On 01/04/2012 16:13, Hugo Nebula wrote:
[Default] On Sun, 01 Apr 2012 16:03:42 +0100, a certain chimpanzee,
, randomly hit the keyboard
and wrote:

There's certainly no need for them to shift vast volumes of water to be
effective. I think the point is that they generate (or should do) a very
high pressure by pumping water through a very small orifice. Certainly
my Karcher blasts out a very effective jet, but the actual flow rate is
way less than provided by a mains-fed tap.

So would a hose with a small nozzle not achieve the same effect?

There is a limit to the flow rate through a small nozzle unless you
apply a much larger pressure (ie pump) to the back side of it. People
make terrible mistakes with leaking high pressure hydraulics systems.

A small amount of water carrying a large amount of kinetic energy can do
a lot of damage. I would not use one on my car as I don't want to grit
blast the surface or strip the paint. YMMV Fine for use on dirty patios
though and stone doesn't suffer much from additional scratches.

--
Regards,
Martin Brown