Just as with the blades in the fan assembly creating turbulence, frontal attachments on a machine also generate turbulence, as does the hose and any connectors.  Each time there is something placed in the path of the airflow there will be turbulence.  The problem of turbulence is that it works against airflow.  When airflow is reduced so is it’s capacity for carrying contaminants.  Reduction in contaminant carrying ability translates to poor performance overall.

When air flows past a bump, air pressure will increase as it is compressing over the bump, and then decrease as it comes back in touch with the rest of the air (primary airflow).  The changing air pressures cause airflow to become uneven causing the primary flow of air to slow down.  The more turbulence that is introduced the slower the primary airflow becomes.

Turbulence is generated by bumps and any other obstruction in the airflow.  Turbulence can also be caused by flexible hoses.  Since air has mass it also has inertia.  When a path of air is changed, as with a flexible hose, the air particles collide with side walls and create turbulence.  Each time the hose is moved or bent the airflow is impeded.

To overcome the turbulence in a hose, manufacturers increase the power plant’s ability to create a vacuum and thus generate more powerful airflow which fights against the impeding effects of turbulence.

Design of airflow plays an important part in machine effectiveness.  In a torpedo styled vacuum cleaning machine there is a wand, a hose, and a power plant/contaminant collection system.  Electrolux was famous for their torpedo machines.  The difficulty this machine faced was one of airflow and collection.

The airflow was elongated 12-15 feet in front of the power plant.  To remove mild surface contaminants Electrolux designed a “power head” to shake the carpet being cleaned to loosen and launch surface dirt into the airflow and back to the collection bag.  Along the way the airflow encountered several turbulence areas which reduced airflow.  The power plant was situated in the contaminant airflow before the collection point.  Needless to say the motors burned out often in this design from overheating due to a blanket of contaminants surrounding the motor increasing the operating temperature.

Just as there is turbulence impeding airflow leading up to the power plant, there is turbulence past the power plant that equally impacts vacuum cleaning machines.  There are many factors that contribute to poor performance of a machine, but the most significant is the dust collection design.

The air path past the power plant can vary from manufacturer to manufacturer.  Hoses, pipes, and canisters all are used to channel the particulate-laden air to a collection point.  Depending on the style of the machine there may only one or all three methods employed.  Generally, the less turns and connectors present the better for airflow.

Collection bin design also affects machine efficiency.  Large surface areas for escape air are desirable in every situation.  Review the dust bin discussion for more detail.

Overcoming turbulence is not as difficult as it sounds.  In fact, the upright design of Hoover and Kirby removed the need for a hose or wand altogether.  The power plants in these machines are directly coupled with the agitation head within a few inches.  This eliminates completely the turbulence and any impeding of the airflow.

Other uprights handle the air pathway by sending the air past the agitation head to a tube or hose which introduces turbulence and impedes airflow.  Some manufacturers use smooth rigid tubing and short lead-in air paths to reduce airflow impedance.  In either case manufacturers that reduce turbulence can enjoy a design with a smaller power plant which equates to less fatigue in operating machines.

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