Farmer's Well - GPM Output

I am not from SWUS so I need to know if the typical farmer's well has a pump on the other side of the pipe or does the water rises to the top by will power?

The flow can be estimated by measuring the height the water rises above the (level) top of the pipe.

Good afternoon, Hendrik, the sw US is very arid. It is not uncommon for the pump bowels to be at a depth of 1000 to 2000 ft. Of course the engine and gearhead are at grade.

That was the scenario I had in mind when I asked the question, but more realistically, the pump will be pumping from a surface pond into a ditch, which will carry the water away. I know I'm not being very technical, but that's about all I know about this project at this time.

Hi flyinghigh,

Your best bet is to get info on the pump itself. Manufacturers routinely give the kind of information you are seeking in the data/spec sheets. Typically, pump curves are shown. To learn about these, and how to interpret, see:

http://www.irrigationcraft.com/pump_curves.htm

Mike

I am a little confused here (not uncommon) Is the pump pumping from 1-2000 feet deep in the ground, a surface pond or both? It would make a huge difference on the output of the same motor I think.

Good morning pipewelder. Sorry for the confusion. Actually, its going to be pumping from a surface pond.

This is really going to depend on the capacity flow of the pump you are using and the water supply available (How fast the water replenishes). I just moved here from NM where I had a well also. If you use a pump that is rated to high, and the water is not able to replenish at a greater rate than what you are removing, you will end up running dry and burning up your pump (that is why a pump that uses sensor shut off works great).

However, cross-sectional area and length of pipe affect 'headloss', or essentially the resistance to flow of fluid through the pipe. The smaller the pipe diameter, the smaller the cross sectional area, and the greater the resistance to flow. Also, the longer the pipe, the greater the headloss and the greater the resistance to flow. So, the greater the headlosses of the pipe, the more you need to increase the pressure to get the same amount of flow. Water flow through a pipe is more dependant on the pressure difference from one end to the other than the diameter. For a given pressure, the flow can be determined by the diameter, but to determine the flow without knowing the pressure, is impossible.

Good morning MaintEng. Thx for your input. The water supply is unlimited. There will never be any cavitation. Assume the bowels of the pump will be 10 feet below the pump, which is placed at grade. Assume the length of 12" dia outlet pipe is also 10 feet, and feeds into a large ditch.

Maximum on a 12 inch pipe provides 8.5 ft per second of water or 510 ft per minute. 1 cubic ft = 7.48 US Liquid Gallons, so 510 ft/m x 7.48 = 3814.8 US Gallons per minute. This would be your maximum, but there are other issues that you would have to consider such as pressure. Your actual flow will depend on everything else and the capabilities of the pump you use, any 90's in your pipe..... Hope that helps a little anyways.

And the rate of replenishment is a function of a number of factors including the height of the water table and the soil makeup and borehole surface area in the area where water flows into the well.

Hello flyinghigh,

The pump that you should be using for the purpose described is used all over south Florida to irrigate citrus groves and sugar cane fields. They come in various sizes that are determined by the volume of water that is to be lifted from a pond or canal over a dyke or other retaining device and said water is deposited into the ditches for irrigating the crops. In every case the volume of water lifted is determined by the distance said water must be lifted.

These pumps are el shaped ( L ) with the short length being the discharge end. A propeller resembling one used for boating with the outer edges radiused to mach the circumference of the pipe is located near the lower end of the longer section of the pipe. A shaft connects this propeller to an electric motor located so as to be aligned in the center of the upper end of the longer leg of said pipe and connects to the propeller by a shaft. The motor is mounted on a bracket on the upper end of the apparatus and does not get wet, or impede the flow of water. As can be expected huge quantities of water are moved in a shorter period of time economically.

Google up High volume low pressure Irrigation pumps, and you will find what you are looking for and there are tables that can estimate the volume of water per hr. based on the head of lift you need.

TMF

Good morning Toomuchfun. Thx for your note. Initial investigation shows a 25hp, 3 phase, 12"in, 10"out, 40' head, will give ~3000gpm.