Puddle pump. Help!

[penfold]

It either has priming apparatus(auxiliary pump and timer etc) or it has a sump and internal recirculation to retain enough water to create a seal and thus suction. Gilkes do a nice range of the latter.

 

[normspanners]

It either has priming apparatus(auxiliary pump and timer etc) or it has a sump and internal recirculation to retain enough water to create a seal and thus suction. Gilkes do a nice range of the latter.

irrespective of whether it is self priming or vacuum / compressor primed a centrifugal pump does not like any significant air being drawn into it,air entrainment causes erosion of parts as explained, this application (now resolved) is not a centrifugal pump job and should be done with a positive displacement pump and because of contamination with solids a diaphragm pump would have been the best way IMO

Air entrainment and pump cavitation have similar symptoms. In a centrifugal pump, they both have the ability to produce a rumbling, rattling noise, and cause
above base line vibration. If left unchecked, each can cause the impeller to become pitted and damaged. Though the effects of entrained air and pump cavitation are remarkably similar, their causes are quite different. Before troubleshooting the issue, understand which one you’re dealing with.
WHAT IS AIR ENTRAINMENT?
Air entrainment occurs when air or vapor bubbles are already in the fluid before reaching the pump. When the fluid reaches the eye of the impeller, they are subjected to higher pressures and implode on the surface of the impeller, just as they would where cavitation issues are present.

Air entrainment is common where:

• There is free falling discharge into a pit or tank near the pump’s suction line
• A leaky suction line
• Pump whose minimum submergence is not being met
• The product has air pockets by nature (paper stock, fermenting liquids, or foaming agents)

It is also hard to understand that it sometimes requires more power to pump a liquid with less head ie flat pumping, than with more head, if the pump requires a minimum head pressure you have to throttle down the outfall ie increase the pressure in the volute to reduce the power required. It is a little counter intuitive.

 

[knighty]

all of the 'self priming' centrifugal pumps I've seen have a venture inside and a small area for water... some of the water is allowed to re-circulate

so as the water is circulated, air is sucke in via the ventuire and expelled out of the liquid exit


you can normally recognise that type of pump just by looking at it, the impeller housing is pretty big/long


EDIT: like this

 

[Pete.]

PUDDLE pumps norm. That link you've copied from talks about permanent installations. Puddle pumps always suck up air, coz they are standing in a puddle.

 

[normspanners]

but a puddle pump ie centrifugal and a centrifugal will not pump air,and would not have removed all the water that the Op was asking and if left running for days would be damaged, he was also asking about fill a container so the pump knighty shows is not designed to drain to less than maybe 10/20 mm ( if lucky) but would also fill with grit and block and be damaged whereas a diaphragm pump would not be damaged and happily copes with air, and will actively pump air, and some water.
The place I do work for, that rent pumps out theirs are not permanent installations they are mostly mobile units and one of the main killers of centrifugal pumps is air ingress.

 

[Screwdriver]

Well it was the most horrible job for all sorts of reasons. I wanted to run everything 110v so I wasn't standing in a puddle with the risk of electrocution but the pump I bought some time ago, never arrived. On a whim I bought a second item with it and as soon as the seller started making excuses why he couldn't send it, I knew he was looking for a way out. Especially when the first thing he tells me is how expensive these things are new. The clincher is he now tells me I was being "greedy" (!) kind of a dumb thing to say to someone who just bought and paid for an item they were selling but a rather obvious admission they always intended to renege on the deal.

The knock on has been a costly one. I was going to sell those 110v site lights, the transformer and pump as a system but the basement needed to be pumped out before a gang of workmen shore up that clay wall tomorrow. Now I have drained it, it's going to be tricky to convince the client he needs 110v down there. Double whammy because I won't be there at the time and they'll be hoovering up some of the materials I put aside - although in fairness, I already have a lifetime supply of rebar!

It's about 50mm of water over 100sqm so circa 5,000 litres of filthy swamp water, complete with a zillion mosquito larvae. It was a little bit warmer yesterday so as soon as I disturbed the water, dozens of them woke up and started pestering. You can see the tin of Raid in a later shot...

I made up a sump and ramp so I could brush water into it at a high enough level.

It worked but I didn't need it. I had to buy another pump and it actually would lift water from 5 - 10 mm so long as you could prime it. I had to make up a relatively solid hose from odd bits of tube and a long spiral bound pipe but it was tricky to prime. I would arrange a couple of lengths of wood in a V shape and brush water into the dam until the pump picked up a head. Once there's a head of water in the pipe, it will pretty much suck up anything because it sort of clamps itself to the bottom like a limpet and the inlets were about 5mm high.

If the inlet becomes exposed to air and the head of water in the pipe falls, it obviously falls into the pump and back fills the leak. Upshot is I could move it to areas of slightly deeper water as they were revealed and literally brush a mound of water over it. There is a fair bit more water and dirt to remove (I'm not dealing with the dirt!) but there is so little water, it should be safe to sweep it out into the foundations, especially since there will soon be a structure supporting the clay wall.

Looking at the way the pumped water has carved a gouge into the garden, it was the right decision not to sweep it under the house. Going back down there later to tidy up and maybe get a wider shot of the site.