Does increased resistance impacts return pumps lifespan?

Discussion in 'Pumps and Waterflow' started by Bendor, 3 Jul 2013.

  1. Bendor

    Bendor

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    This may be a dumb question but is possible to strain a pump too much? All return pumps are pushing against pressure due to the height of the return pipe even though it appears minimal because the valve is fully open and resistance is "low". Closing the valve somewhat will decrease flow and simulate a higher head height that needs to be achieved but does that really put the pump under strain? I know it causes more turbulence in the impeller chamber because only some of the water is pushed into the return pipe due to resistance and the rest just swirls around in there but does that strain the pump or is it just audible turbulence? If the impeller spun around in a closed chamber with no flow at all and only local turbulence does that put strain on the pump or does it just stop the impeller magnet from turning as fast as it could with no resistance? There aren't any gears involved so no real strain or is there?
     
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  3. dallasg

    dallasg Moderator MASA Contributor

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    My take is that all pumps need some back pressure, so most pumps have a head rating , eg 1000l @ 5m and 3000l @ 1m, so if I am pumping 1.5m I can use a valve to apply similar pressure that doesn't exceed the max head pressure
     
  4. Bendor

    Bendor Thread Starter

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    I agree but max head just means the max height the pump can push water to with a set diameter pipe. If I had two 5000l at 1m pumps but my two tanks were 1m and 3m high respectively. Both would flow, one would obviously flow slower but would the one that pumps the water higher be under more strain and therefore not last as long?

    I don't think so. I don't think more height equals more strain on the motor just less flow.

    @Locke
     
  5. dallasg

    dallasg Moderator MASA Contributor

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    The height applies more pressure on the pump and the pump will still try pump at 100% , so using a valve does the same
     
    Last edited: 3 Jul 2013
  6. LCornelius

    LCornelius Moderator

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    Jip, if you pump water 5m into the air the back pressure is the same as using a valve to limit it the flow.

    Remember that using bends in your plumbing all account to head loss and back pressure.
     
    Last edited: 3 Jul 2013
  7. Bendor

    Bendor Thread Starter

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    I agree with both of you. My question is does it put more strain on the pump motor and decrease it's lifespan? I don't think so because the forces in the pump are uncoupled so not closing the valve because you don't want to "strain" the pump is actually not relevant. If you need less flow, close the valve and it won't affect the lifespan of your pump.

    Or not?
     
  8. Bendor

    Bendor Thread Starter

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    The reason I'm asking is because Locke has problems with micro bubbles n his sump and it appears slowing down his return would fix it wih the least hassle but putting strain on the pump is a concern. I'm just wondering if that is in fact the case.
     
  9. dallasg

    dallasg Moderator MASA Contributor

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    What about adding a t piece, one to DT and one back to sump with valve on, that way can regulate with no strain.

    But to your original Q, I can't see it being an issue as long as the pressure applies allows the minimum flow through the pipes
     
  10. RiaanP

    RiaanP Moderator

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    The newer DC pumps do run slower when the head pressure increases. It is part of their design, the use less power if the outlet is restricted. Maybe it is a bug in their design, but it is marketed as a feature...

    Anyway, DC pumps do not like a lot of bends and high return lines, or incorrect pipe thickness.
     
  11. RiaanP

    RiaanP Moderator

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    AC pumps, there is no direct coupling between the impeller and the motor. So it should not put any extra wear directly on the housing. Although the magnet would or could run slower than the electrical coil inside the pump motor. So the question should be if that would have any impact on the coil. Submerged pumps should not have issues due to heat build up, external pumps might. As long as the magnet can run at 100% speed while the outlet is blocked, then I do not see an issue. But what will happen if it does not run at 100%? I do not know.
     
  12. deadmeat2016

    deadmeat2016 Wouter

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    I have also thought about this alot, most people put a valve on the plumbing directly after the pump outlet which does cause more back pressure on the pump and I don't understand why its done.

    My method, i think Dallas has the same type of design.
    start of sump
    ;;;;;;;;;;;;;;;;;;;;Valve;;;; T-piece;;;;;;;;;;;;>to DT
    l " " l
    l " waterflow through sump " l
    l " >>>>>>> " l
    l V Return pump l <------Sump and return pump
    l___________________________________l_

    The return pump has a t-piece which directs the flow towards the front of the sump and to the DT. The piping going to the front of the sump has a valve, close it, you have max power to your DT, open it slightly and some of the flow is directed back to the front of the sump and less flow to DT.

    Result, no extra back pressure on the pump, the flow is just directed back to the front of the sump
     
  13. deadmeat2016

    deadmeat2016 Wouter

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    That didnt go as planned, but i hope the idea is clear
     
  14. Bendor

    Bendor Thread Starter

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    As mud...
     
  15. mandarinman

    mandarinman

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    Repeat
     
    Last edited: 4 Jul 2013
  16. mandarinman

    mandarinman

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    Repeat
     
    Last edited: 4 Jul 2013
  17. mandarinman

    mandarinman

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    Last edited: 4 Jul 2013
  18. deadmeat2016

    deadmeat2016 Wouter

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    rahh, basically the flow in the sump is from point A to point B, the return pump is at point B, incoming DT water at point A, ok

    What I see most reefers do
    Most people seem to just add a valve as the first thing the returning water encounters, closing the valve less power but puts alot of back pressure on the pump.

    the super method which some reefers have also discovered! but I did it first :tt2: kidding :)
    At point B, the return pump does its thing but a T-piece is fitted as the first plumbing part the water flow reaches when on the return journey.

    At the magic T-piece, flow comes in and is diverted into two directions.

    One of the 2 possible outlet routes is plumbed to the DT - the final goal, yay

    the other is plumbed to direct the flow back to point A, remember point A and B....yes

    This is the really magical bit which will have you gasping............ :thumbup:

    The diversion which directs the flow back to point A, is fitted with.......a valve

    Close the valve, all the flow is directed towards the DT - FULL POWER

    open the valve, the water will follow the most gravitationally stable route, avoiding the long journey up to the DT and just ending up at following the route to point A - MINIMUM POWER


    - depending on the thickness of the pipes, strength/tourque of the pump, height of DT return line, the flow pressure to the DT will definitely decrease and usually stop but not always.

    The valve can now be adjusted to aquire the desired return flow rate.
     
  19. RiaanP

    RiaanP Moderator

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    OK
    but the original question is still not answered.
    Does increased resistance strain return pumps?

    solutions are given. But the question still remains.
     
  20. Bendor

    Bendor Thread Starter

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  21. RiaanP

    RiaanP Moderator

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    I got a Waveline DC10000 as a return pump. Line splits with a T piece out to the side. The top part go to display but got a ballvalve in line. The other line goes to my remote filtration system. Consisting of a frag grow out tank - 220L rocktank and 220L remote DSB.
     
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