Pump type
The basic principle 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), have a large suction height (see below), and the fluid flow is continuous. At the same time, the performance of such units can drop dramatically with high resistance in the water supply system. In addition, if the liquid level is below the inlet, the pump will have to be refilled with water before each start.
— Vortex. Peripheral 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 centrifugal ones in terms of pressure; in addition, they are usually self-priming (see "Suction...type"), and the design in most cases is such that the pump has to be filled with water only when it is first turned on after installation. On the other hand, such models are sensitive to contamination — even small particles entering the impeller can cause damage, significantly reducing efficiency. Yes, and the efficiency of vortex pumps is low — 2-3 times lower than that of centrifugal pumps; they are also inferior in suction height (see below).
— Centrifugal-vortex. Pumps that combine the two principles described above in operation. Such a unit is a pair of centrifugal and vortex pumps mounted on a common shaft and connected in series. During operation, water first enters the centrifugal wheel, which is responsible for suction, and then to the vortex wheel, which provides pressure. Due to this, it was possible to combine the advantages of both types in one unit — a large suction height, a high pressure and a self-priming device. However, these units cost accordingly.
— Vibratory. The term "membrane" is also used. The action of vibration pumps is based on the use of a flexible membrane, equipped with a device that makes it vibrate. This membrane is one of the walls of the working chamber, and the chamber itself has inlet and outlet valves. When the membrane moves "out" and the volume of the working chamber increases, the inlet valve opens (the outlet is closed), allowing fluid to enter; and when the membrane moves “inward” and pushes the liquid out, on the contrary, the outlet opens. The main advantages of this device are simplicity, compactness, versatility, low cost, ease of regulation and almost complete insensitivity to dry operation. At the same time, the service life of such units is relatively short due to the strong wear of the membrane.
— Auger. The main part of such pumps is precisely the auger — a rotor (or several rotors) in the form of a screw. This design makes the pump very reliable, allows it to achieve high outlet pressure and uniform liquid supply, provides self-priming (see "Suction type"), and also has a low noise level. At the same time, auger units are difficult to manufacture and, accordingly, expensive.
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.
Dry run protection
A system that protects the unit from running without water.
The dry running mode is abnormal for any pump: at best, the mechanism of the unit in this mode experiences increased loads, and at worst, the device may fail and even a serious accident. This feature allows you to prevent such consequences. The specific method of protection against dry running may be different; one of the most popular options is a float switch (see below). However, in addition, flow sensors, pressure or level switches can be used. These details depend both on the general type of pump and on the specific model; they should be specified separately in each case.
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).
