Central Vacuum Systems And Wet/Dry Vacuums
The first electric vacuum cleaners showed up in the early 1900s, and were an immediate success (though for many decades they were sold only as a luxury item).
One very popular vacuum-cleaner design from this era is finding resurgence in popularity today. This design, the central vacuum system, turns your whole house into a cleaner. A motorized fan in the basement or outside the house creates suction through a series of interconnected pipes in the walls. To use the cleaner, you turn on the fan motor and attach a hose to any of the various pipe outlets throughout the house. The dirt is sucked into the pipes and deposited in a large canister, which you empty only a few times a year. For more information, see How Central Vacuum System Work.
For heavy-duty cleaning jobs, a lot of people use wet/dry vacuum cleaners, models that can pick up liquids as well as solids. Liquid material would soak paper or cloth filters, so these cleaners need a different sort of collection system.
The basic design is simple: On its way through the cleaner, the air stream passes through a wider area, which is positioned over a bucket. When it reaches this larger area, the air stream slows down, for the same reason that the air speeds up when flowing through a narrow attachment. This drop in speed effectively loosens the air's grip, so the liquid droplets and heavier dirt particles can fall out of the air stream and into the bucket. After you're done vacuuming, you simply dump out whatever has collected in this bucket.