Comparison Svityaz 4SKM100 vs Nasosy plus 75 QJD 115-0.37

The maximum amount of water that the pump can deliver from the well per unit of time. The choice for this parameter depends on two main points: the maximum total consumption and productivity of the well.

The maximum total consumption is the amount of water that is necessary for the simultaneous normal operation of all points of water intake in the system. Different types of consumers (washbasins, showers, washing machines, etc.) require different amounts of water; exact values can be found in special tables or instructions for specific models of household appliances. And the total consumption can be calculated by adding the indicators of all points of water intake. As for the productivity of the well, this is the maximum amount of water that the well can produce in a certain time without draining it. This indicator is usually indicated in the documents for the well; if it is unknown, before buying a permanent pump, it is imperative to determine the productivity — for example, by trial pumping with an inexpensive unit.

Accordingly, the performance of the pump should not exceed the productivity of the well, and it should be at least 50% of the maximum total consumption of the connected water supply system. The first rule allows you to avoid draining the pump and the troubles associated with it, and compliance with the second guarantees a normal amount of water even with a rather intensive water intake. And, of course, do not forget that high performance requires high power and affects the cost of the device.

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.

The highest pressure that can occur in the line when the pump is running. Note that usually we are not talking about normal working pressure (it is described by max. head, see above), but about short-term jumps that can significantly exceed standard values. The water supply system to which the pump is connected must normally tolerate not only standard values but also the mentioned jumps — otherwise, an accident may occur. Accordingly, the maximum working pressure is useful for assessing how the safety factor of pipes, fittings and other elements of the system corresponds to the characteristics of the pump.

The basic principle or principles by which the suction action of the pump is carried out.

— Centrifugal. As the name suggests, this type of pump uses centrifugal force. Their main element is the impeller installed in a round casing; the inlet is located on the axis of rotation of this wheel. During operation, due to the centrifugal force that occurs during the rotation of the wheel, the liquid is thrown from the centre to its edges and then enters the outlet pipe directed tangentially to the circle of rotation of the wheel. Centrifugal pumps are quite simple in design and inexpensive, while they are reliable and economical (due to high efficiency), and the fluid flow is continuous. At the same time, the performance of such units can drop significantly with high resistance in the water supply system, and the resistance to pollution, although higher than that of vortex units, is still noticeably inferior to auger ones(see below).

— Vortex. Vortex pumps are somewhat similar to centrifugal pumps: they also have a round casing and an impeller with blades. However, in such units, both the inlet and outlet pipes are directed tangentially to the impeller, and the blades differ in design. The method of operation is also fundamentally different — by the name, of it uses the vortices formed on the wheel blades. Vortex units are significantly superior to centrifug...al units in terms of pressure but they are more sensitive to contamination — even small particles entering the impeller can cause damage, significantly reducing efficiency. In addition, the efficiency of such pumps is low — 2-3 times lower than that of centrifugal ones.

— Auger. The main part of such pumps is a rotor in the form of an auger (or several such rotors). The main advantage of pumps of this type is high reliability — they can easily cope even with very sandy water; in addition, the level of noise and vibration during operation is minimal. On the other hand, auger pumps are inferior to the options described above in terms of performance, and their cost is quite high due to the requirements for production quality.

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.

The largest amount of mechanical impurities in the pumped water, which the pump can handle normally. When used with dirty water, this parameter should be taken into account along with the maximum particle size (see above): if the impurity content is too high, the pump may fail even if the individual particle size does not exceed the norm.

The pH value of the pumped liquid for which the pump is designed. This indicator describes the level of acidity of the medium, roughly speaking, how reactive it is to the “acidic” or “alkaline” side: low pH values correspond to an acidic environment, and high pH values are alkaline. Acid and alkaline have different effects on the materials used in the design of various equipment, including pumps. Therefore, when designing parts in direct contact with water, the pH level must be taken into account, and using the pump with unsuitable water is not recommended — this can lead to corrosion, poor water quality and a quick failure of the unit. At the same time, it is worth noting that drinking water wells typically have a pH of 6.5 to 8, and overlapping this range (and even wider) is not a problem. Therefore, this parameter can be called secondary, and in many models, it is not indicated at all.

— 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.

The highest suction water temperature at which the pump can operate normally. For deep well pumps, the water temperature is also important because the pump is constantly immersed in water during operation, and the liquid provides cooling. Therefore, in modern models, performance indicators are usually low — less than 30-35 °C. However, the temperature in artesian wells, usually, is much lower (the only exceptions are regions with thermal waters, but specific equipment is used there).