Filters
Types of filters provided in the device with the purifier function (see "Type"). Some models allow you to install additional filters that are not provided in the standard configuration; however, for a full guarantee, it is better to immediately buy a device with the necessary equipment. Here are the most popular types of filters nowadays:
— Pre-filter. The filter installed first at the inlet to the device. Usually provides the simplest mechanical filtration from relatively large contaminants, for which it makes no sense to use more advanced and expensive solutions like HEPA or NANO elements (see below). And some devices are not equipped with any other filters at all, except for the pre-filter.
— Electrostatic filter. The action of such a filter is based on the property of the smallest particles in the air to acquire an electric charge and be attracted to an oppositely charged object. It provides effective cleaning from dust, smoke and soot; in addition, the air is also slightly ionized, which can also be attributed to the advantages (for more information about ionization, see "Features"). But with odours and harmful volatile substances, such a filter handles poorly. The design of an electrostatic filter is based on a set of metal plates that are charged; the plates need to be regularly cleaned of dirt, they do not require other maintenance, so the filter life is almost unlimited.
— HEPA filter. Dry fine filter. It is similar in design to co...nventional mechanical filters, but differs from them in terms of the principle of operation: dirt particles do not so much get stuck between the filter fibres as they stick to them. As a result, HEPA filters can retain contaminants that are much smaller than the gaps between the fibres, which ensures high filtration efficiency. Different types differ in quality. So HEPA 10 can capture at least 85%, HEPA 11 — 95%, HEPA 12 — 99.5%, HEPA 13 — 99.95% and HEPA 14 — 99.995%.
— NANO filter. Porous ultrafine filter. Detains particles with a size of thousandths of a micron (millionths of a millimetre), cutting off not only small mechanical impurities but also individual molecules of organic substances (although such a filter is still inferior to a charcoal one in terms of molecular purification efficiency).
— Charcoal filter. Filter based on activated carbon or other similar adsorbent. It can effectively retain volatile molecules of various substances, thanks to which it perfectly eliminates odours. On the other hand, the charcoal filter is demanding compliance with the service life: after the resource is exhausted, it not only loses efficiency but also becomes a source of harmful substances, so in such devices it is especially important to change the filter elements on time.
— Photocatalyst. The principle of operation of such a filter is to decompose the harmful substances that enter it into neutral components (mainly water and carbon dioxide) under the action of ultraviolet radiation and a special catalyst. It is not designed to remove mechanical impurities, but it does an excellent job of removing odours and harmful volatile impurities, and also effectively destroys bacteria and viruses. At the same time, the catalyst is not consumed during operation, and the reaction products evaporate on their own — so that the filter has an almost unlimited service life, while it practically does not require maintenance. The main disadvantage of photocatalysts is their high price.
— Antibacterial. Under this name, several types of filters are combined, designed primarily for the destruction of harmful microorganisms. So, some antibacterial filters use an active substance that destroys the protein shell of microbes, others use an ionizer or ozonizer, others use UV radiation, etc. So the specific features of such a filter and the rules for its maintenance should be clarified separately.
– Ultraviolet lamp. A lamp that processes passing air with UV radiation. This treatment provides a bactericidal effect: ultraviolet light neutralizes most bacteria, viruses and fungi.
In addition to those described above, modern cleaners may include other, more specific types of filters — for example, to neutralize formaldehyde or ozone, which can be useful in some types of industries.
Operating time
It is the operating time of the humidifier with a full tank. It depends on the volume of the tank and on the water consumption (see below for both). For models with humidity control (see "Features"), this parameter can be indicated in different ways: in some cases, the maximum duration of the operation is given (at the minimum output humidity), and in others — vice versa. Nevertheless, according to the declared figures, it is quite possible to estimate the operating time at least approximately.
Water tank volume
The volume of the water tank installed in the humidifier. Large capacity allows you to work longer without refuelling but affects the dimensions and weight of the device. Therefore, manufacturers choose the volume based on a compromise between these points and taking into account water consumption. Usually, the volume of the tank is chosen in such a way that the humidifier can work quietly on a single refill for at least 2-3 hours, and often even more. Accordingly, the more capacious the tank, the more powerful and performant the device, as a rule. So, models with a volume
of up to 2 litres belong to the entry-level,
from 2 to 4 litres — to the average,
from 4 to 6 litres — to the larger than average category, and in the most capacious devices this figure can
exceed 6 litres .
Note that for models with the possibility of using a bottle (see below), this paragraph often indicates the optimal capacity of the bottle (such devices may not have their tanks).
Maximum noise level
The noise level generated by the air purifier during operation. Most of these devices are used in residential areas, so this parameter should be treated carefully. According to sanitary standards, constant noise in such rooms should not exceed 40 dB (quiet conversation) during the day and 30 dB (wall clock ticking) at night. More detailed comparison tables and recommendations can be found in special sources. It is also worth mentioning that the noise level is indicated for the maximum operating speed, so the noise level will be significantly lower in reduced mode.
Power consumption
It is the maximum power consumed by the device during operation. The lower it is the more economical the device. However, it is worth noting that in humidifiers, energy consumption is directly related to the principle of operation (see "Humidiation"): with similar characteristics, steam models are high consumption, where energy is spent on heating water, and the most economical are water models. Nevertheless, the energy consumption of modern humidifiers is generally low — even for steam humidifiers it rarely exceeds 600 W, and ultrasonic devices with similar power are already heavy industrial equipment. Purifiers also do not differ in consumption: a power of more than 100 W is rare among such devices.
