Fuse Rating on a Motor

[Brian Logan]

I think everyone is surprised when they first hear this, as its
counter intuitive. However if you look at the water path in the pump
when the in- or outlet is completely blocked, you'll notice a lot less
work is being done. All that happens is the water spins round in the
pump chamber freely with the impellor, with very little resistance to
its spinning.

The same happens with a cylinder vac: block the inlet and the motor
speeds up, not slows down. Cylinder vacs use a similar impellor type
to water pumps, ie centrifugal rather than traditional fan.

That makes sense. I see what you mean.

Dont think I've seen many pumps explode I know its possible, but
not really a significant issue unlses you get into really large
equipment. Any description that hints that a competing product might
not be upto the same spec tends to attract buyers, so there are a lot
of non-issues eagerly described by sellers.

A pump bursting into flames would also indicate a substandard pump.
And be somewhat difficult to achieve underwater of course. I'm so
cynical.

No, I meant flameproof/explosion proof from the point of view that the motor
won't cause an explosion in a potentially flammable atmosphere.