Max. flow
The maximum flow of a pump is the amount of liquid it can pump in a certain amount of time.
Features of choosing the optimal performance option depend primarily on the purpose of the pump (see above). For example, for DHW recirculation models, the pump performance should not exceed the performance of the water heater. If the water heater is capable of delivering 10 litres per minute to the DHW circuit, then the maximum pump performance will be 10*60=600 L/h. The basic formula for calculating the performance of a heating system takes into account the power of the heater and the temperature difference at the inlet and outlet, and for the cold water system — the number of points of water intake. More detailed information about the calculations for each application can be found in special sources, and it is better to entrust the calculations themselves to professionals.
Minimum operating pressure
The lowest pressure in the circuit where the pump is connected, at which it can perform the main task (see "Suitable for"), providing the claimed operating parameters. The technical features of many modern models are such that some of them can operate at almost zero pressure, simply by the presence of water in the pipe; therefore, this parameter may not be specified at all.
Country of brand origin
In this case, the country of origin refers to the country from which the product brand originates. A brand, in turn, is a general designation by which the products of a particular company are known in the market. The country of its origin does not always coincide with the actual place of production of the product: to reduce the cost of production, many modern companies transfer it to other countries. It is quite normal for products, for example, of an American or German brand, to be made in Taiwan or Turkey. Contrary to popular belief, this in itself does not lead to a decrease in the quality of the goods — it all depends on how carefully the brand owner controls the production. And many companies, especially large and famous ones, monitor the quality very zealously — after all, their reputation depends on it.
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 loud 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 installed in residential premises.
Protection class
It is 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 objects from outside.
The level of protection is usually indicated by a marking of the letters IP ("ingress protection") 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; the 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 — again...st splashes from any direction 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).
In some cases, one of the numbers may be replaced by the letter X — this means that the 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 in itself means a high degree of protection against solid contaminants. At the same time, for such models, an additional letter index can be provided, which describes the degree of protection against specific solid objects — for example, IPX2D. The letter D corresponds to the highest degree of stability, which does not allow the wire to be hit; the previous options A, B and C respectively mean protection from the hand, from the finger and a small tool like a screwdriver.
Insulation class
The heat resistance class of the insulating materials used in the construction of the pump. The higher the heat resistance — the more reliable the device, the less likely it is to ignite or break the insulation in case of overload or overheating. In addition, powerful performant units can become very hot even in normal operations.
In modern pumps, mainly the following classes of insulation are found:
— B. Materials with a heating limit of 130 °C. They are the most modest option by the standards of pumps. Use binding and impregnating compositions of organic origin.
— F. For this class, the heating limit is 155 °C — the average for pumps. Such insulation uses mainly synthetic binders.
— H. Insulating materials based on organosilicon binders/impregnators. Due to this, their heat resistance reaches 180 °C.
