Comparison Pedrollo JSWm 2C vs Nasosy plus DP750A

The maximum volume of water that the device can pump in a certain amount of time. It is one of the key specs of any pump because characterizes the volume of water with which the device can work. At the same time, it does not always make sense to pursue maximum performance — after all, it significantly affects the dimensions and weight of the unit.

Some formulas allow you to derive optimal performance values for different situations. So, if the pump is designed to supply water to water intake points, its minimum required performance should not be lower than the highest total flow rate; if desired, a margin of 20-30% can be added to this value. And for sewer models (see "Suitable for"), everything will depend on the volume of wastewater. More detailed recommendations for choosing a pump depending on performance can be found in special sources.

The maximum head generated by the pump. This parameter is most often indicated in meters, by the height of the water column that the unit can create — in other words, by the height to which it can supply water. You can estimate the pressure created by the pump using a simple formula: every 10 m of head corresponds to a pressure of 1 bar.

It is worth choosing a pump according to this parameter, taking into account the height to which it should supply water, as well as adjusting for losses and the need for pressure in the water supply. To do this, it is necessary to determine the difference in height between the water level and the highest point of water intake, add another 10 to 30 m to this figure (depending on the pressure that needs to be obtained in the water supply), and multiply the result by 1.1 — this will be the minimum pressure required.

The highest pressure that the pump is capable of creating during operation. This parameter is directly related to the maximum head (see above); however, it is less obvious, and therefore, it is indicated rarely.

The main division in this parameter is related to whether the pump can remove air from the suction line. This, in turn, determines the features of starting the unit.

— Self-priming. Self-priming pumps include all pumps that do not require the complete absence of air in the suction line at startup — it is enough that the pump itself is filled with water. Accordingly, such models are less demanding and normally tolerate air entering the line. However, this requires a reliable design that can normally withstand water hammer, which accordingly affects the cost of the unit.

— Priming. Pumps with this device can only work normally when both the unit body and the suction line are filled with water. If air enters the line, it must be removed or the pump will not be able to start normally. Such models are not as convenient as self-priming ones; at the same time, they are noticeably cheaper, and with the normal quality of the water supply system, there is practically no significant difference between the two varieties.

The largest difference between the height of the pump and the height of the water level at which the pump can provide normal suction. Without special devices, the maximum value of this parameter is 7-8 m — this is due to the physics of the process. However, when using an ejector (see below), the suction height can be increased several times.

The largest particle size that the pump can handle without problems. This size is the main indicator that determines the purpose of the device (see above); and in general, the larger it is, the more reliable the device, the lower the risk of damage if a foreign object enters the suction line. If the risk of the appearance of too large mechanical impurities is still high, additional protection can be provided with filters or grids at the inlet. However, such a measure should be considered only as a last resort, because from constant exposure to solid particles, the grids become clogged and deformed, which can lead to both clogging of the line and filter breakthrough.

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 construction of various equipment, including pumps. Therefore, when designing parts in direct contact with the liquid, the pH level must be taken into account, and the use of the pump with unsuitable substances is not recommended — this can lead to corrosion, which affects the composition of the pumped liquid and reduces the life of the unit. However, this parameter is critical mainly for specialized models such as pumps for chemical liquids or sewage (see "Suitable for"). In ordinary water (even dirty) the pH range is not so extensive that it cannot be covered entirely.

The presence of an ejector in the design or delivery set of the pump.

The main purpose of the ejector is to increase the effective suction height. Its action is based on the fact that part of the water pumped by the pump is sent back down to the intake point; this water in some way "pushes" the water in the main suction line. Thanks to this, the suction height can be increased from 7-8 m, available without an ejector, to 15-20 m. The main disadvantage of this device is a rather high noise level.

The size of the thread designed to connect the pump to the suction line. This parameter is completely similar to the size of the outlet (see above) — in particular, it can be specified both for the nozzle and for the inlet of the pump.