In message , Hugo Nebula
writes
Reading car forums, the overwhelming opinion is that a pressure washer
is needed to wash one's car properly. So I went and bought a cheap
Halfords one, complete with snow foam attachment. The results were
disappointing to say the least.

I know it's not a mega powerful one, but I was amazed at how low the
pressure was out of the nozzle. I was certain my hose gave a more
powerful flow, so I did an experiment and timed how long it took to
fill a bucket, and therefore what the flow rate is from my tap. It
amounts to 1,000 litres per hour, nearly three times the flow rate of
the PW. Some of the best pressure washers only appear to give half of
that.

Am I missing something here? Is pressure a function of the flow rate,
and if so, what's the point of a pressure washer if it gives less than
mains pressure?


They, as the name suggests, provide extra pressure and not flow rate, so
I would expect an open hose to provide a higher flow rate, otherwise
they would be sucking water out of your mains.

I use a middle of the road Karcher and it is marvellous, fetches paving
slabs and concrete back to a nice crisp finish and clears most of the
dirt off the car. If you have it on a pencil jet and it cuts the rubber
trim around the windows then it is OK. A problem I had when I first
used mine years ago. Quite good at taking paint off painted bumpers too
if there are any stone chips.
--
Bill