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.
Max. pressure
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.
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.
Ejector
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.
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.
Noise level
The noise level produced by the pump during normal operation. For comparison, 50 decibels roughly corresponds to the noise in an office room, 60 dB to an average TV volume, 70 dB to a truck at a distance of about 8 m, 80 dB to traffic noise, and 90 dB to a scream. The lower the noise level, the more comfortable the use of the pump and the closer it can be placed to people. This parameter is especially important for models designed for indoor installation.
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.
Impeller / auger material
The material from which the main working element of the pump is made is an impeller, an auger or a membrane. This part is in direct contact with the pumped liquid, so its specs are key to the overall performance and capabilities of the pump.
— Plastic. Plastic is low-cost, and it is not subject to corrosion. It is believed that the mechanical strength of this material is generally low, and it does not tolerate contact with solid impurities. However, today there are many varieties of plastic — including special high-strength varieties that are suitable even for working with heavily polluted water or sewage. So plastic impellers/augers can be found in a variety of types of pumps; the overall quality and reliability of such parts, usually, depend on the price category of the unit.
— Cast iron. Solid, durable, reliable and, at the same time, relatively inexpensive material. In terms of corrosion resistance, cast iron is theoretically inferior to more advanced alloys like stainless steel or aluminium; however, subject to the operating rules, this point is not critical, and the service life of cast iron parts is no less than the total service life of the pump. The unequivocal disadvantages of this option include a large mass, which slightly increases the energy/fuel consumption during operation.
— Stainless steel. By the name, one of the key advantages of stainless steel is high resistance to corrosion — and, accordingly, reliability and durabili...ty. Such an alloy is somewhat more expensive than cast iron, but it also weighs less.
— Aluminium. Aluminium alloys combine strength, reliability, corrosion resistance and low weight. However, such materials are quite expensive — more expensive than the same stainless steel, not to mention cast iron.
— Brass. The varieties of brass used in pumps are distinguished by high strength and hardness, as well as insensitivity to moisture. Such materials are quite expensive, but this price is fully justified by the mentioned advantages. Therefore, in certain types of pumps — in particular, surface models and pressure tank units — brass impellers are very popular.
— Bronze. A material similar in many properties to the brass described above. However, bronze is used much less frequently — in particular, due to a slightly higher cost.
— Steel. Varieties of steel that are not related to stainless steel are used extremely rarely — in certain models of pumps for chemical liquids. At the same time, steel is usually used as a base in such parts, and a coating of fluoroplastic or other similar material is applied to it to protect it from corrosion.
— Silumin. Silumins are called aluminium alloys with the addition of silicon. For several reasons, such materials are rare in pumps, and mainly among relatively inexpensive models.
— Rubber. Material traditionally used for diaphragms in vibratory pumps (see “Pump type”).
