Water Supply Pump Design with very long piping

[Geee Concepts]

Hi,

Good day.

I'm currently designing a pumping system for potable water supply in a rural community. Water from the the spring at the bottom of the mountain will be pumped at the top. The area from the spring has an estimated total elevation of 120m, and 1500m pipe length (200m on a slope @ 120m elevation and 1300m horizontal) using a 1" HDPE pipe to be supplied to a 1.5 cu.m tank. Water to be supplied would be at a a rate of 2 cu.m at about 1.2 m/s velocity. Now based on calculations, I would need a 2 HP pump with a 240m .001 cu.m/s discharge. I know this is not possible since it would be almost impossible to find it in the market, and most probably the piping at the pump discharge would not be able to hold the discharge pressure. Can anyone enlighten me on this? This would be my first time designing such application.

Thanks.

 

[1503-44]

Your project sounds reasonable. 1.2m/s is not a high velocity. 2 HP is not a lot of power. 1500m is not so long. So far OK, but you do not tell us how high the outlet is.

What is the elevation at the outlet?
Is the slope going up to the outlet higher than the spring, or down to a lower outlet elevation?

Apparently you think you need 240m head? If true, you will need to buy pipe with a grade of PE 25 or higher.

Why do you think your project is not possible?

A black swan to a turkey is a white swan to the butcher.

 

[LittleInch]

If I take your elevation difference as 120m then you have a static head of 120m/12 bar

Maximum pressure you have left is 4 bar for 16 bar rated PE Pipe.

Your flowrate isn't clear. You say 1l/sec but that's 3.6m3/hr and you seem to say 2m3/hr??

Either way just use standard sheets to find out the right size to get your flow with max 4 bar or 40m head loss. A small increase in size makes a huge difference in head loss.

You should be able to find pumps to do your duty it really isn't that bad.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[pierreick]

Hi,
Prepare a data sheet with a sketch and submit it to vendors to get a proposal .
note : your water tank seems small , your pump will start and stop quite often !
my view
Pierre

 

[MJCronin]

I agree with Pierre !!! The tank seems way too small and will wear out your pump too quickly ...

You should work from the tank backward to design the system.

First establish a flowrate, then size the size the tank so that pump will be running about half the time at peak demand. You goal here is that it should start no more often than three or four times per hour.

How do you propose to turn the pump on and off ? .... By level ?... By pressure or some other means ?

A sketch here and details of your proposed pump would help greatly ..

Tell us more and ....Good Luck !

MJCronin
Sr. Process Engineer

 

[Rputvin]

1.5 m3 tank (396 gallons) with a flowrate of 2m3/hour will take 45 minutes to fill. I don't see an issue with the size of the tank.

I think the only issue is the size of your pipe. At 1" over 1500m you're looking at around 8.5bar in pressure loss for your 2m3/hr flowrate. Add in the height you need to overcome and your discharge pressure is too high, as LittleInch noted.

Go up to 1.5" for your main pipe and your pressure requirement for the pipe drops to around 1.25bar and velocity is 0.5m/s for 2m3/hr, allowing your pump to operate at about 135m (13.2bar) of discharge head instead of over 200m.