Water Pump Question

Do you have any data on the gpm for each Rainbird^® sprinkler?

The power needed by any liquid mover is the pressure difference across it multiplied by the flowrate through it divided by the efficiency.

In this case, the first two pieces of information are not known to the forum, therefore it cannot size the pump nor make recommendations at this time.

Tornado has a very good point.

After determining the GPM requirement, and pressure needed for the 3 units, it's simply a matter of looking for a pump that can supply that much water at the required pressure and flow needed.

Be careful when looking at pump specs. Both flow and pressure must be considered.

If pump curves are available, look at them.

Also, remember gravity helps you. You will only have to lift the water 5' effectively since you have 20' of drop also. Then is a matter of considering friction losses over the 1400 foot run.

My guess is something in the 1 HP range would do.

Also if you had 220V service, use it.

TRy some of these, too: Sprinkler systems with pumps

Good luck.

Given your distance you may be better off using two pumps working together in a push pull configuration.

A submersible in the well pushing the 1400 feet and a slightly smaller rated jet pump boosting the pressure at the end.

Off the top of my head a 3/4 - 1 HP submersible with a 300+ deadhead rating and a 1/2 - 3/4 hp jet pump boosting the pressure for the sprinklers should give you all around good results.

I also wonder about the volume of water that your shallow well can produce at any given time. You might consider using a storage tank.

With this in mind, a windmill pump filling a raised storage tank could eliminate the need for any electric motor driven pump. There are just too many unknowns here to make a single recommendation. The only information I can tell you is that your piping alone will take just over 57 gallons of water to fill it.

We had a pretty good discussion on a similar topic here: http://cr4.globalspec.com/thread/56377

As someone else has noted, you need to know the specific rainbird. But as a point of reference if you had a total demand of 8 GPM (2.67 per sprinkler), the pressure loss in the pipe would be about 2 psi/100' (ignoring the down slope, since we don't know what it is) or 28 psi total. If the sprinklers need 30 psi, that gives a total discharge pressure of 58 psi. This is doable with a 1/2 HP submersible pump but might require a 3/4 HP jet pump. I'm using Grainger.com as a reference, again not a recommendation. If the pump will be only used for the sprinklers, you probably don't need a tank.

Again, the earlier post contains some good points to ponder.

Down slope is 20' over 1,400'.

Point is the water only has to be lifted 5' effectively. The slope is less than 1°, but, it's still there over the run of pipe.

I have friends who have a similar situation on their property. hey have a stock well which is basically severall 6' dia concrete culvert sections buried in the ground about 20 feet down.

The water table where they are will often times go a foot or better above the surrounding ground yet everything is dry as dust on the ground surface.

There garden is about 300 feet away and they have to pump water to it otherwise nothing grows.

Some years ago we tried pumping the stock well down to see what the refresh rate was and it took my 12,000 GPH pump 2 hours to drain it down and even then it was refreshing itself at close to 100 GPM once I hit the bottom!

Oops . Well 20 ft won't make but 10 psi difference. And, it's in his favor.

without getting into all the math just yet...I assume you're talking basic irrigation here. if so you'll probably want to have your pump fill a storage tank at the site you expect to irrigate. the amount of "feet of head" you'll need to operate your sprinklers will determine the size of your tank and the PSI you'll move your water. so get your sprinkler info and elevation information. then we can make suggestions

Since you want to supply water to 3 small rainbird (sprinklers ?), why don't you just go to the www.rainbird,com website and download their Manual on( sprinkler design)?...

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Let me try to clarify a bit. There are several manuals (and videos) available at this website, but the particular one that I meant can be a little difficult to locate.

So, to be more specific, try;

www.rainbird.com/documents/turf/IrrigationDesignManual.PDF

you seem to know what you what, have you taken your needs to a pump retailer?

Rainbird sprays have different nozzles that throw water out in different ways. Spray, large drops, low level, high and far etc. They do have a chart that tells you how far and how much water you get for a given pressure at the sprinkler. So...... step one, select the spray pattern you desire and then, step two, look for a pump that has the characteristics that you will need. The pump has a chart with it that shows its' pressure/flow characteristics. Step three, guess how many more sprinklers your wife will want you to add in the future, step four, measure your grade more accurately as you may end up with your sprinklers constantly running ( syphoning ) Step five, allow a bit extra for manufacturers fudge factor.

Jim