmable boards (the PI runs on 3,3V thou)

    personally i use DIN mounted Relays that are rated to 10A at AC3, AC classification is used to define what the relay can handle when it comes to inductive loads.
    a relay rated at 10A AC1 is only meant for loads like a heating element or a light bulb, when you are running inductive loads like a motor, you need to use an AC3 relay.
    the relays on that relay module are AC1 (when nothing is listed it is allways AC1) but since they are rated at 10A and your pump is most likely drawing less than 5 they do last for a while.
    in this case however the failure is 99% sure moisture, you can see the corrosion on all the screws, and that is also attacking the terminals, once they start to corrode you get a bad connection, and that generates heat, so the whole thing melts

    not sure what he rated power of the screw terminals are thou, might be that they aren't rated for 10A

 

 

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