The level of protection of the fan housing (more precisely, sensitive parts located in the housing) from dust and moisture, measured by the IP standard. This standard assumes marking in the form of two numbers after the letters IP — for example, IP54. In this case, the first digit describes the level of protection against dust and other objects, and the second — from moisture.
In terms of resistance to the penetration of foreign objects in fans, the following values \u200b\u200bcan be found:
2 — protection against objects larger than 12.5 mm (enough to protect against adult fingers);
3 — from objects larger than 2.5 mm;
4 — from objects more than 1 mm (not every wire can get inside);
5 — full protection against objects; a small amount of dust may have entered the unit without any noticeable effect on performance.
In terms of water protection, options can be as follows:
4 — resistance to water splashes from any direction;
5 — resistance to water jets from any direction;
7 — the ability to endure short-term immersion in water to a depth of 1 m without consequences.
There are also higher rates of water protection. However, it does not make sense to provide them to fans. The mentioned "4" and "5" are quite sufficient for installation in bathrooms, showers and most other places where
...there is a possibility of moisture getting on the units, higher levels of protection complicate and increase the cost of the design, and there is very little practical need for them.
In some models, instead of one digit (most often the first one), there may be the letter X. This does not mean the absence of appropriate protection — it most often exists, and sometimes its degree can be quite high; we are only talking about the fact that official testing according to the IP standard was not carried out. For example, a fan marked IPX4 can be closed even from a thin wire, but if it passed official tests only for moisture resistance, the manufacturer has the right to indicate only one digit.
It is also worth noting that the complete absence of IP marking does not mean a lack of protection. However, if resistance to dust and moisture is crucial for you, you should still choose among models where this feature is officially claimed by the manufacturer.Mounting depth of the fan with a standard installation method.
This parameter describes how deep into the duct the unit (or its parts in the case of surface-mounted models, see "Type") is placed during installation. Knowing the mounting depth, it is possible to assess the suitability of the selected model for a particular installation location: a flat section at the very beginning of the duct must be no less than the installation depth of the selected fan.
The smallest value of this parameter is typical for some overhead models of fans: in them, the main part of the structure is outside, and usually, only 2-3 centimetres are required for installation. And most of all, hidden units require space (see "Type").
