Pressure washers - useless, or less than useless?

[The Natural Philosopher]

flow rate is not pressure.

yes.

Is pressure a function of the flow rate,

No.

since it isn't so, think again.

[The Natural Philosopher]

[The Natural Philosopher]

That's why you vary the distance to the target and the nozzle dimensions.

They are not sandblasters.

[The Natural Philosopher]

add in getting winter lichen off the garden furniture..not bad at house paintwork and the windows, too.

[The Natural Philosopher]

Not a myth, because I have done it: If the paint is already loose they will take it off, but they wont take paint off a car at the sort of pressures and distances you normally use a toy one at.

A high pressure industrial jet jet will cut through steel plate...its all a question of muscle.

[John Rumm]

Have a look at the FAQ. The way to compare them is with the pressure

*and* flowrate - its the product of the two that does the work...

You would have a hard job stopping most cold mains taps with your thumb!

[Martin Brown]

Indeed, but it isn't a tool I would like to use on good car paintwork.

That depends how much sand and grit there is stuck on the car already. Mine picks up a lot of salt and mud (and this time of year muck) from local roads. Using a pressure washer would grind it into the paintwork.

[The Medway Handyman]

[Andy Burns]

I'm amazed you don't get an "exit wound" that's significantly wider

[Davey]

Interesting thought, that: If so, then any other tap open in the house would become a suction point instead of a water supply!

We lived in a place in the US once where the water main ran down the middle of the street, and each opposing pair of houses were supplied from one 'T' on the top of that main. Cold taps were supplied directly off the main, via a pressure regulator. The house opposite us had automatic sprinklers, and the folks who came every autumn to bleed it out never got the hang of where to attach their air compressor. For a day or so afterwards, we had explosive cold taps whenever we turned them on, until the air pocket had bled out.

[grimly4]

That's why I use the fan setting first, to wash off the grit and loose bits.