Maximum head
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.
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.
Maximum particle size
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.
Maximum liquid temperature
The highest temperature of water at which the pump is capable of operating normally. Usually, in most models this parameter is 35-40 °C — at high temperatures it is difficult to ensure effective cooling of the engine and moving parts, and in fact, such conditions are rare.
Float switch
The presence of a float switch in the design of the unit.
The operation of such a switch is based on a sensor in the form of a float, which determines the level of the pumped liquid. At the same time, such a sensor can perform several functions at once. The main one is the protection of the pump from dry running: when the liquid level drops critically, the sensor turns off the pump, preventing air from entering the line and helping to save energy. In addition, the float can be used as an overflow sensor (warning of a critical increase in the liquid level), and in some models also as a general-level sensor (reporting the actual amount of liquid).
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.
Protection class (IP)
An indicator that determines the degree of protection of dangerous (moving and current-carrying) parts of the hardware of the pump from adverse effects, namely solid objects and water. Since pumps, by definition, are used for pumping liquids, and many of them can normally pass quite large particles, in this case, we are talking about protection against moisture and foreign objects from outside.
The level of protection is usually indicated by a marking of the letters IP and two numbers, the first of which indicates protection against the effects of solid objects, and the second — against the ingress of water.
For the first digit, each value corresponds to the following protection values: 1 — protection against objects with a diameter of more than 50 mm (large body surfaces) 2 — against objects with a diameter of more than 12.5 mm (fingers, etc.) 3 — against objects more than 2.5 mm (most tools) 4 — against objects larger than 1 mm (virtually all tools, most wires) 5 — dust-proof (total protection against contact; dust can enter, but does not affect the operation of the device) 6 — dust-proof (case with full dust protection and contact).
For the second digit: 1 — protection against vertically falling drops of water 2 — against drops of water with a deviation of up to 15° from the vertical axis of the device 3 — against drops of water with a deviation of up to 60° from the vertical axis of the device (rain) 4 — against splashes from any direct...ion 5 — from jets from any direction 6 — from sea waves or strong water jets 7 — short-term immersion to a depth of up to 1 m (without the possibility of continuous operation in immersed mode) 8 — long-term immersion to a depth of more than 1 m (with the possibility of permanent operation) in immersed mode).
Note that in some cases one of the numbers can be replaced by the letter X — this means that official certification for the corresponding parameter has not been carried out. In pumps, X is usually put in place of the first digit, because. a high degree of moisture resistance (and for submersible models, for example, it must, by definition, correspond to 8) means a high degree of protection against solid contaminants.
Country of origin
Country of origin of the brand under which the pump is marketed.
There are many stereotypes related to how the origin of goods from a particular country affects their quality. However, these stereotypes are unfounded. Firstly, this paragraph does not indicate the actual place of production of the unit, but the "homeland" of the trademark (or the location of the manufacturer's headquarters); production facilities may be located in another country. Secondly, the actual quality of the product depends not so much on geography, but on the organization of processes within a particular company. So when choosing, it is best to focus not so much on the "nationality" of the pump, but on the overall reputation of a particular brand. And paying attention to the country of origin makes sense if you fundamentally want (or do not want) to support a manufacturer from a certain state.
