The number of zeros indicated on the body of the vacuum cleaner can turn the head of an inexperienced user, but it does not fully characterize the device’s ability to draw in dust. Of greater interest in the characteristics of vacuum cleaners is the suction power. We will talk about it in the material.
Determination of the suction power
In general terms, power is a quantity that characterizes the rate of energy transfer (work performance) per unit of time. In mechanics, electrical engineering, thermodynamics, etc., there are definitions of power, but this does not change the general principle of a physical quantity. For example, in mechanics, power refers to the work done per unit of time, in electrical engineering – energy expended or received during the same unit of time.
With regard to vacuum systems, and vacuum cleaners refer specifically to them, there is the concept of suction power, that is, the ability of a vacuum cleaner to draw in a certain volume of air for a certain time. According to the principle of operation of the vacuum cleaner, in order to create a flow that rushes into the body, it is necessary to create a vacuum inside (low pressure zone). The higher the vacuum, the more actively air and dust will rush there.
There are other units of measure for “air power” called aerowatts. In fact, this is the same physical unit, but for simplicity of perception it was named a little differently. Since aerowatts are not included in the list of physical units included in the international system of SI units, it would be technically more correct to measure power in conventional watts.
The difference between suction power and electrical power
As you can see from the definition given above, the suction power characterizes the operation of the vacuum system of the vacuum cleaner. While electric power is understood as the energy spent on the operation of the electric motor of the vacuum cleaner.
vacuum generated inside the housing;
diameter and, as a consequence, the size of the section of the vacuum cleaner hose;
the presence of obstructions in the path of the air flow, etc.
As a rule, the value of the suction power for household vacuum cleaners is in the range of 150-400 watts. The higher this indicator, the better the device sucks up debris and dust.
Suction power measurement method
The method of determining the suction power involves measuring the amount of air flow and vacuum created in a vacuum system. One of the variants of the measuring stand is shown in the diagram.
The air flow is calculated by multiplying the air speed (anemometer reading) by the cross-section of the line connected to the device. The vacuum is measured with a vacuum gauge, or, as shown in the diagram, a differential pressure gauge. Its use is more preferable, since the device has two sensors for measuring (vacuum and overpressure). The overpressure sensor is not connected to the system. It measures atmospheric pressure, and its readings are used to calculate the difference between normal pressure and the pressure in a vacuum system. The difference between the readings of the sensors is nothing more than the value of the vacuum created inside the housing.
The product of the measured flow and vacuum gives the suction power.
It is important to understand here that any obstacle in the path of the air flow (garbage bag, filter system, etc.) reduces the air flow rate and, as a result, negatively affects the value of the suction power, significantly reducing it. Also, parasitic air leakage caused by malfunctions of the vacuum cleaner (cracks in the hose, housing, loosely closed covers, etc.) is unacceptable, since the intake of air from the outside reduces the value of the useful flow.
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There is no single standard according to which suction power is determined. It is currently under development. Therefore, vacuum cleaner manufacturers measure power in their testing laboratories, guided by internal regulations and procedures. Moreover, the values of the suction power of a particular model do not always become public knowledge. There are no rules for specifying it.
The presence of this parameter in the technical passport of the vacuum cleaner is a sign of good form and respect for the consumer.