Pump the mains in

happyhero

Hi This is just one of those theories, or odd conversations that you have about something, in fact I was talking to a friend the other day and we could not agree it would work.

As I said just a discussion, I am not actually going to do anything and I am not sure if you would be breaking any rules doing this, but in my area we are constantly told about how they are reducing the water pressure to cut down on the amount of water they are losing due to leaks, which is a bit annoying as it effects your shower, especially electric pumped ones sometimes to the point where they are pretty poor and also your boiler which I know my combination boiler never actually gets the water pressure it is designed to, yet they still continue to increase the costs for supplying you water.

It is a bit worrying sometimes, what pressure they will eventually drop the supply to, will it get to the point where some of my appliance cease to function?

Anyway the conversation we had was what if you fitted a pump to your incoming water supply after the stopcock, so that you could suck more through than is coming in with the current pressure,

Could it work?

Would they allow it as their intention is to reduce pressure to save on the leak problem but not necessarily to stop the amount they supply you, so would it break any rules (You could fit a non return as they often stipulate on many devices)?

Might be crazy idea, but may be this would be beneficial to your supplier, ie they could reduce pressure a bit further to reduce leaking and you could increase your own pressure to what you need (is it 3bar the ideal). Obviously this plan may fail if everyone increased their demand whilst the supplier reduced their supply, but an idea to work on.

Mutton_Geoff

It's against the regs because of the high risk of cavitation.

alanobrien

Yes it would work.
Cavitation is a risk if the pump is not vented or sealed correctly or if the volume of entrained gas (02) in the fluid is to high and comes out of solution.

In any case with a pump of such low pressure it would be easy enough to fit an automatic vent to avoid cavitation altogether.

happyhero

Cheers guys so would it be allowed if you could show that you had provided a vent to prevent cavitation, or would there still be a regulation against it?

Also I have read about this cavitation and am just curious, how could or would you end up with air in the fluid? Surely the water is there in the pipe under pressure waiting to come in. I suppose it could happen when they work on a local water main. I remember the odd occasion when local work has been done and you get a lot of coughing and spluttering occasionaly in these cases, but would the pump not cope with this brief air pocket?

alanobrien

happyhero wrote: »

Cheers guys so would it be allowed if you could show that you had provided a vent to prevent cavitation, or would there still be a regulation against it?

Also I have read about this cavitation and am just curious, how could or would you end up with air in the fluid? Surely the water is there in the pipe under pressure waiting to come in. I suppose it could happen when they work on a local water main. I remember the odd occasion when local work has been done and you get a lot of coughing and spluttering occasionaly in these cases, but would the pump not cope with this brief air pocket?

I suspect there are regs against it so that the volume pulled off doesn't exceed the volume being pumped by the water company. Water always contains dissolved oxygen, the percentage varies with temperature and pressure. Air can be drawn in to the pump via the main seal or any other seal it only takes a tiny gap. Yes the pump will cope with a small amount of cavitation but not to much. What normally happens is the entrained air gets drawn down to the outer diameter of the seal which is then starved of a fluid film and burns out.
Simple process happens a lot in industry.

ozskin

there are now specific pump systems designed to do just this job

happyhero

ozskin wrote: »

there are now specific pump systems designed to do just this job

have you got a link to one to see what they say about it?