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Another water pump automation project (suggestions ?)

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    #61
    Re: Another water pump automation project (suggestions ?)

    Originally posted by Dannyx View Post
    I once encountered a magnetic level sensor of the same description in an ironing station. It was used to sense when the water level in the tank dropped too low or if the tank was removed entirely. It had a magnet stuck inside a piece of plastic inside the tank that went up and down with the water level. Water had gotten into the plastic shell and corroded the magnet which no longer "worked". The reed switch that sat on the outside wall of the machine near the tank no longer closed, so the station would always think the tank is missing and wouldn't run. I couldn't get the magnet out without breaking the tank open, so the only solution was to replace the whole tank and that got it going again.

    In the case of these large tanks, which I assume are fairly beefy plastic, a stronger magnet would probably be required to trigger a reed switch on the outside...which would also have to be water-proof.
    Hall Effect switches have been used in crank shaft position sensors for years. Many millions and millions of cars and trucks have them. Although there may be a problem in very few vehicles, I would say their success rate is around 99% for several years. Unlike your pump a crank shaft sensor has to turn on and off several times a minute. These sensors can work in dirty environments successfully. I would say there has to be many ways to successfully enclose a natural magnet in a float so as not to compromise it.
    The tank you talk about replacing tells me whomever designed the float and the magnet inside most likely needs to go back to design school because components fail and tank lids need to be taken off if only for cleaning the tank inside, tanks get dirty. I sure would not use a reed switch and magnet to close it on the outside of the tank. One job i had while I was attending College was as a Security Alarm installer. The magnet and reed switch are used in that industry. They fail quite a bit of the time. You need to look up Hall effect switches. They will acquire a small amount of current from the magnet when it comes in line with it. I would say that the hall effect switch would be places at the top of the water line where water pressure is not great. It actually could be places above the water line. The top of the float in the tank could also be place above the water line. So even when the float went down it would still be above the water line. One could actually place the Hall effect switch inside the water tank in this case. Depending on plastic of the tank one could both screw into the tank and also have a plastic adhesive on the mounding bracket for the Hall Effect switch The Hall Effect switch then could be mounted with stainless steel screw and nut on to the bracket so it could be removed easily. Of course, one has to have a removable Lid on the tank to do this. On then could drill a hole in the lid so the wires to the hall effect switch can exist. The wires would be sealed with food grade silicone caulk where they exist the tank. If the tank does not have a lid one could make a lid for it. Simply mark a circle around the tank near the top on the side of the tank. Use a plunge cutting tool and follow around the marked circle. Then buy food grade gasket maker. Line the cut top with this gasket maker. Then put the top lid on after the appropriate time and wait for a little more time then secure the top lid with stainless steel screws.
    If cutting the whole top off is too much, then just cut a section off big enough for a human to get in the tank and clean it. Use stainless steel hinges to secure it to the top and a side hinge. use the gasket maker to fill the space where cut and then tape over the gasket maker.

    Of course, some big manufacturers who want to cut cost like Ford Motor Company will design something that is almost impossible to replace without pulling the engine. I believe a friend of mine had a 7.3L Diesel sensor that went bad, and it cost over $700 to replace it. Luckily the truck was still under warranty.
    Last edited by keeney123; 08-07-2022, 11:01 PM.

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      #62
      Re: Another water pump automation project (suggestions ?)

      Originally posted by redwire View Post
      Those water tanks at 1,000L/275gal are large weight up to 1,060kg/2,332lbs.
      But they have a small 6" fill cap lid which makes putting sensor and fill pipe inside a hassle.
      .. uh make sure the stand is good for a ton, the legs might sink into the ground and the tank fall over.

      I noticed the two tanks are connected together at their outlet, but a closed valve is between them for some reason. It would be simpler with them connected together.

      Did you finish the plan for the pump logic? An ESP8266 is really good and what I'd use for something small and low cost like this, with a webpage. Before, I thought you were doing something industrial in a plant where the tanks and pumps are much bigger and a PLC is standard use.
      Yeah, I'm not sure how the chap was planning to get those floats inside the tanks, since I knew from the very start, just by looking at them, that they only have a very small lid, unless maybe he enlarged the holes some more....

      Too bad he already bought the floats, since I would've proposed the hall sensor variant. I'm sure there exist pre-made devices, not just the bare sensor.
      Wattevah...

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        #63
        Re: Another water pump automation project (suggestions ?)

        how are the tanks vented?

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          #64
          Re: Another water pump automation project (suggestions ?)

          Originally posted by stj View Post
          how are the tanks vented?
          Through the top lid. The inlet pipes at the top are not caulked in place, so there's plenty of room around it for air to get it. Since this is not for drinking, it doesn't matter too much if nasties get inside too, though it may eventually get to a point where the dirt clogs up the pipework.....
          Wattevah...

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