Single c, double u. "vacwm".
Single c, double u. "vacwm".
Gentlemen,
I need a bit of vaccum for a one-off experiment so it's not worth ordering a bespoke vaccum pump for. I have an upright vaccum cleaner that puts out (according to the back panel) 1800W at 220V and 2000W at
240V. I get just the perfect amount of mild suction I need when I hook it up to a variac and set it to 80V. I will need to leave this running for about 40 minutes at this lower power. I don't think there's any danger to the cleaner in doing this but thought it sensible to run the idea past the Panel just in case I've overlooked anything.Thanks.
Oh - I forgot to mention that the airflow through the system will be almost totally blocked, so the same effect as sticking your thumb over the end of the hose as it were.
If you are running it stalled (air stalled that is) then no cooling air will be passing through the motor.
motor might overheat with low airflow, or stall?
wots that then?
The stuff between your ears.
If that 80V is with the airflow restricted, I make that about 220W. Say
200W as pure heat.12v fan from a PC power supply would see most of that off.
What temperature would a x Kg lump of motor steel get to above ambient,over 40 minutes, if 220 Joules per second of energy is passed in, and would it burn off the insulation or other scary stuff?
I can't do school physics anymore ...
A *partial vaccum* if you prefer. It's a seriously big deal to generate a pure vaccum!
A valiant attempt, Adrian. OK, so let's say I up the voltage to (plucking a figure out of my arse here) 125V and 'bleed' a certain amount of air through the system, whilst monitoring the motor case temp with a thermistor?
Nah, I'm not really in the "Tune the system for minimum smoke" game.
I do my DIY by the habit of real overkill. No real calculations, but just loads of planks of wood deployed where just one would admirably support a floating seed from a dandelion .
Bodging with conscience ...
I think our legend of typographical excellence was referring to ?vaccum? as opposed to ?vacuum?. Pot, kettle, black situation. ;-)
Tim
Cursitor Doom explained :
No, there's loads of it up there /!\
Cursitor Doom explained :
Almost no airflow = rapid over heating of the motor.
You need a separate motor with vacuum pump, even then it will need some extra cooling airflow - not dependent on the motor speed.
A sebo cylinder vac has variable speed. So does my elderly Morphy Richards Bulldog vac (like a Henry).
Definitely a situation situation.
Whoosh....
but what is a 'vaccum'
It's not in the dictionary
The staggering thing is you and I are the only people who noticed...
I'd wager air flow is proportional to voltage but power loss is a square function.
Half voltage = half flow = 1/4 power loss.
I would be surprised if the exhaust air was hotter at reduced voltage.
BICBW
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