This selection of the pump should be started after the well is drilled and will get the passport well. This document is issued by an organization which deals with drilling for water. The passport must necessarily bear the following characteristics necessary for the proper selection of pump:
- Yield (productivity wells in m3 / h);
- Static water level;
- The dynamic water level;
- Total depth;
- The size and depth of the filter well;
- Diameter of the hole.
With these data, you should check the source of water supply (ie wells) to meet its hydraulic characteristics of the required maximum flow. Maximum flow rate should not exceed the well discharge. Ideally, the maximum flow rate to select a 5-10% lower production rate. If you do not, the work of the pump will lead to a reduction of the dynamic water level below the suction of the pump, which is fraught with the work of the “dry”. If the pump is no protection against “dry run” this will damage the unit. If the protection is installed, it will spontaneously fall off at a level below the selected value, repeat the same switch will be made only after the restoration of water level in the well at least until the dynamic level. This can take quite a long time, during which you will be without water.
There is one negative point: the possible erosion of rocks in the area of the filtration area and, as a consequence, filter plugging wells. Work in this mode can lead to obstruction and even destruction of wells!
So, after determining the maximum flow rate and consistency of its parameters well, one must calculate the desired maximum pressure. This can be done by the following formula:
H = Ptapx10, 2 + Hgeo + EHf,
Where Ptap – pressure that is necessary to create the system. Usually take 2-3 bar (familiar to us pressure in the urban network);
Hgeo – surveyor pressure. The difference in elevation from the dynamic level to the highest point of water pumping in meters of water column;
EHf – the amount of head loss along the pipeline (see Table 2) and local loss (head loss at bends, tees, gate valves, etc.).
However, local losses can be taken equal to 15-20% of the loss in length. Also be taken into account in the system filter. Loss of pressure on him too belong to the local losses, but their value can be quite large (on average, they range from 0,5 to 1,5 bar), depending on type and size filter. Clarify the meaning can be on your passport for a fixed filter.
