Indeed. That's why I find it so intuitively difficult to understand how it manages to achieve that when the outlet is only a couple of inches away from a 1" diameter hole into a 'low pressure' environment!
Kind Regards, John
How do submersible pumps work?
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Kind Regards, John
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Quite - and that is obviously what I was hoping to find, but didn't! Even before I opened it up I was pretty sure that there was no such problem, because I could see and rotate the impeller through the outlet, and could see that both inlet and outlets were totally clean.
Kind Regards, John
I once had a float switch that got crushed by a sludge gulper, it was simply 3 round cavities, the centre had 2 brass contacts at one end and a brass 'marble' sized ball which bridged between them. I always thought it was very crude but never gave a thought to alternatives. The level switches I've installed in tanks /sumps etc are usually a vertical tube containing a reed relay and a float around the tube which contains a magnet.
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Yes installed a number of them. Usually restricted to 8Vac for some reason. and the hardened stainless steel laquered rods which have to be cut with an anglegrinder.
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8Vac for safety in a very wet environment. We used to call them I think 'no floats'. One long tube for the common, a shorter one to stop the pump, the shortest for start - assuming pumping out, rather than in. Tube was galved steel gas pipe I think, suspended from like a bracketed top hat. A very simple system, yet so reliable and effective. Set and forget.
I spent a few years putting in and commissioning control systems, for what were sometimes major pumping schemes, motors so big they would fill a small room. Weir, Sulzer and Hawthorn Davey, before Sulzer swallowed them. Great fun to play with
I suspect that SUNRAY was asking "why as low as 8V?". A more 'standard' ELV voltage (like 12V) would be essentially just as safe.
Kind Regards, John
A long time ago, so I accepted his 8V, but I half remember them being 24V.
The impeller vanes will be very close to the plate containing the inlet hole, probably within 1mm.
If you can imagine, for a moment, that there is no gap and the impeller vanes are in perfect contact with the plate. In fact there is sometimes an additional plate added to the impeller.
As the impeller spins any water within the vanes is thrown outwards by centrifugal force and if there is somewhere for it to go - it will. The outlet in its crudest form is a hole in the side of the impeller void. Some air fans are built this way and the impeller may simply be against a division between 2 sections of air duct.
The outlet is usually angled and frequently has a scoop fashioned to reduce drag on the water flow, the curve on the vanes is more for directing the water towards the outlet than for sucking on the inlet.
If that were the case, then I'd find it much easier to understand. However, the impeller vanes are actually about 50 mm above the plate containing the 'input hole' - in fact, close to the top of the output port
Kind Regards, John
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.... something like ....
Kind Regards, John
Kind Regards, John
... and 'the vanes' of the impeller are amazingly small for something which produces such an enormous and 'powerful' gush of water ...
Kind Regards, John
Kind Regards, John
The versions I've encountered ran on 24Vac [pretty much the standard in control panels AFAIC] but the level relay contains a 24 to 8V transformer.
One of the problems with higher voltages [higher currents] is the gassing, [one of the easy ways to collect oxygen and hydrogen is to pass a dc current through water and harvest the bubbles].
Historically it could be something to do with it but the more recent versions contain electronics which reduces the current considerably.
The systems I'm familiar with consist of 3 laquered stainless steel rods, typically: longest = common, middle = stop pumping, top = start pumping for emptying. Or middle = order stock, top = stop filling etc.
It's a bit of a surprise the gap is that big, however the principle is still there. the impeller will still set up the water flow and I dare say a vortex to suck more in.
The bubbles will still be there but will contain O2 & H at both electrodes.
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