How to empty a water sump using two float switches and a solenoid valve

Discussion in 'The Projects Forum' started by manofgresley, Jul 2, 2014.

  1. manofgresley

    Thread Starter New Member

    Sep 13, 2010
    6
    0
    Hi all.

    I need a little help, i am building a water vac suction pump, to empty water from a pond, this is how i want it to work -

    1 Suction hose is placed into the water.
    2 Pump is switched on manually
    3 pump sucks up water into a sump,
    4 When water rises to top of sump, it lifts a Float switch and the pump motor turns off.
    5 Simultaneously, a solenoid drain valve opens.
    6 Sump starts to drain out.
    7 When sump is empty, another float switch at the bottom of the sump energizes, closes the solenoid valve and restarts the pump cycling over and over again.

    The pump motor is 240 volt AC.

    Can anyone help with a circuit diagram please.

    Regards

    Ray
     
  2. sirch2

    Well-Known Member

    Jan 21, 2013
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    Sounds complicated, is there a good reason that you can't just use a commercially available submersible pump to pump the water to wherever the sump drains?

    Not wanting to nit-pick bit I've always understood the term "sump" to mean the lowest point and things are normally pumped out of a sump - i.e. a sump couldn't be free-drained by a valve. Anyway, some clarity on the arrangement may be helpful.
     
  3. Dodgydave

    Distinguished Member

    Jun 22, 2012
    4,998
    745
    it can be done with a 555 timer,
     
    Last edited: Jul 2, 2014
  4. inwo

    Well-Known Member

    Nov 7, 2013
    2,433
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    Or a relay.
     
  5. djsfantasi

    AAC Fanatic!

    Apr 11, 2010
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    A pond (even a garden pond) may have several inches of silt on the botton, which would quickly clog a submersible pump.Actually, this is a good idea, as I need a similar solution for next spring
     
  6. sirch2

    Well-Known Member

    Jan 21, 2013
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    Stand the submersible pump on a brick? Or use a pond pump, I used to have a pond in the garden (it came with the house) in which was a small pump to run a little fountain. The pump had a big foam filter around the intake and never seemed to clog. I have also worked with huge submersible pumps in sewage works - you should see the crap they have to handle ;-)

    Seriously though I suppose what I was interested in was why not just pump out the pond, why all the complexity?

    If the requirement is to separate solids from the water then the normal approach is to use a settling tank where the water is pumped into a tank and flows out over weir at the other end, the time taken for the water to move across the tank allows for solids to settle - so the bigger the tank or slower the flow the more settling.
     
    Last edited: Jul 2, 2014
  7. alfacliff

    Well-Known Member

    Dec 13, 2013
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    there are submersable pumps that can handle silt, they are called ejector pumps and are used in basements to lift sewage from a holding pit in the basement. if they can chop and pump that, they should work with silt.
     
  8. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    Why do you have to let the sump fill before letting the water out? Why is a drain valve needed?
     
  9. djsfantasi

    AAC Fanatic!

    Apr 11, 2010
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    He is using a wet/dry vac as his pump. It needs a closed container to maintain vacuum (drain valve closed), but when it fills, it has to be manually drained (or drain valve open). The OP is trying to automate this process.
     
  10. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    Post deleted.
     
  11. wayneh

    Expert

    Sep 9, 2010
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    OK, well the wet vac might have it's own float switch to turn itself off when full? This leaves only the need for detecting when the drain valve needs to be closed to restart the process.

    What about when the pond is empty. Just a manual shutoff?
     
  12. djsfantasi

    AAC Fanatic!

    Apr 11, 2010
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    Maybe, but not all. Mine doesn't and it would be particularly useful feature! I use the wet feature most often when my basement gets water. I tell when its full because the motor starts whining. There is a float ball, that only closes off the intake port. The resulting increase in load causes the motor to strain and whine.

    I suspect the OP's vac also has this limitation and his intent is to use the same vac for his pond.

    Good point of the empty pond case. As requested, it would leave the system in a running state...
     
  13. MaxHeadRoom

    Expert

    Jul 18, 2013
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    If this is an impeller pump, as most are, closing the intake port removes all load and hence lowers the current. ;)
    Same as blocking a vacuum inlet (or outlet) removes the load and the rpm's soar if it is a series motor.
    Max.
     
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  14. wayneh

    Expert

    Sep 9, 2010
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    I'd be tempted to use a load cell to detect both fill levels. The controller would then have just two states: 1) vac on, drain valve closed and 2) vac off, valve open.

    A scupper valve - a ball in a cage held near the drain hole - would allow just turning the vac on and off. Without vacuum, the water would push the ball away and gush out. Under vacuum, the ball would be pulled into the hole and hold back the flow.
     
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