Friday, June 21, 2013

Vacuum Cleaner Suction Revisited

A few months ago I wrote about how to calculate the suction of a vacuum cleaner. The article was prompted by something I read in Wikipedia about how typical vacuum cleaners would generate up to 20 kPa of suction. This seemed like an outrageous amount, and so I wrote an article showing that it should only be about 2.5 kPa.

It turns out to be one of my most well-read articles; it is eighth on my all-time hit list, although it only went up last January. And it has attracted a some comments, mostly appreciative. But a recent poster has pointed out to me that reports of high pressure are not limited to Wikipedia, and that in fact he has noted several manufacturers who claim similar ultra-high (by my reckoning) pressures in their catalogues.

So what gives? I know how to calculate the pressure of a centrifugal blower, and I think I have some idea of the dimensions and rpm's involved. So what gives? Do they install ultra-high speed DC motors, like in a router? Or do they have multi-stage blower assemblies? It just seems way out of line. And I'm not sure quite what you'd actually do with 20 kPa of suction. It sounds just a little bit dangerous to be waving around your living room.

Anyone care to weigh in on this question?

1 comment:

Jerusalem Bullyproof said...

I've just measured it for new 2200W Samsung.

Regular 2 l soda bottle has neck diameter just slightly smaller than vacuum's pipe and equal to 3cm (Area=3*3*pi/4=7cm^2).

My cleaner lift 2.5kg (full soda bottle plus another 500g).

So P=2.5/7=0.36 kg/cm^2, or 36000 Pas.

As you could expect. this result doesn't change when I've removed filters.