1. TECHNOLOGICAL ROLE
Fans are designed to increase the static pressure of a volumetric fluid flow per second Vs by a required value Δp, and eventually accelerate it at high speeds.

2. TRANSPORTED FLUID
Steel fans are pneumatic transporters, propelling air and gas either clean or laden with particles of various substances.
Fluid temperature must typically be lower than 90 °C, but can even reach 350 °C in suitable circumstances.

3. OPERATING RANGE
Steel fans can generate flows of up to 350,000 m3/h, at pressures of up to 50,000 Pa.

4. EQUIPMENT AND PROCESS DESCRIPTION
Each fan consists of a casing and an interior turbine driven by an electric motor.
Steel fans are classified according to several features:
– according to propeller orientation relative to liquid flow direction: radial (centrifugal), axial, and diagonal.
– according to maximum achievable air pressure: low (below 100 mmH2O), medium (between100 and 300 mmH2O), and high and very high pressure (over 300 mmH2O);
– according to designated use: general and special use (in explosive, toxic, abrasive, corrosive, pneumatic and other special types of environment).
– according to construction model: with rotor mounted directly on motor shaft, connected to it via elastic coupling, or connected by means of a reducer (usually belt drives); single and multi-level.
– according to level of noise generated: silent and non-silent.
All specified characteristics indicate fan capabilities when operating at air temperature 15ºC, pressure 760 mmH2O (sea level atmospheric pressure), and therefore in an atmosphere of specific mass, γ = 1.226 kg/m3.