Max. head
The maximum head is the maximum height to which the pump can raise water during operation (the highest height of the water column that it can support). This parameter describes the pressure created during operation, but since the operation of well pumps is directly related mainly to lifting liquid to a great height, it is easier to use head data in metres than pressure data. However, if necessary, one can be easily translated into another — 10 m of pressure corresponding to a pressure of 1 bar.
When choosing a pump for this parameter, it is not necessary to chase a
large pressure, but it is necessary to take into account several factors.
The first of these is the actual height to which the water must be raised; it can be determined by adding the immersion depth of the pump and the height of the highest draw-off point above the ground. The immersion depth is displayed taking into account the so-called dynamic water level in the well — i.e. distance from the surface of the earth to the water surface during continuous operation of the pump (this indicator is greater than the static level, since when the water is pumped out, its level decreases). The dynamic level is usually indicated in the well passport; the pump should be at least a metre deep underwater, plus a margin of 2 – 3 m should be taken as an adjustment for seasonal level fluctuations. Accordingly, for a well with a dynamic depth of 40 m, supplying a house with
...an upper draw-off point of 6 m above the ground, the total height difference will be at least 40 + 6 + 4 = 50 m.
The second point is the hydraulic resistance of the system. Even with horizontal pipes, pressure is required to move fluid through them; usually, when calculating, it is assumed that for every 10 m of the pipeline, 0.1 bar, or 1 m of head, is required. For a water supply system inside an average house, resistance losses are about 5 m of head (0.5 bar). Accordingly, if in our example the house is located 10 m from the well, then the margin to overcome the resistance should be at least 1 + 5 = 6 m of head.
And the third point is the pressure at the points of water intake because the pump must not only “push” the water to the tap, but also provide pressure at the outlet. Here, the optimal values may be different depending on the situation. For example, let's take at least 1 atm (1 bar), which corresponds to 10 m of pressure.
Thus, in our example, the pump head must be at least 50 m (height difference) + 6 m (resistance) + 10 m (outlet head) = 66 m. Of course, this is a calculation for the most general case; in special situations, the formulas may differ, so it makes sense to refer to special sources for them.Max. particle size
The largest size of solids in the pumped water that the pump can handle without failure. It is one of the parameters characterizing the unit's ability to work with dirty water (along with the content of mechanical impurities, see below): the larger the particles, the more reliable the pump and the lower the likelihood of it breaking down due to pollution. This point is especially relevant for recently drilled wells, where the water has not yet had time to clear.
Suction system
— Single stage. Suction system with one impeller or similar element. Although this design loses to multistage in terms of efficiency and power, at the same time, its characteristics are quite enough for most entry-level and mid-level pumps; at the same time, single-stage units are simpler and cheaper.
— Multistage. This suction system consists of several impellers (or other similar parts that directly provide suction). Such pumps are noticeably superior to single-stage ones, they provide powerful pressure and are less sensitive to impurities. At the same time, multistage systems are quite expensive.
Power consumption
The power consumed by the pump motor during operation. A more powerful engine can provide more head and performance, but these parameters are not directly related: two models of similar power can differ markedly in practical characteristics. Therefore, this parameter is secondary, and more or less unambiguously it describes only the class of the unit as a whole — powerful engines are typical for high-end performant models. But what this characteristic directly affects is the actual power consumption; and with it, in turn, are connected not only to electricity bills but also connection requirements.
