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Fan rules

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Fan sizes

 

  • Efficiency
 Q [m3/h], [m3/s]
  • Total pressure
 Δptot = Δpst + Δpd [Pa]
  • Static pressure
 Δpst = Δptot – Δpd [Pa]
  • Dynamic pressure
 Δpd = ρ/2 * c2 [Pa]
  • Density
 ρ [kg/m3]
  • Temperature
 T [°C], [K]
  • Speed
 N [1/min]
  • Power consumption on the fan shaft
 Nw [W], [kW]
  • Engine power consumption
 N [W], [kW]

Fan rights

Flow data is presented in graphs – characteristics of fans. The graphs directly refer to model fans that have been designed and tested in a normative measurement channel. The company, as a decisive leader among fan manufacturers, has extensive knowledge in the field of fan selection and regulation. In the case of complex installations with different possible regulations, the customer is informed of all the possibilities.

1. Speed control

The fan motor controlled by a frequency inverter has different rotational speeds.

Below are the characteristics with a visible change in individual fan parameters depending on the rotational speed. The graph shows the change in efficiency, pressure, power, efficiency and sound power.

The volume of air changes in direct proportion to the fan speed:

The static pressure varies in the square of fan rotation:

The power of the fan varies in the third power of rotational speed:

In contrast, the sound power varies on a logarithmic scale, i.e. 50 decimal logarithms in relation to the rotational speed:

2. Adjustment by changing the diameter

It is also possible to increase or decrease the diameter of the fan in the installation. The flow parameters and power will then change as follows:

Successively, the sound power varies according to the following dependencies:

3. Density change

In most cases, the air density is ρ=1.15 [kg/m³](at sea level and at 20°C). The density depends on the temperature, pressure, humidity of the medium and altitude above sea level.As an engineering company, we scrupulously approach the subject of selection and analyze the entire work cycle. We take into account the conditions prevailing at the time of fan start-up, key operating moments, the influence of the environment and the parameters of the medium. In this way, we optimize the operation of each of our fans.

The sound power remains constant when the density changes:

 

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