Fan power
The highest electrical power consumed by the air curtain when operating in ventilation mode, without air heating.
The performance, speed and range of the airflow depend on this parameter (see below). However, this dependence is not unambiguous — units similar in fan power can differ markedly in other specs. But what this parameter directly affects is energy consumption. For water models (see "Type"), as well as curtains that do
not have a heating function at all (see "Features"), it is the power in fan mode that describes the total electricity consumption. And if an electric heater is provided in the design, then the total energy consumption can be derived by adding the power in fan mode and the maximum heat output (see above).
Airflow
The amount of air that the air curtain can drive through itself in a certain time (usually indicated on an hourly basis).
Performance is one of the main parameters that determine the efficiency of the air curtain. The optimal value of this parameter depends primarily on the size of the door to be blocked. However, when calculating, it is also necessary to take into account several additional issues: the width and general configuration of the door, the presence of a vestibule, etc. Specific recommendations for calculating the required performance can be obtained from special sources or heating engineers.
Max. airflow speed
The highest airflow speed that a air curtain is capable of delivering.
Usually, the speed is measured directly at the outlet because airflow weakens with distance. The practical significance of this parameter is that high speed has a positive effect on performance (see above) and range (see below) because a highspeed air curtain drives a lot of air through itself, and the airflow travels a long distance. At the same time, note that models with the same airflow speed may differ markedly in other performance specs due to differences in design and technology. Therefore, we can say that this parameter is of secondary importance and only complements the range and performance data.
Air temperature increase (ΔT)
This indicator describes the difference between the air inlet temperature and the outlet temperature — in other words, by how many degrees the air temperature rises as it passes through the unit. The higher ΔT, the hotter the outgoing air will be and the more attentively it is necessary to observe safety measures.
Noise level
The highest level of noise generated by the air curtain during normal operation.
The
lower this figure, the more comfortable the use of the unit, the better it is suitable for cases where noise is undesirable. When choosing according to specific values recorded in the characteristics, it should be taken into account that the decibel used to measure the noise level is not a linear quantity: for example, an increase in sound power by 2 times corresponds to an increase of 3 dB, 10 times — by 10 dB, 100 times — by 20 dB. Therefore, to assess the noise level, it is easiest to refer to comparative tables, where the correspondence of specific values in decibels to various real sound sources is recorded. In most modern air curtains, the noise ranges from 25 to 70 dB, here is the simplest table for this range:
20 – 25 dB — a weak audible sound, comparable to a whisper at a distance of 1 – 2 m;
25 – 30 dB — intelligible whisper at a short distance, ticking of a wall clock;
35 dB — muffled conversation;
40 – 45 dB — normal human speech;
50 – 55 dB — talking in raised tones, noise in the office;
60 dB — loud conversation at a distance of 4 – 5 m.
70 dB — loud conversation nearby.
Dimensions (WxHxD)
General dimensions of the over-door heaters. The amount of space occupied by the unit during installation depends on the dimensions, but also the dimensions of the space it covers — namely the width of the airflow (or height, if the flow is directed not down, but to the side). Most air curtains have characteristic elongated proportions, and the mentioned width/height corresponds to the largest dimension of the device.
Note that the width and height of the air curtain, in this case, are indicated for the standard installation method (see above): for example, devices installed on top will have a large width at a low height, and side ones vice versa. For models with universal mounting, the dimensions can be indicated in different ways, but it is usually not difficult to evaluate the characteristics of the flow in them if we take into account the elongated proportions described above — the largest dimension is usually the same as the width/height of the flow.
Features of choosing an air curtain in terms of dimensions (and, accordingly, the width of the covered space) also depend on the type of its installation. When mounted above the doorway, the width of the unit must be no less than the width of the doorway (and ideally, a little more, with some margin). If the curtain is installed on the side, it is enough that its height is 3/4 of the height of the opening — due to the peculiarities of the movement of heated air, this will completely cover the required space.
