The Science Behind Vacuums

Knowing how practical I am about teaching science, one day a student asked about vacuum cleaners and why the new technology is so important. He brought up the subject because his mother wants a new machine, specifically the cyclone Dyson, when the old one is working perfectly well. I can see his father balking at the expense and was eager to support the child who was trying to back his mother in her request. I wanted to explain in layman’s terms how suction power varies with different brands.

Traditional vacuums are ingenious but less innovative than the Dyson model. It is all about air pressure not an actual “vacuum”. Suction is the mechanism that picks up dirt. With a piece of tissue paper and a comb, any mysteries will be revealed. Starting my demonstration, I breathe out as much as I can.  The teacher that I am wants to explain the process in simple terms, and I hold my breath while placing the two items (the tissue wrapped around the comb) against my mouth. I lean against a dusty upholstered chair and press my mouth and the comb against the piece of furniture. When I take in a sharp breath, I am breathing through the comb. Taking the item away from my mouth, I see that the tissue is full of dirt! Basic science in a nutshell.  Repeating these steps, I see that the tissue builds up debris and the air isn’t flowing quite sufficiently. Thus, a suction vacuum has to have powerful air flow. It has to have a decent motor and good filter system, bagless or not.

The dual cyclone Dyson still operates as a suction appliance, but with an upgrade such that the dirty air is drawn in by a fan. There is a drum in the vacuum bin whose top corner takes in this air—the angle is most important in the technology since it creates a centrifugal force (a spiraling motion). The largest dust particles spin out of the airstream, falling to the bottom of the drum. Interesting but not complicated. The filter then traps the air, catching more particles, as the air continues its path along a cone-shaped cylinder, also found in the bin.  The air spins to the cone’s bottom, faster and faster, as the centrifugal force increases. Ultimately, dust is forced against the cone sides and through a hole as air escapes up the center. This was a revolution in vacuum machine science that only came in the 1970s, later upgraded to the Dyson Ball in 2005.

Bravo to James Dyson for giving us an energy-saving and time-efficient alternative to traditional suction.  Before his inventions, talking about vacuum cleaners was never as interesting. Meanwhile, my student has an arsenal of information with which to convince his dad that the time has come for a new vacuum for mom. How appropriate that it is Mother’s Day.