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Run submerged waterfall pump without water, what will happen

Run submerged waterfall pump without water, what will happen

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  #1  
Old 08-15-07, 03:44 PM
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Exclamation Run submerged waterfall pump without water, what will happen

In the manual of the submerged waterfall pump...
It says, don't run motor without water.
If the motor run without water, what will happen to the pump?
 
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  #2  
Old 08-15-07, 03:51 PM
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I'd post this in the plumbing forum.

If I had to guess you would ruin the seals on the impeller shaft.
 
  #3  
Old 08-15-07, 03:57 PM
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Wink

Water wont flow.

Joking of course.
 
  #4  
Old 08-15-07, 04:15 PM
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I asked this because sometimes there are blackout of electricity and it drains all the water out. And when electricity comes back at the unholy hour of the night, the motor may run without water.


If this happens to the motor ,What can happen to the motor?

Can the motor be repaired?
 
  #5  
Old 08-15-07, 05:20 PM
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it could damage the motor if it actually depends on the water to cool the motor.

the seals or bushings that depend on the water to either cool or lubricate them would be damaged as well.

just about anything can be fixed...for a price.

sounds like you need a motor control circuit that would not allow the motor to restart once power has been interupted until you manually restart it.
 
  #6  
Old 08-15-07, 05:33 PM
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I was taught in the Navy the impeller would seize up. Shallow well pumps often use a foot valve to keep it from loosing prime. I can't recall seeing one for a fountain pump but if it is submerged it shouldn't loose prime. After all submerged implies under water.
 
  #7  
Old 08-15-07, 05:39 PM
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Why not a float switch, similar to a septic tank pump? No water in the pit....NO RUN. Since the water is depended on to cool the pump, Bushing failure would be first. the Motors are usually Overload protected, and are usually safe from Catastrophy, If it interrupts before the bushings and seals quit.If youve been lucky so far, dont make a habit of it.
 
  #8  
Old 08-15-07, 07:09 PM
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Originally Posted by herbolaryo View Post
I asked this because sometimes there are blackout of electricity and it drains all the water out. And when electricity comes back at the unholy hour of the night, the motor may run without water.


If this happens to the motor ,What can happen to the motor?

Can the motor be repaired?
I don't understand, my water fall has a resorvor of water that it recycles.
So when the electric goes out it just stops flowing and restarts flowing when
electric is back on
 
  #9  
Old 08-15-07, 07:28 PM
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Originally Posted by ray2047 View Post
I was taught in the Navy the impeller would seize up. Shallow well pumps often use a foot valve to keep it from loosing prime. I can't recall seeing one for a fountain pump but if it is submerged it shouldn't loose prime. After all submerged implies under water.
Hey, I'm just going with the concern the OP asked about. I don;t see why there would be a problem either since the water would settle to the pump (that's what a sump is for) and there should be plenty of water but OP states there is no water so maybe there is something else going on that we are either missing or can;t see because the OP did not explain it.
 
  #10  
Old 08-15-07, 09:07 PM
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Nap, my post was directed to the OP. Sorry if you thought I was aiming at you.
 
  #11  
Old 08-15-07, 09:38 PM
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Nah, no apology needed and mine wasn't so much directed at you either. Everybody pretty much is wondering how OP ends up with no water at the pump when a submersable pump would (should) set in a pool of water whenever it isn't running.

Your post just made it very clear what everybody else appeared to be thinking.

Curious how the water gets to the pump to begin with.
 
  #12  
Old 08-16-07, 04:21 PM
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Exclamation

The pump is located downstream the falls with a float switch to top off the water when it gets low due to normal evaporation of water. There is a pond at the lowest point of the falls where the pump is submerged.

However, there are unexpected electricity blackout which empties the whole pond. Since the float switch can not keep up , during the time when electricity just came back, it sucks up air.

The pump sucking air only happen during occassional electricity blackout.

The humming noise occurred after that time eventhough I cleaned the filters and the motor "blade" of debri.

So what can be the cause of the hum noise in the pump and how to fix that?
 
  #13  
Old 08-16-07, 05:03 PM
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what humming? I believe this is the first time you mention "humming".

So, does this mean the motor does not run? Does it run but hums?

Give us a clue.
 
  #14  
Old 08-16-07, 09:22 PM
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Smile

Probably not the case here as one of the pros on this thread would have caught it, but many motors are designed to operate under a certain "load" (like air conditioning blower motors inside a housing) and when they are operated sitting on a bench for a bench test the amp draw clearly goes higher than what the rated RLA is. As an HVAC tech I do know this from experience.
 
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