Blowers, and Fluidizers

Technically, fans and blowers are two separate types of devices that have a similar function. However, the terms are often used interchangeably to mean any device that delivers a quantity of air or gas at a desired pressure. Differences between these two devices are their rotating elements and their discharge-pressure capabilities. Fluidi2ers are identical to single-stage, screw-type compressors or blowers. 

The type of rotating element or wheel that is used to move the air or gas can classify centrifugal fans. The major classifications are propeller and axial. Axial fans also can be further differentiated by the blade configurations. 

This type of fan has a limited ability to boost pressure. Its use should be limited to applications where the total resistance to flow is less than 

Axial fens are essentially propeller fens that are enclosed within a cylindrical housing or shroud. They can be mounted inside ductwork or a vessel housing to inject or exhaust air or gas. 

This type of fan should not be used in corrosive or explosive environments, since the motor and bearings cannot be protected. Applications where concentrations of airborne abrasives are present should also be avoided. 

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Tables 13-3 and 13-4 (below) list the common failure modes for fans, blowers, and fluidizers. Typical problems with these devices include (1) output below rating, (2) vibration and noise, and (3) overloaded driver bearings.

Blowers, or positive-displacement fans, have the same common failure modes as rotary pumps and compressors. Table 13.4 lists the failure modes that most often affect blowers and fluidizers. In particular, blower failures occur due to process instability, caused by start/stop operation and demand variations, and mechanical failures due to close tolerances. 

Table 13.4 Common failure modes of blowers and fluidizers...

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