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Cleaning Nozzle Design Considerations

When it comes to cleaning performance, there is a tendency to look primarily at the power of the suction motor and the amount of bristles on the brush roll. While these are important considerations, the design of the cleaning nozzle can have a significant effect as well. It is the force exerted by the air flow combined with agitation, that actually picks up the dirt at the cleaning nozzle. This article explores some nozzle designs which will improve the actual cleaning performance of many vacuum cleaners.

Nozzle Designs Affecting the Air Flow Velocity

The velocity of the air flow in the nozzle is affected by the nozzle design as well as the amount of air flowing through the entire vacuum cleaner system. Our article on Air Flow Through the System discusses additional factors which affect the air flow and how they relate to actual cleaning performance.

The higher the velocity of the air flow close to the surface being cleaned, the better the cleaning performance will be. The smaller the area through which the air flow is passing, the greater will be velocity will be. For this reason most nozzles, especially carpet nozzles without revolving brush rolls, have fairly narrow openings across their full width. To clean below the carpet's surface they must cause the air to flow through the carpet fibers with sufficient velocity to force the dirt to move with it. To remove dirt and grit embedded deep within a carpet is virtually impossible using air flow alone so uprights and power nozzles with revolving brush rolls were developed. Their effect is discussed further in our article on the Effects of Brushing Action.

Many floor brush attachments are designed with a row of bristles around their perimeter with the bristles along the front being shorter to allow a space for the dirt to enter. Another floor brush design has a single brush strip which is centered front to back plus some short rows of bristles on the front and rear edge near the center to keep it fairly level. Both designs work well as long as they keep the air flow as close to the floor surface as possible. This typically is done on floor brushes with the perimeter bristles by having a short wall along the inside edge of the bristles so the gap between it and the floor is sufficiently small. This wall also prevents bristles from being pulled inward by the air flow moving through them. The bristle lengths of the center mounted strip are relatively short so the gap between the floor and attachment body is also sufficiently small.

The air flow velocity should be similar across the full width of the nozzle so all areas are cleaned well. Most cleaning attachments have funnel shaped air passages which lead to centered hose or wand connectors. This allows the air to uniformly flow from all locations across the nozzle. As discussed below, some uprights and power nozzles have similar designs as well. Unfortunately, many uprights with on-board attachments have brush roll housings with the air inlets very close to one of their sides so the air flow velocity is significantly greater on that side compared to the opposite side. Also, many roll housing rear walls on these uprights are straight rather than funnel shaped, increasing that undesired effect even more. All power nozzles have air inlets near the center of the nozzle but those with straight rear walls will experience less air flow velocity closer to the nozzle edges although not to the degree which uprights with non-centered inlets experience.

High Performing Upright & Power Nozzle Designs

As mentioned above, the nozzle should also be designed so it produces similar air flow velocity across its complete width, not just near the air passage leading from it. Some uprights and power nozzles incorporate a center mounted air intake behind or above the brush roll which flares out to the edges of the cleaning nozzle as it approaches the brush roll. This wide funnel shaped opening causes the air flow to be distributed quite evenly across the entire cleaning width for more efficient and uniform cleaning. This also creates a dirt collection area immediately behind or above the brush roll so most of the dirt and grit is gathered by the brushes and whisk away by the air flow before it can bounce back out of the nozzle. This substantially reduces the scatter effect which many uprights and power nozzles experience when picking up grit and small stones.

Examples of uprights which use this design are the Lindhaus upright, Commercial Eureka uprights, Commercial and Heavy Duty Sanitaire uprights by Electrolux Home Care Products North America (formerly The Eureka Company) and Kirby uprights. All of these are high performing uprights, most of which are traditional uprights which combine this design with large diameter fans for outstanding carpet cleaning performance. Examples of power nozzles which use a similar design are those made by Lindhaus and Panasonic.

Upholstery Nozzle Design

Most vacuum cleaners include a small nozzle about 4" to 6" wide with a fairly narrow opening about 1/4" to 3/4" deep. This nozzle, often called the upholstery tool, is designed for cleaning upholstered furniture, window curtains and carpeted stairs. The air inlet is designed in a funnel shape so air flow if distributed quite evenly across the entire cleaning width. Since the air flow is restricted to a much smaller area than the larger carpet nozzle, when all else fails due to poor vacuum cleaner performance, it is used by some for cleaning carpet as well.

To loosen dirt and help pick up pet hair and threads, many upholstery nozzles have a straight brush strip mounted just behind the opening. Some companies have developed motor or turbine driven revolving or rotating brushes which provide agitation for more effective cleaning. Examples of upholstery nozzles with motor driven revolving brush rolls are those included with some deluxe Kenmore, Panasonic and Aerus (formerly Electrolux) power teams. The motors in these nozzles actually adds power to the system whereas those driven by turbines draw their power from the air flow. Turbine driven upholstery nozzles with rotating brushes are included with many Hoover uprights and SteamVacs as well as the Kirby uprights. Available for use on most vacuum cleaners are upholstery nozzles with turbine driven revolving brush rolls like the Miele STB 101 Turbobrush and generic 0905C and 120 Air Turbine Upholstery Nozzles. Whether motor driven or turbine driven, these powered brushes can make a significant difference in the effectiveness of their upholstery nozzles.

Summary

Sufficient force from the air flow velocity as well as agitation from revolving or rotating brushes can make a huge difference in the cleaning performance of a vacuum cleaner, especially on carpet and upholstery. Both high performing uprights and canisters with power nozzles (power teams) are available to match your cleaning style and preference. Typically, both will clean very well although some better than others due to their nozzle designs as well as other system designs.

A few companies like Electrolux Home Care Products North America (formerly The Eureka Company) (Commercial & Sanitaire) and Kirby still make the traditional upright designs with the funnel shaped nozzle housings. These are very durable uprights which have outstanding performance when it comes to cleaning carpeted floors. If high filtration is needed though, look more to very durable and high performing "clean-air" uprights with Certified HEPA filtration and sealed systems like the Miele and Lindhaus two-motor uprights.

Next Vacuum Performance Aspect: Effects of Vacuum Cleaner Brushing Action

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