Combustion Blower

 Centrifugal blowers are capable of developing air pressures up to

 2,100 mm H2O. Obviously the higher the pressure or the blower

 capacity, the more expensive the blower. Choosing the most ade

quate blower is important as for the rating the motor needs to satisfy

 the required features (capacity and pressure). The capacity is more

 influent than the pressure.

 Above the pressure limiting value mentioned above piston compres

sors or rotary pumps are necessary.

 A centrifugal blower creates some draft (negative pressure) where

 the blades converge towards the rotating and support shaft. The air

 velocity is slower at the shaft and higher at the impeller or rotor

 edges where blades diverge. The dynamic pressure (function of

 speed) is maximum where the air leaves the blade edges and is con

verted into static pressure in the scroll of the blower.

 The blades of the combustion air blower must be kept clean: fouling

 accumulating on the surface of the blades increases the friction of

 air and consequently decreases the capacity of the blowers. The phe

nomenon may also be controlled by means of checks of the electrical

 load of the engines. In industrial applications and some particular cir

cumstances, we recommend that some proper filtering systems be

 adopted on the air inlets of the blowers.

 In some cases, in order to obtain higher air pressures, blowers in

 series are used. In this application, the air inlet of the downstream

 blower is connected to the pressing mouth of the upstream blower, so

 as to obtain a system where the supplied pressure is equal to the

 sum of the pressures generated by the single blowers.