One stage of a MAPRO® multistage centrifugal blower is generally made of:
- an intake duct conveying the gas to the impeller inlet,
which is coaxial to the shaft;
- a closed impeller with axial flow inlet and radial flow exit;
- a radial diffuser, whose aim is to convert kinetic energy
into static pressure at the impeller exit;
- a discharge volute.
Actually, a centrifugal blower is always used in the multistage configuration. The gas is sucked into the first stage through an inlet volute, every next single stage is linked to the former one through a return channel, and a discharge volute collects the gas from the exit of the last stage delivering it to the outlet pipe. The impellers are built with radial exit blades or backward facing blades. The radial blades allow the achievement of a higher compression ratio, whilst the impellers with backward facing blades, at fixed speed of rotation and for the same differential pressure, produce a characteristic curve with a much wider stable range.
Their main construction features are the following:
- heads, intermediate sections, bearing housings and caps made of cast iron; shaft in carbon steel;
impellers made completely of spark proof aluminium alloy;
- heads and intermediate sections sealed;
- shaft sealing by special double-lip seals.
The blowers are always coupled to the electric motor via belt drives and the safety drive guards
are made of spark-free material. Centrifugal blowers are designed for rotation speeds up to 6000 revolutions/min.The combination of different types of impellers, the possibility of joining several stages in series (up to 10) and the wide range of rotation speeds allow to cover, with the same machine size, a wide range of operation.
Multistage centrifugal air blower and exhausters are also available for
Zone 1 and 2, 21 and 22 of the 2014/34/EU (ATEX)
There are no parts in relative creep during operation. Since there is no friction and therefore no lubrication is necessary, the conveyed air is not polluted. Moreover, the main advantages of using MAPRO® multistage centrifugal blowers are:
- easy installation;
- low noise level;
- no vibration;
- pulsation free gas flow;
- no gas contamination;
- minimal maintenance.
Most common fields of application