Pumping into the distribution lines

[brice14]

I'm building a system for about 10 homes. I would like to pump into the distribution system to avoid running/maintaining two tubes to the reservoir. I would like to turn on/off the pump with a standard pressure switch and a nearby pneumatic tank to avoid running wires to the reservoir.

At the reservoir, I am trying to figure out the best design to shut off the water when the tank is full but with only one feeder tube. If it makes a difference, pump flow will be less than 1 liter/sec. and lift between the pump and reservoir is 60 meters (84 PSI).

Two questions:

1. Is the pump turning on and off going to spike the pressure to a home nearby (10 meters higher and 75 meters away running in a 1" tube). I'd think not with a pneumatic tank in line, but one never knows.

2. My plan to turn off the water at the top is to have the one distribution tube branch at the tank. One branch will go against a one way valve at the bottom of the reservoir not allowing water to flow into the reservoir from the bottom, and the second branch will go to the top and be closed by a float valve when the tank is full. Is this a good design practice? I just sort of made it up because I can't find any good reference on how to design something like this without electric circuits.

 

[bimr]

Suggest you post a sketch.

 

[coloeng]

If this system is for only 10 homes, why not just use a pneumatic tank that is sized sufficiently and forget about the elevated tank? The pump would pump to a certain pressure and then shut off, once the pneumatic tank's pressure drops to a certain pressure the pump would turn back on to refill the tank and again increase the pressure.

 

[brice14]

The problem with using the pneumatic tank for 10 homes is that this is happening in Costa Rica and the electric goes down about once a day for one reason or another. This would cause water outage whenever there is electric outage. But, you sort of answered my question #1 because if you think it would work without the upper reservoir, then definitely there is no surge problem. I'm drawing something right now that will describe the upper system. Back shortly.

 

[cvg]

use the upper reservoir only for power outage emergency and rely on the hydrotank to provide supply at constant pressure. If the hydrotank is large enough it could provide adequate supply during a power outage. or perhaps it is cheaper to get a generator to power the pumps during power outage than to build a larger tank. 1 inch pipe seems a bit small.

 

[brice14]

Hi All,

First, thanks very much for your comments. I'm obviously new to this stuff and its great to get the feedback. I'm attaching two drawings of what is going on. The lower drawing is 100% standard (at least I've seen the layout many times before). But, it requires that the upper (and all distribution) be shut off in order for the pump to stop pumping. So, the "upper" drawing is what I'm mostly interested in. I've never seen it before, but it seems like it would have to work.

Thanks again.

 

[brice14]

This is the upper drawing...

 

[brice14]

Hi Cvg,

The flow rate of my source is small, so I need a reservoir somewhere to manage the peaks. Its already built at the top so it is not longer an option to move it.

Also, the 1" pipes go to homes from a 2" distribution line. Were you thinking 1" inadequate for a house or for the whole distribution system?

 

[cvg]

1 inch services and 2 inch distribution line may be adequate

 

[coloeng]

You could probably get it to work, but it may be easier and cheaper to just oversize your hydro-pneumatice tank and design it so that in the event of a power outage you would still have water, although at lower pressures.

The problem I can see with the two tank option is that you may end up with water quality problems in your upper tank. You need to make sure that you have sufficient water stored in the upper tank to allow for any power outage, yet at the same time you need to have enough turnover in the tank that the water doesn't become stagnant. You would need to design the system so that when the pneumatic tank was providing the water and the pumps was off, before the pump came back on some of the water from the upper tank drained out.

Good luck with your project and let us know how it goes.