Running a vaccum cleaner at low power

Single c, double u. "vacwm".

Reply to
Graham.
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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.

Reply to
Cursitor Doom

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.

Reply to
Cursitor Doom

If you are running it stalled (air stalled that is) then no cooling air will be passing through the motor.

Reply to
John

motor might overheat with low airflow, or stall?

Reply to
Andy Burns

wots that then?

Reply to
The Natural Philosopher

The stuff between your ears.

Reply to
Andy Bennet

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 ...

Reply to
Adrian Caspersz

A *partial vaccum* if you prefer. It's a seriously big deal to generate a pure vaccum!

Reply to
Cursitor Doom

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?

Reply to
Cursitor Doom

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 ...

Reply to
Adrian Caspersz

I think our legend of typographical excellence was referring to ?vaccum? as opposed to ?vacuum?. Pot, kettle, black situation. ;-)

Tim

Reply to
Tim+

Cursitor Doom explained :

No, there's loads of it up there /!\

Reply to
Harry Bloomfield, Esq.

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.

Reply to
Harry Bloomfield, Esq.

A sebo cylinder vac has variable speed. So does my elderly Morphy Richards Bulldog vac (like a Henry).

Reply to
Andrew

Definitely a situation situation.

Reply to
Tim Streater

Whoosh....

Reply to
The Natural Philosopher

but what is a 'vaccum'

It's not in the dictionary

Reply to
The Natural Philosopher

The staggering thing is you and I are the only people who noticed...

Reply to
The Natural Philosopher

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

Reply to
Fredxx

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