Maximum performance
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.
Maximum immersion depth
The maximum depth at which a submersible pump can be placed without the risk of failure or breakdown. It is usually indicated for fresh water, so in fact it is advisable not to lower the pump to the maximum depth level — after all, the density of the pumped liquid may be greater, which will create off-design loads on the structure.
Grinder
A device for grinding large mechanical impurities contained in the pumped liquid.
The grinder is installed at the pump inlet, in front of the main mechanism. Its task is to protect this mechanism from jamming and/or damage: the grinder crushes the impurities contained in the water into small particles, which the pump itself can handle without any problems.
This function is most relevant when working with heavily contaminated liquids; so most units with grinders are designed for dirty water or sewerage (see “Suitable for”). At the same time, a similar function can also be found in models for clean water — it increases overall reliability and provides an additional guarantee in case large particles do end up in the water.
Maximum power
Rated power of the pump motor. The more powerful the engine, the higher the performance of the unit, usually, the greater the pressure, suction height, etc. Of course, these parameters largely depend on other features (primarily the pump type, see above); but models similar in design can be compared in terms of power.
Note that high power, usually, increases the size, weight and cost of the pump, and also implies high costs of electricity or fuel (see "Power source"). Therefore, it is worth choosing a pump according to this parameter taking into account the specific situation; more detailed recommendations can be found in special sources.
