🚀 go-pugleaf

Jon Green wrote on Fri, 24 Nov 2000

>fine nozzle would be
>ideal (you'd probably need a vent so that you don't overstress the
>cleaner's motor

Note: For air fans (and to a lesser degree centrifugal liquid pumps) the
motor is in fact under the most stress when it's pumping with the least
pressure difference and the maximum flowrate. The high pitch you hear
when vacuum cleaners are dead-ended is not because the motor is under
stress but because it's under no stress and is thus rotating at maximum
speed. The reduction in pitch when sucking without restriction is in
fact due to the motor slowing down because it is under load. It is
possible to burn out the motors of fans when blowing or sucking if (for
example) inlet and outlet pipes are removed which is the reverse of what
most people think.

> or generate too aggressive a suck -- oo-err!).  

Well, we wouldn't want that now would we?
Perish the thought.

-- 
Oz