Emptying a lost well

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evin1969
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Emptying a lost well




by evin1969 » 30/03/08, 14:06

Hello,

We had our septic tank emptied and the employee pointed out to us that our lost well is full (blocked?).
As he asked for 300 euros to empty it, we thought we could do it ourselves and we bought a Karcher GP40 pump (3,5 bar, height 40m and 9m).

When we wanted to start it, we followed the instructions and despite that no way to pump water from the well.
We put a hose with strainer and non-return valve in the well water, the pump 1 meter from the inlet and a garden hose at the outlet.
The pump was primed by filling it with water and when it started up, it emptied completely. After a dozen priming, the water finally reaches the inlet of the pump ...
Then nothing !!! the water no longer moves at the inlet and the pump only drains the water that is put in to prime it.

We have never used this kind of material and maybe there is a simple thing (even very simple) that we did not do.
Can you help us...
Thank you
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by Rabbit » 30/03/08, 14:38

It is preferable to use an empty cellar pump for charged water.
This pump starts directly to pump water. Boredom is
that you have to find a place to drain the water that usually doesn't
not smell like rose.
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evin1969
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by evin1969 » 30/03/08, 14:48

We did not take the empty cellar pump, because after emptying the lost well, we will use the Karcher to water the garden using the water from the rainwater tank (because the pump installed for this tank does not is not very brave).

But I still don't understand why I can't pump? : Lol:

Our water does not smell because it seems that it is the heavy rains of the last few months that have filled the well lost ...
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by elephant » 30/03/08, 15:41

in general the suction effect of a pump is of the order of 1 or 2 m of level difference. Your pump is too far from the water surface. The distances you indicate are after the pump.
In any case, the theoretical maximum level of aspiration of a water pump is of the order of 10,33 meters if the vacuum it causes is perfect. (= increase in atmospheric pressure)
in addition, the suction flow must correspond to the pump flow, otherwise it will prime.
Your Karcher pump is probably intended for pressurized rather than vacuum supply
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evin1969
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by evin1969 » 30/03/08, 18:45

The pump is placed on the lawn, just one meter from the surface of the water (the well is complete!).
So I can't put it any closer.
I put a hose in the well with a length of 7 meters and 10 meters of garden hose at the outlet of the pump.
However, it is a sprinkler pump and therefore, I think fit for the use I want to make of it.
But no way to make it work ....

Either I am not good or I did not understand something : Lol:

I am confused...
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by bham » 30/03/08, 19:01

I know this very nerve-wracking problem.
1- Fill the pipe with water with the strainer at the end and check outside the well that the valve is tight.

2- If 1 is verified, it may be that at a depth of 7 meters there is so much dirt (vase for example) that it clogs the strainer. To check it, reassemble the hose at least 1 m and try again.

FYI, pumping into a well full of dirt with a strainer and non-return valve may clog the latter which then ceases to play its sealing function. It's annoying when you want to pump at regular intervals because the pump is primed.
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by Christophe » 30/03/08, 19:06

+1/2 with elephant because a pump can self-prime more than 2m.

If I understand the problem correctly: your pump is 7m high from the surface to be pumped?

In this case I fear that this height is too great and that you will have to use a submerged pump and not suction.

The maximum and "absolute" height of a self-priming pump, assuming that it makes a perfect vacuum, is the NPSH which is worth 10,33 m in reality depending on the quality of the pump, it is rather around 8m and you don't is not far ...

What does the manual say about the self-priming height?

NPSH (Net Positive Suction Head) or Absolute net head

A pump has a maximum suction capacity which is the value of the vacuum it can produce. This characteristic varies depending on the type and technical design of the pump.

Theoretically, the maximum suction height, in a cavity where absolute vacuum reigns, is equal to atmospheric pressure, that is to say 1013 mbar at sea level (10,33 m of water). It gradually decreases as the altitude increases.

In reality this height is limited, not only by the pressure drops in the suction line but also by the physical properties of each type of liquid.

What is NPSH?

NPSH is simply a measure to quantify the available suction head to avoid vaporization at the lowest pressure level in the pump.


http://www.thermexcel.com/french/ressou ... lateur.htm
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by loop » 30/03/08, 19:59

Hello

I have already encountered a similar phenomenon with my Gardena pump which has the same characteristics, for the same type of use.
Indeed, it is not self-priming so it is necessary to correctly fill the suction pipe making sure that no air remains
Then, the pump body must also be completely filled so that it starts immediately in the water
Regarding the power to raise the water, it can largely draw at a level of several meters below that of the pump
At -9m, the flow must be zero (not verified)

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by Other » 30/03/08, 23:07

Hello

A normal centrifugal pump with a priming tank should not be expected to draw more than 7 meters beyond that it takes an eventuri

In the most likely case it is that once primed, you consume too much water it will defuse

You must either place a valve and control the flow or a reduction at the pump outlet to leave a certain pressure in the pump to prevent it from coming out too much. This makes an air pocket at the inlet and it defuses, this and even more visible if the water levels to be pumped are deep

Andre
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by elephant » 30/03/08, 23:12

That's it: this pump at such a rate that the suction is not powerful enough and it defuses because the water does not arrive on time.
Only a submerged empty cellar pump could do the trick.
(or else, you would need a second power supply which is cut off once the pump is primed, but 7 meters is limit)

It will soon cost more than 300 euros ..... : Cry:
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