Side channel and TBT blowers (AIR/GAS)

Operating principle

The side channel blower and the TBT increase the pressure of the aspirated gas by the creation, in the peripheral toroidal channel, of a series of vortexes caused by the centrifugal thrust of the impeller. While the impeller is rotating, the vanes force the gas forward and, because of the centrifugal thrust, outwards, producing a helical motion. During this motion, the gas is recompressed repeatedly with a consequent linear pressure increase along the length of the channel.

The rotating TBT and toroidal channel are extremely innovative, born form a long research and trial. The impeller’s wing profile vanes and the central core channel allow this machine to achieve performances close to those of rotating lobe positive-displacement blowers.

Construction features in conformity with the 2014/34/EU Directive (ATEX)

The MAPRO® side channel blowers to be used for extraction or compression of combustible gases, such as biological or natural gas, have been designed in order to fall within the Equipment Group II as required by the 2014/34/EU Directive, Category 2 both for the surrounding area conditions and for the internals of the machines.
Their main construction features are the following:

  • casing and impellers made completely of spark proof aluminium alloy;
  • casing impregnated with Loctite;
  • casing halves sealed;
  • shaft sealing by special double-lip seals which do not require lubrication;
  • two-pole, type of protection “d”, flameproof electric motors, with specific marking Ex II 2 G, additional marking Ex-d IIB T3.

The simplest solution for the manufacturing of the machines is the so-called “CLOSE COUPLED” version – i.e., a flange mounted electric motor is bolted to the blower casing; the impeller, which is dynamically balanced, is fitted directly onto the motor shaft extension. Furthermore, we can offer machines with their own shaft and bearings and coupled to the electric motors via flexible shaft couplings or belt drives. In these cases, the safety drive guards are made of spark-free material.

If the area surrounding the equipment is classified as Zone 2, where, for the Group II, Category 3 equipments are accepted, the machine could be equipped with the type of protection“n” and a non-sparking motor, with specific marking Ex II 3 G, additional marking Ex-nA II T3.

In some particular cases, all the internal aluminium parts wetted by gas can be treated with anodic oxidation; the machine can be supplied with its own shaft and external bearing housings, so that the bearings are completely isolated from the gas handled; and it is also possible to fit lip seals in pairs, with a barrier fluid in between.


The main advantages of using side channel machines are:

  • easy installation;
  • low noise level;
  • no vibration;
  • pulsation free gas flow;
  • minimal maintenance.

Moreover, no internal lubrication is necessary and therefore the gas moving through the machine remains uncontaminated and completely oil-free.

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