Higgs Boson wrote:

about a new environmentally safer and more effective device for
performing some of the same functions currently handled by "brutal"
power washers.

What they're doing is a modification or extension of the concept of
ultrasonic cleaning as implimented in lab appliances like instrument
cleaners:

http://speedwaydelhi.com/images/(A-5...20Speedway.gif

These come in various sizes from about the size of a small toaster to
the size of a stove/oven.

What these guys are doing is directing ultrasonic energy through the
water stream to the object or surface being cleaned. What they don't
tell you is that you need a completely laminar or solid stream to flow
from the outlet to the surface. If that stream breaks up or separates
into smaller streams or becomes turbulent then the ultrasound can't be
conducted from the outlet nozzle to the surface being cleaned.

All the talk about hosing or washing down large surfaces from distances
of several feet is nonsense - you can't maintain a solid laminar "rod"
of water for that distance, and ultrasound is attenuated by travel over
large distances. And even if you could maintain a solid laminar rod of
water for a distance of several feet from a hand-held gun to a wall or
floor that you want to clean, you're only going to clean that small spot
where the water is hitting, and you're going to use a lot of water to
keep that stream flowing and intact.