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Re: Mist Maker Question



William Beaty wrote:
On Tue, 16 May 2000, Tony Wayne wrote:

*** Background ***
Here a brain stumper. Florists and nurseries are now selling this little
device called a mist maker.

Ah, "ultrasonic nebulizers". I love those things.

I used to use them for spraying a chemical mist at hot glass (chemical
spray pyrolysis deposition of thin films). They provide a nice uniform
droplet size distribution and permit independent control over the
droplets and carrier gas. It was necessary however to build containment
chambers for the mixture with a thin piece of rigid plastic as a
membrane to pass the ultrasonic rays.

When people use polluted water, or if they let the humidifier sit around
for months so that bacteria grows in the water-well, the humidifier spews
water droplets which evaporate, leaving behind a cloud of infectious
particles. This is how Legionnaires disease was discovered: a humidifier
in a hotel's heating system caused an outbreak. Staphlococcus is pretty
common, so its a good idea to always use new tapwater when operating these
devices (and maybe put in a small bit of Clorox.)

I started using a cool mist humidifier around the apartment in Vancouver
and never had problems, but then we moved to Ontario for a few years
(grad studies) and stopped using it because of the fine white dust that
filled the room.


I once measured the frequency of an old humidifier. It ran at about
1.5MHz, if I recall.

Thats about what I recall too. We butchered a lot of these from
different makers and generally they were in the 1-2 MHz range.

As for how the beam generates the mist - all my reading said
"cavitation". In other words, I don't know.

()-()-()-()-()-()-()-()-()-()-()-()-()-()-()-()

Doug Craigen
http://www.dctech.com/physics/